Subpart A General

Subpart B General Interpretations

Subpart C General Safety and Health Provisions

Subpart D Occupational Health and Environmental Controls

Subpart E Personal Protective and Life Saving Equipment

Subpart F Fire Protection and Prevention

Subpart G Signs, Signals, and Barricades

Subpart H Materials Handling, Storage, Use, and Disposal

Subpart I Tools - Hand and Power

Subpart J Welding and Cutting

Subpart K Electrical

Subpart L Scaffolds

Subpart M Fall Protection

Subpart N Helicopters, Hoists, Elevators, and Conveyors

Subpart O Motor Vehicles, Mechanized Equipment, and Marine Operations

Subpart P Excavations

Subpart Q Concrete and Masonry Construction

Subpart R Steel Erection

Subpart S Underground Construction, Caissons, Cofferdams, and Compressed Air

Subpart T Demolition

Subpart U Blasting and the Use of Explosives

Subpart V Electric Power Transmission and Distribution

Subpart W Rollover Protective Structures; Overhead Protection

Subpart X Stairways and Ladders

Subpart Y Commercial Diving Operations

Subpart Z Toxic and Hazardous Substances

Subpart AA Confined Spaces in Construction

Subpart BB [Reserved]

Subpart CC Cranes & Derricks in Construction

Authority: 40 U.S.C. 3704; 29 U.S.C. 653, 655, 657; Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), 3-2000 (65 FR 50017), 5-2002 (67 FR 65008), 5-2007 (72 FR 31160), 4-2010 (75 FR 55355), or 1-2012 (77 FR 3912); 29 CFR part 1911; and 5 U.S.C. 553, as applicable.

Section 1926.61 also issued under 49 U.S.C. 5101 et seq.

Section 1926.62 also issued under 42 U.S.C. 4853

Section 1926.65 also issued under 126 of Public Law 99-499, 100 Stat. 1613.

[55 FR 50687, Dec. 10, 1990; 57 FR 49272, Oct. 30, 1992; 58 FR 26627, May 4, 1993; 58 FR 34218, June 24, 1993; 58 FR 35310, June 30, 1993; 59 FR 6170, Feb. 9, 1994; 59 FR 17479, April 13, 1994; 59 FR 36695, July 19, 1994; 59 FR 43268, Aug. 22, 1994; 59 FR 65947, Dec. 22, 1994; 61 FR 9227, March 7, 1996; 61 FR 31427, June 20, 1996; 62 FR 1493, Jan. 10, 1997; 63 FR 1152, Jan. 8, 1998; 63 FR 33450, June 18, 1998; 70 FR 1143, Jan. 5, 2005; 71 FR 16674, April 3, 2006; 71 FR 50191, August 24, 2006; 73 FR 75588, Dec. 12, 2008; 76 FR 33611, June 8, 2011; 76 FR 80740, Dec. 27, 2011; 77 FR 17889, March 26, 2012; 78 FR 9315, Feb. 8, 2013; 81 FR 16875, March 25, 2016; 81 FR 60273, September 1, 2016; 82 FR 2750, Jan. 9, 2017]
The employer shall ensure the availability of medical personnel for advice and consultation on matters of occupational health.
Provisions shall be made prior to commencement of the project for prompt medical attention in case of serious injury.
In the absence of an infirmary, clinic, hospital, or physician, that is reasonably accessible in terms of time and distance to the worksite, which is available for the treatment of injured employees, a person who has a valid certificate in first-aid training from the U.S. Bureau of Mines, the American Red Cross, or equivalent training that can be verified by documentary evidence, shall be available at the worksite to render first aid.
First aid supplies shall be easily accessible when required.
The contents of the first aid kit shall be placed in a weatherproof container with individual sealed packages for each type of item, and shall be checked by the employer before being sent out on each job and at least weekly on each job to ensure that the expended items are replaced.
Proper equipment for prompt transportation of the injured person to a physician or hospital, or a communication system for contacting necessary ambulance service, shall be provided.
In areas where 911 is not available, the telephone numbers of the physicians, hospitals, or ambulances shall be conspicuously posted.
Where the eyes or body of any person may be exposed to injurious corrosive materials, suitable facilities for quick drenching or flushing of the eyes and body shall be provided within the work area for immediate emergency use.

[44 FR 8577, Feb. 9, 1979; 44 FR 20940, Apr. 6, 1979, as amended at 49 FR 18295, Apr. 30, 1984; 58 FR 35084, June 30, 1993; 61 FR 5507, Feb. 13, 1996; 63 FR 33450, June 18, 1998]
Appendix A to § 1926.50 -- First aid Kits (Non-Mandatory)

First aid supplies are required to be easily accessible under paragraph Sec. 1926.50(d)(1). An example of the minimal contents of a generic first aid kit is described in American National Standard (ANSI) Z308.1-1978 "Minimum Requirements for Industrial Unit-Type First-aid Kits". The contents of the kit listed in the ANSI standard should be adequate for small work sites. When larger operations or multiple operations are being conducted at the same location, employers should determine the need for additional first aid kits at the worksite, additional types of first aid equipment and supplies and additional quantities and types of supplies and equipment in the first aid kits.

In a similar fashion, employers who have unique or changing first-aid needs in their workplace may need to enhance their first-aid kits. The employer can use the OSHA 300 log, OSHA 301 log, or other reports to identify these unique problems. Consultation from the local fire/rescue department, appropriate medical professional, or local emergency room may be helpful to employers in these circumstances. By assessing the specific needs of their workplace, employers can ensure that reasonably anticipated supplies are available. Employers should assess the specific needs of their worksite periodically and augment the first aid kit appropriately.

If it is reasonably anticipated employees will be exposed to blood or other potentially infectious materials while using first-aid supplies, employers should provide personal protective equipment (PPE). Appropriate PPE includes gloves, gowns, face shields, masks and eye protection (see "Occupational Exposure to Blood borne Pathogens", 29 CFR 1910.1030(d)(3)) (56 FR 64175).

[63 FR 33450, June 18, 1998; 76 FR 80740, Dec. 27, 2011]
An adequate supply of potable water shall be provided in all places of employment.
Portable containers used to dispense drinking water shall be capable of being tightly closed, and equipped with a tap. Water shall not be dipped from containers.
Any container used to distribute drinking water shall be clearly marked as to the nature of its contents and not used for any other purpose.
The common drinking cup is prohibited.
Where single service cups (to be used but once) are supplied, both a sanitary container for the unused cups and a receptacle for disposing of the used cups shall be provided.
Potable water means water that meets the standards for drinking purposes of the State or local authority having jurisdiction, or water that meets the quality standards prescribed by the U.S. Environmental Protection Agency's National Primary Drinking Water Regulations (40 CFR part 141).
Outlets for nonpotable water, such as water for industrial or firefighting purposes only, shall be identified by signs meeting the requirements of Subpart G of this part, to indicate clearly that the water is unsafe and is not to be used for drinking, washing, or cooking purposes.
There shall be no cross-connection, open or potential, between a system furnishing potable water and a system furnishing nonpotable water.
Toilets shall be provided for employees according to the following table:

Table D-1
Number of
employees
Minimum number of facilities
20 or less 1
20 or more 1 toilet seat and 1 urinal per 40 workers.
200 or more 1 toilet seat and 1 urinal per 50 workers.
Under temporary field conditions, provisions shall be made to assure not less than one toilet facility is available.
Job sites, not provided with a sanitary sewer, shall be provided with one of the following toilet facilities unless prohibited by local codes:
Privies (where their use will not contaminate ground or surface water);
Recirculating toilets;
Combustion toilets.
Chemical toilets;
The requirements of this paragraph (c) for sanitation facilities shall not apply to mobile crews having transportation readily available to nearby toilet facilities.
All employees' food service facilities and operations shall meet the applicable laws, ordinances, and regulations of the jurisdictions in which they are located.
All employee food service facilities and operations shall be carried out in accordance with sound hygienic principles. In all places of employment where all or part of the food service is provided, the food dispensed shall be wholesome, free from spoilage, and shall be processed, prepared, handled, and stored in such a manner as to be protected against contamination.
When temporary sleeping quarters are provided, they shall be heated, ventilated, and lighted.
The employer shall provide adequate washing facilities for employees engaged in the application of paints, coating, herbicides, or insecticides, or in other operations where contaminants may be harmful to the employees. Such facilities shall be in near proximity to the worksite and shall be so equipped as to enable employees to remove such substances.
Washing facilities shall be maintained in a sanitary condition.
Lavatories shall be made available in all places of employment. The requirements of this subdivision do not apply to mobile crews or to normally unattended work locations if employees working at these locations have transportation readily available to nearby washing facilities which meet the other requirements of this paragraph.
Hand soap or similar cleansing agents shall be provided.
Individual hand towels or sections thereof, of cloth or paper, air blowers or clean individual sections of continuous cloth toweling, convenient to the lavatories, shall be provided.
Each lavatory shall be provided with hot and cold running water, or tepid running water.
Whenever showers are required by a particular standard, the showers shall be provided in accordance with paragraphs (f)(4)(ii) through (v) of this section.
Body soap or other appropriate cleansing agents convenient to the showers shall be provided as specified in paragraph (f)(3)(iii) of this section.
Showers shall be provided with hot and cold water feeding a common discharge line.
Employees who use showers shall be provided with individual clean towels.
One shower shall be provided for each 10 employees of each sex, or numerical fraction thereof, who are required to shower during the same shift.
No employee shall be allowed to consume food or beverages in a toilet room nor in any area exposed to a toxic material.
Every enclosed workplace shall be so constructed, equipped, and maintained, so far as reasonably practicable, as to prevent the entrance or harborage of rodents, insects, and other vermin. A continuing and effective extermination program shall be instituted where their presence is detected.
Whenever employees are required by a particular standard to wear protective clothing because of the possibility of contamination with toxic materials, change rooms equipped with storage facilities for street clothes and separate storage facilities for the protective clothing shall be provided.

[44 FR 8577, Feb. 9, 1979; 44 FR 20940, Apr. 6, 1979, as amended at 58 FR 35084; June 30, 1993; 76 FR 33611, June 8, 2011]
Protection against the effects of noise exposure shall be provided when the sound levels exceed those shown in Table D-2 of this section when measured on the A-scale of a standard sound level meter at slow response.
When employees are subjected to sound levels exceeding those listed in Table D-2 of this section, feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels within the levels of the table, personal protective equipment as required in Subpart E, shall be provided and used to reduce sound levels within the levels of the table.
If the variations in noise level involve maxima at intervals of 1 second or less, it is to be considered continuous.
In all cases where the sound levels exceed the values shown herein, a continuing, effective hearing conservation program shall be administered.

TABLE D-2 - PERMISSIBLE NOISE EXPOSURES
Duration per day,
hours
Sound level dBA
slow response
8 90
6 92
4 95
3 97
2 100
112 102
1 105
12 110
14 or less 115
When the daily noise exposure is composed of two or more periods of noise exposure of different levels, their combined effect should be considered, rather than the individual effect of each. Exposure to different levels for various periods of time shall be computed according to the formula set forth in paragraph (d)(2)(ii) of this section.
A sample computation showing an application of the formula in paragraph (d)(2)(ii) of this section is as follows. An employee is exposed at these levels for these periods:

110 db A 14 hour.
100 db A 12 hour.
90 db A 112 hours.

Fe = (14 divided by 12)+(12 divided by 2)+(112 divided by 8)
Fe = 0.500+0.25+0.188
Fe = 0.938


Since the value of Fe does not exceed unity, the exposure is within permissible limits.
Fe = (T1/L1) (T2/L2) · · · (Tn/Ln)
where:

Fe = The equivalent noise exposure factor.
T = The period of noise exposure at any essentially constant level.
L = The duration of the permissible noise exposure at the constant level (from Table D-2).


If the value of Fe exceeds unity (1) the exposure exceeds permissible levels.
Exposure to impulsive or impact noise should not exceed 140 dB peak sound pressure level.
In construction and related activities involving the use of sources of ionizing radiation, the pertinent provisions of the Nuclear Regulatory Commission Standards for Protection Against Radiation (10 CFR Part 20), relating to protection against occupational radiation exposure, shall apply.
Any activity which involves the use of radioactive materials or X-rays, whether or not under license from the Nuclear Regulatory Commission, shall be performed by competent persons specially trained in the proper and safe operation of such equipment. In the case of materials used under Commission license, only persons actually licensed, or competent persons under direction and supervision of the licensee, shall perform such work.
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]
[Reserved]

Note: The requirements applicable to construction work under paragraphs (c) through (r) of this section are identical to those set forth at paragraphs (a) through (p) of 1910.1096 of this chapter.

[44 FR 8577, Feb. 9, 1979; 44 FR 20940, Apr. 6, 1979, as amended at 58 FR 35084 & 35310; June 30, 1993; 61 FR 5507, Feb. 13, 1996; 61 FR 31427, June 20, 1996]
Only qualified and trained employees shall be assigned to install, adjust, and operate laser equipment.
Proof of qualification of the laser equipment operator shall be available and in possession of the operator at all times.
Employees, when working in areas in which a potential exposure to direct or reflected laser light greater than 0.005 watts (5 milliwatts) exists, shall be provided with antilaser eye protection devices as specified in Subpart E of this part.
Areas in which lasers are used shall be posted with standard laser warning placards.
Beam shutters or caps shall be utilized, or the laser turned off, when laser transmission is not actually required. When the laser is left unattended for a substantial period of time, such as during lunch hour, overnight, or at change of shifts, the laser shall be turned off.
Only mechanical or electronic means shall be used as a detector for guiding the internal alignment of the laser.
The laser beam shall not be directed at employees.
When it is raining or snowing, or when there is dust or fog in the air, the operation of laser systems shall be prohibited where practicable; in any event, employees shall be kept out of range of the area of source and target during such weather conditions.
Laser equipment shall bear a label to indicate maximum output.
Employees shall not be exposed to light intensities above:
Direct staring: 1 micro-watt per square centimeter;
Incidental observing: 1 milliwatt per square centimeter;
Diffused reflected light: 2 ½ watts per square centimeter.
Laser unit in operation should be set up above the heads of the employees, when possible.
Employees shall not be exposed to microwave power densities in excess of 10 milliwatts per square centimeter.
Exposure of employees to inhalation, ingestion, skin absorption, or contact with any material or substance at a concentration above those specified in the "Threshold Limit Values of Airborne Contaminants for 1970" of the American Conference of Governmental Industrial Hygienists, shall be avoided. See appendix A to this section.
To achieve compliance with paragraph (a) of this section, administrative or engineering controls must first be implemented whenever feasible. When such controls are not feasible to achieve full compliance, protective equipment or other protective measures shall be used to keep the exposure of employees to air contaminants within the limits prescribed in this section. Any equipment and technical measures used for this purpose must first be approved for each particular use by a competent industrial hygienist or other technically qualified person. Whenever respirators are used, their use shall comply with §1926.103.
Paragraphs (a) and (b) of this section do not apply to the exposure of employees to airborne asbestos, tremolite, anthophyllite, or actinolite dust. Whenever any employee is exposed to airborne asbestos, tremolite, anthophyllite, or actinolite dust, the requirements of §1910.1101 or §1926.58 of this title shall apply.
Paragraphs (a) and (b) of this section do not apply to the exposure of employees to formaldehyde. Whenever any employee is exposed to formaldehyde, the requirements of §1910.1048 of this title shall apply.

[39 FR 22801, June 24, 1974, as amended at 51 FR 37007, Oct. 17, 1986; 52 FR 46312, Dec. 4, 1987; 58 FR 35089; June 30, 1993]
Appendix A to § 1926.55—1970 American Conference of Governmental Industrial Hygienists' Threshold Limit Values of Airborne Contaminants

Threshold Limit Values of Airborne Contaminants for Construction
Substance CAS No.d ppma* mg/m3b Skin Designation
Abate; see Temephos
Acetaldehyde 75-07-0 200 360 -
Acetic acid 64-19-7 10 25 -
Acetic anhydride 108-24-7 5 20 -
Acetone 67-64-1 1000 2400 -
Acetonitrile 75-05-8 40 70 -
2-Acetylaminofluorine; see §1926.1114 53-96-3
Acetylene 74-86-2 E
Acetylene dichloride; see 1,2-Dichloroethylene
Acetylene tetrabromide 79-27-6 1 14 -
Acrolein 107-02-8 0.1 0.25 -
Acrylamide 79-06-1 - 0.3 X
Acrylonitrile; see §1926.1145 107-13-1
Aldrin 309-00-2 - 0.25 X
Allyl alcohol 107-18-6 2 5 X
Allyl chloride 107-05-1 1 3 -
Allyl glycidyl ether (AGE) 106-92-3 (C)10 (C)45 -
Allyl propyl disulfide 2179-59-1 2 12 -
alpha-Alumina 1344-28-1
Total dust - -
Respirable fraction - -
Alundum; see alpha-Alumina
4-Aminodiphenyl; see §1926.1111 92-67-1
2-Aminoethanol; see Ethanolamine
2-Aminopyridine 504-29-0 0.5 2 -
Ammonia 7664-41-7 50 35 -
Ammonium sulfamate 7773-06-0
Total dust - 15 -
Respirable fraction - 5 -
n-Amyl acetate 628-63-7 100 525 -
sec-Amyl acetate 626-38-0 125 650 -
Aniline and homologs 62-53-3 5 19 X
Anisidine (o-, p-isomers) 29191-52-4 - 0.5 X
Antimony and compounds (as Sb) 7440-36-0 - 0.5 -
ANTU (alpha Naphthylthiourea) 86-88-4 - 0.3 -
Argon 7440-37-1 E
Arsenic, inorganic compounds (as As); see §1926.1118 7440-38-2 - - -
Arsenic, organic compounds (as As) 7440-38-2 - 0.5 -
Arsine 7784-42-1 0.05 0.2 -
Asbestos; see 1926.58
Azinphos-methyl 86-50-0 - 0.2 X
Barium, soluble compounds (as Ba) 7440-39-3 - 0.5 -
Benzeneg; see §1926.1128 71-43-2
Benzidine; see §1926.1110 92-87-5
p-Benzoquinone; see Quinone
Benzo(a)pyrene; see Coal tar pitch volatiles
Benzoyl peroxide 94-36-0 - 5 -
Benzyl chloride 100-44-7 1 5 -
Beryllium and beryllium compounds (as Be); see 1926.1124 (q) 7440-41-7 - 0.002 -
Biphenyl; see Diphenyl
Bisphenol A; see Diglycidyl ether
Boron oxide 1303-86-2
Total dust - 15 -
Boron tribromide 10294-33-4 1 10 -
Boron trifluoride 7637-07-2 (C)1 (C)3 -
Bromine 7726-95-6 0.1 0.7 -
Bromine pentafluoride 7789-30-2 0.1 0.7 -
Bromoform 75-25-2 0.5 5 X
Butadiene (1,3-Butadiene); see 29 CFR 1910.1051; 29 CFR 1910.19(l) 106-99-0 STEL 1 ppm/5 ppm -
Butanethiol; see Butyl mercaptan
2-Butanone (Methyl ethyl ketone) 78-93-3 200 590 -
2-Butoxyethanol 111-76-2 50 240 X
n-Butyl-acetate 123-86-4 150 710 -
sec-Butyl acetate 105-46-4 200 950 -
tert-Butyl acetate 540-88-5 200 950 -
n-Butyl alcohol 71-36-3 100 300 -
sec-Butyl alcohol 78-92-2 150 450 -
tert-Butyl alcohol 75-65-0 100 300 -
Butylamine 109-73-9 (C)5 (C)15 X
tert-Butyl chromate (as CrO3); see 1926.1126n 1189-85-1
n-Butyl glycidyl ether (BGE) 2426-08-6 50 270 -
Butyl mercaptan 109-79-5 0.5 1.5 -
p-tert-Butyltoluene 98-51-1 10 60 -
Cadmium (as Cd); see 1926.1127 7440-43-9
Calcium carbonate 1317-65-3
Total dust - -
Respirable fraction - -
Calcium oxide 1305-78-8 - 5 -
Calcium sulfate 7778-18-9
Total dust - 15 -
Respirable fraction - 5 -
Camphor, synthetic 76-22-2 - 2 -
Carbaryl (Sevin) 63-25-2 - 5 -
Carbon black 1333-86-4 - 3.5 -
Carbon dioxide 124-38-9 5000 9000 -
Carbon disulfide 75-15-0 20 60 X
Carbon monoxide 630-08-0 50 55 -
Carbon tetrachloride 56-23-5 10 65 X
Cellulose 9004-34-6
Total dust - -
Respirable fraction - -
Chlordane 57-74-9 - 0.5 X
Chlorinated camphene 8001-35-2 - 0.5 X
Chlorinated diphenyl oxide 55720-99-5 - 0.5 -
Chlorine 7782-50-5 1 3 -
Chlorine dioxide 10049-04-4 0.1 0.3
Chlorine trifluoride 7790-91-2 (C)0.1 (C)0.4 -
Chloroacetaldehyde 107-20-0 (C)1 (C)3 -
a-Chloroacetophenone (Phenacyl chloride) 532-27-4 0.05 0.3 -
Chlorobenzene 108-90-7 75 350 -
o-Chlorobenzylidene malononitrile 2698-41-1 0.05 0.4 -
Chlorobromomethane 74-97-5 200 1050 -
2-Chloro-1,3-butadiene; see beta-Chloroprene
Chlorodiphenyl (42% Chlorine) (PCB) 53469-21-9 - 1 X
Chlorodiphenyl (54% Chlorine) (PCB) 11097-69-1 - 0.5 X
1-Chloro,2,3-epoxypropane; see Epichlorohydrin
2-Chloroethanol; see Ethylene chlorohydrin
Chloroethylene; see Vinyl chloride
Chloroform (Trichloromethane) 67-66-3 (C)50 (C)240 -
bis(Chloromethyl) ether; see §1926.1108 542-88-1
Chloromethyl methyl ether; see §1926.1106 107-30-2
1-Chloro-1-nitropropane 600-25-9 20 100 -
Chloropicrin 76-06-2 0.1 0.7 -
beta-Chloroprene 126-99-8 25 90 X
Chromium (II) compounds
(as Cr) 7440-47-3 - 0.5 -
Chromium (III) compounds
(as Cr) 7440-47-3 - 0.5 -
Chromium (VI) compounds; See 1926.1126o
Chromium metal and insol. salts (as Cr) 7440-47-3 - 1 -
Chrysene; see Coal tar pitch volatiles
Coal tar pitch volatiles (benzene soluble fraction), anthracene, BaP, phenanthrene, acridine, chrysene, pyrene 65996-93-2 - 0.2 -
Cobalt metal, dust, and fume (as Co) 7440-48-4 - 0.1 -
Coke oven emissions; see §1926.1129
Copper 7440-50-8
Fume (as Cu) - 0.1 -
Dusts and mists (as Cu) - 1 -
Corundum; see Emery
Cotton dust (raw) - 1
Crag herbicide (Sesone) 136-78-7
Total dust - -
Respirable fraction - -
Cresol, all isomers 1319-77-3 5 22 X
Crotonaldehyde 123-73-9; 2 6
4170-30-3
Cumene 98-82-8 50 245 X
Cyanides (as CN) Varies with Compound - 5 X
Cyanogen 460-19-5 10 - -
Cyclohexane 110-82-7 300 1050 -
Cyclohexanol 108-93-0 50 200 -
Cyclohexanone 108-94-1 50 200 -
Cyclohexene 110-83-8 300 1015 -
Cyclonite 121-82-4 - 1.5 X
Cyclopentadiene 542-92-7 75 200 -
DDT, see Dichlorodiphenyltrichloroethane
DDVP, see Dichlorvos
2,4-D (Dichlorophenoxyacetic acid) 94-75-7 - 10 -
Decaborane 17702-41-9 0.05 0.3 X
Demeton (Systox) 8065-48-3 - 0.1 X
Diacetone alcohol (4-Hydroxy-4-methyl-2-pentanone) 123-42-2 50 240 -
1,2-Diaminoethane; see Ethylenediamine
Diazomethane 334-88-3 0.2 0.4 -
Diborane 19287-45-7 0.1 0.1 -
1,2-Dibromo-3-chloropropane (DBCP); see §1926.1144 96-12-8 -
1,2-Dibromoethane; see Ethylene dibromide
Dibutyl phosphate 107-66-4 1 5 -
Dibutyl phthalate 84-74-2 - 5 -
Dichloroacetylene 7572-29-4 (C)0.1 (C)0.4 -
o-Dichlorobenzene 95-50-1 (C)50 (C)300 -
p-Dichlorobenzene 106-46-7 75 450 -
3,3′-Dichlorobenzidine; see §1926.1107 91-94-1
Dichlorodifluoromethane 75-71-8 1000 4950 -
1,3-Dichloro-5,5-dimethyl hydantoin 118-52-5 - 0.2 -
Dichlorodiphenyltrichloroethane (DDT) 50-29-3 - 1 X
1,1-Dichloroethane 75-34-3 100 400 -
1,2-Dichloroethane; see Ethylene dichloride
1,2-Dichloroethylene 540-59-0 200 790 -
Dichloroethyl ether 111-44-4 (C)15 (C)90 X
Dichloromethane; see Methylene chloride
Dichloromonofluoromethane 75-43-4 1000 4200 -
1,1-Dichloro-1-nitroethane 594-72-9 (C)10 (C)60 -
1,2-Dichloropropane; see Propylene dichloride
Dichlorotetrafluoroethane 76-14-2 1000 7000 -
Dichlorvos (DDVP) 62-73-7 - 1 X
Dieldrin 60-57-1 - 0.25 X
Diethylamine 109-89-7 25 75 -
2-Diethylaminoethanol 100-37-8 10 50 X
Diethylene triamine 111-40-0 (C)10 (C)42 X
Diethyl ether; see Ethyl ether
Difluorodibromomethane 75-61-6 100 860 -
Diglycidyl ether (DGE) 2238-07-5 (C)0.5 (C)2.8 -
Dihydroxybenzene; see Hydroquinone
Diisobutyl ketone 108-83-8 50 290 -
Diisopropylamine 108-18-9 5 20 X
4-Dimethylaminoazobenzene; see §1926.1115 60-11-7
Dimethoxymethane; see Methylal
Dimethyl acetamide 127-19-5 10 35 X
Dimethylamine 124-40-3 10 18 -
Dimethylaminobenzene; see Xylidine
Dimethylaniline (N,N-Dimethylaniline) 121-69-7 5 25 X
Dimethylbenzene; see Xylene
Dimethyl-1,2-dibromo- 2,2-dichloroethyl phosphate 300-76-5 - 3 -
Dimethylformamide 68-12-2 10 30 X
2,6-Dimethyl-4-heptanone; see Diisobutyl ketone
1,1-Dimethylhydrazine 57-14-7 0.5 1 X
Dimethylphthalate 131-11-3 - 5 -
Dimethyl sulfate 77-78-3 1 5 X
Dinitrobenzene (all isomers) 1 X
(ortho) 528-29-0
(meta) 99-65-0
(para) 100-25-4
Dinitro-o-cresol 534-52-1 - 0.2 X
Dinitrotoluene 25321-14-6 - 1.5 X
Dioxane (Diethylene dioxide) 123-91-1 100 360 X
Diphenyl (Biphenyl) 92-52-4 0.2 1 -
Diphenylamine 122-39-4 - 10 -
Diphenylmethane diisocyanate; see Methylene bisphenyl isocyanate
Dipropylene glycol methyl ether 34590-94-8 100 600 X
Di-sec octyl phthalate (Di-(2-ethylhexyl) phthalate) 117-81-7 - 5 -
Emery 12415-34-8
Total dust - -
Respirable fraction - -
Endosulfan 115-29-7 - 0.1 X
Endrin 72-20-8 - 0.1 X
Epichlorohydrin 106-89-8 5 19 X
EPN 2104-64-5 - 0.5 X
1,2-Epoxypropane; see Propylene oxide
2,3-Epoxy-1-propanol; see Glycidol
Ethane 74-84-0 E
Ethanethiol; see Ethyl mercaptan
Ethanolamine 141-43-5 3 6 -
2-Ethoxyethanol (Cellosolve) 110-80-5 200 740 X
2-Ethoxyethyl acetate (Cellosolve acetate) 111-15-9 100 540 X
Ethyl acetate 141-78-6 400 1400 -
Ethyl acrylate 140-88-5 25 100 X
Ethyl alcohol (Ethanol) 64-17-5 1000 1900 -
Ethylamine 75-04-7 10 18 -
Ethyl amyl ketone (5-Methyl-3-heptanone) 541-85-5 25 130 -
Ethyl benzene 100-41-4 100 435 -
Ethyl bromide 74-96-4 200 890 -
Ethyl butyl ketone (3-Heptanone) 106-35-4 50 230 -
Ethyl chloride 75-00-3 1000 2600 -
Ethyl ether 60-29-7 400 1200 -
Ethyl formate 109-94-4 100 300 -
Ethyl mercaptan 75-08-1 0.5 1 -
Ethyl silicate 78-10-4 100 850 -
Ethylene 74-85-1 E
Ethylene chlorohydrin 107-07-3 5 16 X
Ethylenediamine 107-15-3 10 25 -
Ethylene dibromide 106-93-4 (C)25 (C)190 X
Ethylene dichloride (1,2-Dichloroethane) 107-06-2 50 200 -
Ethylene glycol dinitrate 628-96-6 (C)0.2 (C)1 X
Ethylene glycol methyl acetate; see Methyl cellosolve acetate
Ethyleneimine; see §1926.1112 151-56-4
Ethylene oxide; see §1926.1147 75-21-8
Ethylidene chloride; see 1,1-Dichloroethane
N-Ethylmorpholine 100-74-3 20 94 X
Ferbam 14484-64-1
Total dust - 15 -
Ferrovanadium dust 12604-58-9 - 1 -
Fibrous Glass
Total dust -
Respirable fraction - -
Fluorides (as F) Varies with compound - 2.5 -
Fluorine 7782-41-4 0.1 0.2 -
Fluorotrichloromethane (Trichlorofluoromethane) 75-69-4 1000 5600 -
Formaldehyde; see §1926.1148 50-00-0
Formic acid 64-18-6 5 9 -
Furfural 98-01-1 5 20 X
Furfuryl alcohol 98-00-0 50 200 -
Gasoline 8006-61-9 A3 -
Glycerin (mist) 56-81-5
Total dust - -
Respirable fraction - -
Glycidol 556-52-5 50 150 -
Glycol monoethyl ether; see 2-Ethoxyethanol
Graphite, natural, respirable dust 7782-42-5 (2) (2) (2)
Graphite, synthetic
Total dust - -
Respirable fraction - -
Guthion; see Azinphos methyl
Gypsum 13397-24-5
Total dust - -
Respirable fraction - -
Hafnium 7440-58-6 - 0.5 -
Helium 7440-59-7 E
Heptachlor 76-44-8 - 0.5 X
Heptane (n-Heptane) 142-82-5 500 2000 -
Hexachloroethane 67-72-1 1 10 X
Hexachloronaphthalene 1335-87-1 - 0.2 X
n-Hexane 110-54-3 500 1800 -
2-Hexanone (Methyl n-butyl ketone) 591-78-6 100 410 -
Hexone (Methyl isobutyl ketone) 108-10-1 100 410 -
sec-Hexyl acetate 108-84-9 50 300 -
Hydrazine 302-01-2 1 1.3 X
Hydrogen 1333-74-0 E
Hydrogen bromide 10035-10-6 3 10 -
Hydrogen chloride 7647-01-0 (C)5 (C)7 -
Hydrogen cyanide 74-90-8 10 11 X
Hydrogen fluoride (as F) 7664-39-3 3 2 -
Hydrogen peroxide 7722-84-1 1 1.4 -
Hydrogen selenide (as Se) 7783-07-5 0.05 .02 -
Hydrogen sulfide 7783-06-4 10 15 -
Hydroquinone 123-31-9 - 2 -
Indene 95-13-6 10 45 -
Indium and compounds (as In) 7440-74-6 - 0.1 -
Iodine 7553-56-2 (C)0.1 (C)1 -
Iron oxide fume 1309-37-1 - 10 -
Iron salts (soluble) (as Fe) Varies with compound - 1 -
Isoamyl acetate 123-92-2 100 525 -
Isoamyl alcohol (primary and secondary) 123-51-3 100 360 -
Isobutyl acetate 110-19-0 150 700 -
Isobutyl alcohol 78-83-1 100 300 -
Isophorone 78-59-1 25 140 -
Isopropyl acetate 108-21-4 250 950 -
Isopropyl alcohol 67-63-0 400 980 -
Isopropylamine 75-31-0 5 12 -
Isopropyl ether 108-20-3 500 2100 -
Isopropyl glycidyl ether (IGE) 4016-14-2 50 240 -
Kaolin 1332-58-7
Total dust - -
Respirable fraction - -
Ketene 463-51-4 0.5 0.9 -
Lead, inorganic (as Pb); see 1926.62 7439-92-1
Limestone 1317-65-3
Total dust - -
Respirable fraction - -
Lindane 58-89-9 - 0.5 X
Lithium hydride 7580-67-8 - 0.025 -
L.P.G. (Liquefied petroleum gas) 68476-85-7 1000 1800
Magnesite 546-93-0
Total dust - -
Respirable fraction - -
Magnesium oxide fume 1309-48-4
Total particulate 15 - -
Malathion 121-75-5
Total dust - 15 X
Maleic anhydride 108-31-6 0.25
Manganese compounds (as Mn) 7439-96-5 - (C)5 -
Manganese fume (as Mn) 7439-96-5 - (C)5 -
Marble 1317-65-3
Total dust - -
Respirable fraction - -
Mercury (aryl and inorganic)(as Hg) 7439-97-6 0.1 X
Mercury (organo) alkyl compounds (as Hg) 7439-97-6 - 0.01 X
Mercury (vapor) (as Hg) 7439-97-6 - 0.1 X
Mesityl oxide 141-79-7 25 100 -
Methane 74-82-8 E
Methanethiol; see Methyl mercaptan
Methoxychlor 72-43-5
Total dust - 15 -
2-Methoxyethanol (Methyl cellosolve) 109-86-4 25 80 X
2-Methoxyethyl acetate (Methyl cellosolve acetate) 110-49-6 25 120 X
Methyl acetate 79-20-9 200 610 -
Methyl acetylene (Propyne) 74-99-7 1000 1650 -
Methyl acetylene-propadiene mixture (MAPP) 1000 1800 -
Methyl acrylate 96-33-3 10 35 X
Methylal (Dimethoxy-methane) 109-87-5 1000 3100 -
Methyl alcohol 67-56-1 200 260 -
Methylamine 74-89-5 10 12 -
Methyl amyl alcohol; see Methyl isobutyl carbinol
Methyl n-amyl ketone 110-43-0 100 465 -
Methyl bromide 74-83-9 (C)20 (C)80 X
Methyl butyl ketone; see 2-Hexanone
Methyl cellosolve; see 2-Methoxyethanol
Methyl cellosolve acetate; see 2-Methoxyethyl acetate
Methylene chloride; see §1910.1052
Methyl chloroform (1,1,1-Trichloroethane) 71-55-6 350 1900 -
Methylcyclohexane 108-87-2 500 2000 -
Methylcyclohexanol 25639-42-3 100 470 -
o-Methylcyclohexanone 583-60-8 100 460 X
Methylene chloride 75-09-2 500 1740 -
Methylenedianiline (MDA) 101-77-9
Methyl ethyl ketone (MEK); see 2-Butanone
Methyl formate 107-31-3 100 250 -
Methyl hydrazine (Monomethyl hydrazine) 60-34-4 (C)0.2 (C)0.35 X
Methyl iodide 74-88-4 5 28 X
Methyl isoamyl ketone 110-12-3 100 475 -
Methyl isobutyl carbinol 108-11-2 25 100 X
Methyl isobutyl ketone; see Hexone
Methyl isocyanate 624-83-9 0.02 0.05 X
Methyl mercaptan 74-93-1 0.5 1 -
Methyl methacrylate 80-62-6 100 410 -
Methyl propyl ketone; see 2-Pentanone
Methyl silicate 681-84-5 (C)5 (C)30 -
alpha-Methyl styrene 98-83-9 (C)100 (C)480 -
Methylene bisphenyl isocyanate (MDI) 101-68-8 (C)0.02 (C)0.2 -
Mica; see Silicates
Molybdenum (as Mo) 7439-98-7
Soluble compounds - 5 -
Insoluble compounds
Total dust - 15 -
Monomethyl aniline 100-61-8 2 9 X
Monomethyl hydrazine; see Methyl hydrazine
Morpholine 110-91-8 20 70 X
Naphtha (Coal tar) 8030-30-6 100 400 -
Naphthalene 91-20-3 10 50 -
alpha-Naphthylamine; see §1926.1104 134-32-7
beta-Naphthylamine; see §1926.1109 91-59-8 -
Neon 7440-01-9 E
Nickel carbonyl (as Ni) 13463-39-3 0.001 0.007 -
Nickel, metal and insoluble compounds (as Ni) 7440-02-0 - 1 -
Nickel, soluble compounds (as Ni) 7440-02-0 - 1 -
Nicotine 54-11-5 - 0.5 X
Nitric acid 7697-37-2 2 5 -
Nitric oxide 10102-43-9 25 30 -
p-Nitroaniline 100-01-6 1 6 X
Nitrobenzene 98-95-3 1 5 X
p-Nitrochlorobenzene 100-00-5 - 1 X
4-Nitrodiphenyl; see §1926.1103 92-93-3
Nitroethane 79-24-3 100 310 -
Nitrogen 7727-37-9 E
Nitrogen dioxide 10102-44-0 (C)5 (C)9 -
Nitrogen trifluoride 7783-54-2 10 29 -
Nitroglycerin 55-63-0 (C)0.2 (C)2 X
Nitromethane 75-52-5 100 250 -
1-Nitropropane 108-03-2 25 90 -
2-Nitropropane 79-46-9 25 90 -
N-Nitrosodimethylamine; see §1926.1116 62-79-9 -
Nitrotoluene (all isomers) 5 30 X
o-isomer 88-72-2;
m-isomer 99-08-1;
p-isomer 99-99-0
Nitrotrichloromethane; see Chloropicrin
Nitrous oxide 10024-97-2 E
Octachloronaphthalene 2234-13-1 - 0.1 X
Octane 111-65-9 400 1900 -
Oil mist, mineral 8012-95-1 - 5 -
Osmium tetroxide (as Os) 20816-12-0 - 0.002 -
Oxalic acid 144-62-7 - 1 -
Oxygen difluoride 7783-41-7 0.05 0.1 -
Ozone 10028-15-6 0.1 0.2 -
Paraquat, respirable dust 4685-14-7; - 0.5 X
1910-42-5;
2074-50-2
Parathion 56-38-2 - 0.1 X
Particulates not otherwise regulated
Total dust organic and inorganic - 15 -
PCB; see Chlorodiphenyl (42% and 54% chlorine)
Pentaborane 19624-22-7 0.005 0.01 -
Pentachloronaphthalene 1321-64-8 - 0.5 X
Pentachlorophenol 87-86-5 - 0.5 X
Pentaerythritol 115-77-5
Total dust - -
Respirable fraction - -
Pentane 109-66-0 500 1500 -
2-Pentanone (Methyl propyl ketone) 107-87-9 200 700 -
Perchloroethylene (Tetrachloroethylene) 127-18-4 100 670 -
Perchloromethyl mercaptan 594-42-3 0.1 0.8 -
Perchloryl fluoride 7616-94-6 3 13.5 -
Petroleum distillates (Naphtha)(Rubber Solvent) A3 -
Phenol 108-95-2 5 19 X
p-Phenylene diamine 106-50-3 - 0.1 X
Phenyl ether, vapor 101-84-8 1 7 -
Phenyl ether-biphenyl mixture, vapor 1 7 -
Phenylethylene; see Styrene
Phenyl glycidyl ether (PGE) 122-60-1 10 60 -
Phenylhydrazine 100-63-0 5 22 X
Phosdrin (Mevinphos) 7786-34-7 - 0.1 X
Phosgene (Carbonyl chloride) 75-44-5 0.1 0.4 -
Phosphine 7803-51-2 0.3 0.4 -
Phosphoric acid 7664-38-2 - 1 -
Phosphorus (yellow) 7723-14-0 - 0.1 -
Phosphorus pentachloride 10026-13-8 - 1 -
Phosphorus pentasulfide 1314-80-3 - 1 -
Phosphorus trichloride 7719-12-2 0.5 3 -
Phthalic anhydride 85-44-9 2 12 -
Picric acid 88-89-1 - 0.1 X
Pindone (2-Pivalyl-1,3-indandione) 83-26-1 - 0.1 -
Plaster of Paris 26499-65-0
Total dust - -
Respirable fraction - -
Platinum (as Pt) 7440-06-4
Metal - - -
Soluble salts - 0.002 -
Polytetrafluoroethylene decomposition products A2
Portland cement 65997-15-1
Total dust - 15 -
Respirable fraction 5 -
Propane 74-98-6 E
Propargyl alcohol 107-19-7 1 - X
beta-Propriolactone; see §1926.1113 57-57-8
n-Propyl acetate 109-60-4 200 840 -
n-Propyl alcohol 71-23-8 200 500 -
n-Propyl nitrate 627-13-4 25 110 -
Propylene dichloride 78-87-5 75 350 -
Propylene imine 75-55-8 2 5 X
Propylene oxide 75-56-9 100 240 -
Propyne; see Methyl acetylene
Pyrethrum 8003-34-7 - 5 -
Pyridine 110-86-1 5 15 -
Quinone 106-51-4 0.1 0.4 -
RDX; see Cyclonite
Rhodium (as Rh), metal fume and insoluble compounds 7440-16-6 - 0.1 -
Rhodium (as Rh), soluble compounds 7440-16-6 - 0.001 -
Ronnel 299-84-3 - 10 -
Rotenone 83-79-4 - 5 -
Rouge
Total dust - -
Respirable fraction - -
Selenium compounds (as Se) 7782-49-2 - 0.2 -
Selenium hexafluoride (as Se) 7783-79-1 0.05 0.4 -
Silica, amorphous, precipitated and gel 112926-00-8 (2) (2) (2)
Silica, amorphous, diatomaceous earth, containing less than 1% crystalline silica 61790-53-2 (2) (2) (2)
Silica, crystalline, respirable dust
Cristobalite; see 1926.1153 14464-46-1
Quartz; see 1926.11535 14808-60-7
Tripoli (as quartz); see 1926.11535 1317-95-9
Tridymite; see 1926.1153 15468-32-3
Silica, fused, respirable dust 60676-86-0 (2) (2) (2)
Silicates (less than 1% crystalline silica)
Mica (respirable dust) 12001-26-2 (2) (2) (2)
Soapstone, total dust (2) (2) (2)
Soapstone, respirable dust (2) (2) (2)
Talc (containing asbestos); use asbestos limit; see 1926.58
Talc (containing no asbestos), respirable dust 14807-96-6 (2) (2) (2)
Tremolite, asbestiform; see 1926.58
Silicon carbide 409-21-2
Total dust - -
Respirable fraction - -
Silver, metal and soluble compounds (as Ag) 7440-22-4 - 0.01 -
Soapstone; see Silicates
Sodium fluoroacetate 62-74-8 - 0.05 X
Sodium hydroxide 1310-73-2 - 2 -
Starch 9005-25-8
Total dust - -
Respirable fraction - -
Stibine 7803-52-3 0.1 0.5 -
Stoddard solvent 8052-41-3 200 1150 -
Strychnine 57-24-9 - 0.15 -
Styrene 100-42-5 (C)100 (C)420 -
Sucrose 57-50-1
Total dust - -
Respirable fraction - -
Sulfur dioxide 7446-09-5 5 13 -
Sulfur hexafluoride 2551-62-4 1000 6000 -
Sulfuric acid 7664-93-9 - 1 -
Sulfur monochloride 10025-67-9 1 6 -
Sulfur pentafluoride 5714-22-7 0.025 0.25 -
Sulfuryl fluoride 2699-79-8 5 20 -
Systox, see Demeton
2,4,5-T (2,4,5-trichlorophenoxyacetic acid) 93-76-5 - 10 -
Talc; see Silicates-
Tantalum, metal and oxide dust 7440-25-7 - 5 -
TEDP (Sulfotep) 3689-24-5 - 0.2 X
Teflon decomposition products A2
Tellurium and compounds (as Te) 13494-80-9 - 0.1 -
Tellurium hexafluoride (as Te) 7783-80-4 0.02 0.2 -
Temephos 3383-96-8
Total dust - -
Respirable fraction - -
TEPP (Tetraethyl pyrophosphate) 107-49-3 - 0.05 X
Terphenyls 26140-60-3 (C)1 (C)9 -
1,1,1,2-Tetrachloro-2,2-difluoroethane 76-11-9 500 4170 -
1,1,2,2-Tetrachloro-1,2-difluoroethane 76-12-0 500 4170 -
1,1,2,2-Tetrachloroethane 79-34-5 5 35 X
Tetrachloroethylene; see Perchloroethylene
Tetrachloromethane; see Carbon tetrachloride
Tetrachloronaphthalene 1335-88-2 - 2 X
Tetraethyl lead (as Pb) 78-00-2 - 0.1 X
Tetrahydrofuran 109-99-9 200 590 -
Tetramethyl lead, (as Pb) 75-74-1 - 0.15 X
Tetramethyl succinonitrile 3333-52-6 0.5 3 X
Tetranitromethane 509-14-8 1 8 -
Tetryl (2,4,6-Trinitrophenylmethylnitramine) 479-45-8 - 1.5 X
Thallium, soluble compounds (as Tl) 7440-28-0 - 0.1 X
Thiram 137-26-8 - 5 -
Tin, inorganic compounds (except oxides) (as Sn) 7440-31-5 - 2 -
Tin, organic compounds (as Sn) 7440-31-5 - 0.1 -
Tin oxide (as Sn) 21651-19-4 - - -
Total dust - -
Respirable fraction - -
Titanium dioxide 13463-67-7
Total dust - -
Toluene 108-88-3 200 750 -
Toluene-2,4-diisocyanate (TDI) 584-84-9 (C)0.02 (C)0.14 -
o-Toluidine 95-53-4 5 22 X
Toxaphene; see Chlorinated camphene
Tremolite; see Silicates
Tributyl phosphate 126-73-8 - 5 -
1,1,1-Trichloroethane; see Methyl chloroform
1,1,2-Trichloroethane 79-00-5 10 45 X
Trichloroethylene 79-01-6 100 535 -
Trichloromethane; see Chloroform
Trichloronaphthalene 1321-65-9 - 5 X
1,2,3-Trichloropropane 96-18-4 50 300 -
1,1,2-Trichloro-1,2,2-trifluoroethane 76-13-1 1000 7600 -
Triethylamine 121-44-8 25 100 -
Trifluorobromomethane 75-63-8 1000 6100 -
Trimethyl benzene 25551-13-7 25 120 -
2,4,6-Trinitrophenol; see Picric acid
2,4,6-Trinitrophenylmethylnitramine; see Tetryl
2,4,6-Trinitrotoluene (TNT) 118-96-7 - 1.5 X
Triorthocresyl phosphate 78-30-8 - 0.1 -
Triphenyl phosphate 115-86-6 - 3 -
Tungsten (as W) 7440-33-7
Insoluble compounds - 5 -
Soluble compounds - 1 -
Turpentine 8006-64-2 100 560 -
Uranium (as U) 7440-61-1
Soluble compounds - 0.2 -
Insoluble compounds - 0.2 -
Vanadium 1314-62-1
Respirable dust (as V2O5) - (C)0.5 -
Fume (as V2O5) - (C)0.1 -
Vegetable oil mist
Total dust - -
Respirable fraction - -
Vinyl benzene; see Styrene
Vinyl chloride; see §1926.1117 75-01-4
Vinyl cyanide; see Acrylonitrile
Vinyl toluene 25013-15-4 100 480 -
Warfarin 81-81-2 - 0.1 -
Xylenes (o-, m-, p-isomers) 1330-20-7 100 435 -
Xylidine 1300-73-8 5 25 X
Yttrium 7440-65-5 - 1 -
Zinc chloride fume 7646-85-7 - 1 -
Zinc oxide fume 1314-13-2 - 5 -
Zinc oxide 1314-13-2
Total dust - 15 -
Respirable fraction - 5 -
Zirconium compounds (as Zr) 7440-67-7 - 5


Mineral Dusts
Substance mppcf(j)
SILICA:
CrystallineQuartz. Threshold Limit calculated from the formula (p) 250(k)
________________
%SiO2 + 5
Cristobalite
Amorphous, including natural diatomaceous earth 20
SILICATES (less than 1% crystalline silica)
Mica 20
Portland cement 50
Soapstone 20
Talc (non-asbestiform) 20
Talc (fibrous), use asbestos limit --
Graphite (natural) 15
Inert or Nuisance Particulates:(m) 50 (or 15 mg/m3 whichever is the smaller) of total dust <1% SiO2
[Inert or Nuisance Dusts includes all mineral, inorganic, and organic dusts as indicated by examples in TLV's appendix D]
Conversion factors
mppcf × 35.3 = million particles per cubic meter = particles per c.c.


Footnotes

1 [Reserved]

2 See Mineral Dusts Table.

3 Use Asbestos Limit §1926.58.

4 See 1926.58.

5 See Mineral Dusts table for the exposure limit for any operations or sectors where the exposure limit in § 1926.1153 is stayed or is otherwise not in effect

* The PELs are 8-hour TWAs unless otherwise noted; a (C) designation denotes a ceiling limit.

** As determined from breathing-zone air samples.

a Parts of vapor or gas per million parts of contaminated air by volume at 25 °C and 760 torr.

b Milligrams of substance per cubic meter of air. When entry is in this column only, the value is exact; when listed with a ppm entry, it is approximate.

c [Reserved]

d The CAS number is for information only. Enforcement is based on the substance name. For an entry covering more than one metal compound, measured as the metal, the CAS number for the metal is given—not CAS numbers for the individual compounds.

e-f [Reserved]

g For sectors excluded from §1926.1128 the limit is 10 ppm TWA.

h-i [Reserved]

j Millions of particles per cubic foot of air, based on impinger samples counted by light-field techniques.

k The percentage of crystalline silica in the formula is the amount determined from airborne samples, except in those instances in which other methods have been shown to be applicable.

l [Reserved]

m Covers all organic and inorganic particulates not otherwise regulated. Same as Particulates Not Otherwise Regulated.

n If the exposure limit in §1926.1126 is stayed or is otherwise not in effect, the exposure limit is a ceiling of 0.1 mg/m3.

o If the exposure limit in §1926.1126 is stayed or is otherwise not in effect, the exposure limit is 0.1 mg/m3 (as CrO3) as an 8-hour TWA.

p This standard applies to any operations or sectors for which the respirable crystalline silica standard, 1926.1153, is stayed or otherwise is not in effect.

q This standard applies to any operations or sectors for which the beryllium standard, 1926.1124, is stayed or otherwise is not in effect.

The 1970 TLV uses letter designations instead of a numerical value as follows:

A1 [Reserved]

A2 Polytetrafluoroethylene decomposition products. Because these products decompose in part by hydrolysis in alkaline solution, they can be quantitatively determined in air as fluoride to provide an index of exposure. No TLV is recommended pending determination of the toxicity of the products, but air concentrations should be minimal.

A3 Gasoline and/or Petroleum Distillates. The composition of these materials varies greatly and thus a single TLV for all types of these materials is no longer applicable. The content of benzene, other aromatics and additives should be determined to arrive at the appropriate TLV.

E Simple asphyxiants. The limiting factor is the available oxygen which shall be at least 19.5% and be within the requirements addressing explosion in part 1926.

[39 FR 22801, June 24, 1974, as amended at 51 FR 37007, Oct. 17, 1986; 52 FR 46312, Dec 4, 1987; 58 FR 35089, June 30, 1993; 61 FR 9227, March 7, 1996; 61 FR 56746, Nov. 4, 1996; 62 FR 1493, Jan. 10, 1997; 71 FR 10381, Feb. 28, 2006; 81 FR 16875, March 25, 2016; 81 FR 60273-60274, September 1, 2016; 82 FR 2750-2751, Jan. 9, 2017]
Construction areas, ramps, runways, corridors, offices, shops, and storage areas shall be lighted to not less than the minimum illumination intensities listed in Table D-3 while any work is in progress:


TABLE D-3 - MINIMUM ILLUMINATION INTENSITIES IN FOOT-CANDLES

Foot-Candles Area of Operation
5 General construction area lighting.
3 General construction areas, concrete placement
excavation and waste areas, access ways, active
storage areas, loading platforms, refueling, and
field maintenance areas.
5 Indoors: warehouses, corridors, hallways, and
exitways.
5 Tunnels, shafts, and general underground work areas:
(Exception: minimum of 10 foot-candles is required
at tunnel and shaft heading during drilling,
mucking, and scaling. Bureau of Mines approved cap
lights shall be acceptable for use in the tunnel
heading)
10 General construction plant and shops (e.g., batch
plants, screening plants, mechanical and
electrical equipment rooms, carpenter shops,
rigging lofts and active store rooms, mess halls,
and indoor toilets and workrooms.)
30 First aid stations, infirmaries, and offices.
For areas or operations not covered above, refer to the American National Standard A11.1-1965, R1970, Practice for Industrial Lighting, for recommended values of illumination.
Whenever hazardous substances such as dusts, fumes, mists, vapors, or gases exist or are produced in the course of construction work, their concentrations shall not exceed the limits specified in 1926.55(a). When ventilation is used as an engineering control method, the system shall be installed and operated according to the requirements of this section.
Local exhaust ventilation when used as described in (a) shall be designed to prevent dispersion into the air of dusts, fumes, mists, vapors, and gases in concentrations causing harmful exposure. Such exhaust systems shall be so designed that dusts, fumes, mists, vapors, or gases are not drawn through the work area of employees.
Exhaust fans, jets, ducts, hoods, separators, and all necessary appurtenances, including refuse receptacles, shall be so designed, constructed, maintained and operated as to ensure the required protection by maintaining a volume and velocity of exhaust air sufficient to gather dusts, fumes, vapors, or gases from said equipment or process, and to convey them to suitable points of safe disposal, thereby preventing their dispersion in harmful quantities into the atmosphere where employees work.
The exhaust system shall be in operation continually during all operations which it is designed to serve. If the employee remains in the contaminated zone, the system shall continue to operate after the cessation of said operations, the length of time to depend upon the individual circumstances and effectiveness of the general ventilation system.
Since dust capable of causing disability is, according to the best medical opinion, of microscopic size, tending to remain for hours in suspension in still air, it is essential that the exhaust system be continued in operation for a time after the work process or equipment served by the same shall have ceased, in order to ensure the removal of the harmful elements to the required extent. For the same reason, employees wearing respiratory equipment should not remove same immediately until the atmosphere seems clear.
The air outlet from every dust separator, and the dusts, fumes, mists, vapors, or gases collected by an exhaust or ventilating system shall discharge to the outside atmosphere. Collecting systems which return air to work area may be used if concentrations which accumulate in the work area air do not result in harmful exposure to employees. Dust and refuse discharged from an exhaust system shall be disposed of in such a manner that it will not result in harmful exposure to employees.
A solid substance used in an abrasive blasting operation.
A complete enclosure which rotates on an axis, or which has an internal moving tread to tumble the parts, in order to expose various surfaces of the parts to the action of an automatic blast spray.
A complete enclosure in which blasting operations are performed and where the operator works inside of the room to operate the blasting nozzle and direct the flow of the abrasive material.
An air purifying respirator, commonly referred to as a dust or a fume respirator, which removes most of the dust or fume from the air passing through the device.
An enclosure where the operator stands outside and operates the blasting nozzle through an opening or openings in the enclosure.
Air of such purity that it will not cause harm or discomfort to an individual if it is inhaled for extended periods of time.
A device or combination of devices for separating dust from the air handled by an exhaust ventilation system.
A system for removing contaminated air from a space, comprising two or more of the following elements (A) enclosure or hood, (B) duct work, (C) dust collecting equipment, (D) exhauster, and (E) discharge stack.
Airborne dust in sizes capable of passing through the upper respiratory system to reach the lower lung passages.
An enclosure where the pieces to be cleaned are positioned on a rotating table and are passed automatically through a series of blast sprays.
The forcible application of an abrasive to a surface by pneumatic pressure, hydraulic pressure, or centrifugal force.
A respirator constructed so that it covers the wearer's head, neck, and shoulders to protect the wearer from rebounding abrasive.
Abrasives and the surface coatings on the materials blasted are shattered and pulverized during blasting operations and the dust formed will contain particles of respirable size. The composition and toxicity of the dust from these sources shall be considered in making an evaluation of the potential health hazards.
Organic abrasives which are combustible shall be used only in automatic systems. Where flammable or explosive dust mixtures may be present, the construction of the equipment, including the exhaust system and all electric wiring, shall conform to the requirements of American National Standard Installation of Blower and Exhaust Systems for Dust, Stock, and Vapor Removal or Conveying, Z33.1-1961 (NFPA 91-1961), and Subpart S of this part. The blast nozzle shall be bonded and grounded to prevent the build up of static charges. Where flammable or explosive dust mixtures may be present, the abrasive blasting enclosure, the ducts, and the dust collector shall be constructed with loose panels or explosion venting areas, located on sides away from any occupied area, to provide for pressure relief in case of explosion, following the principles set forth in the National Fire Protection Association Explosion venting Guide. NFPA 68-1954.
The concentration of respirable dust or fume in the breathing zone of the abrasive-blasting operator or any other worker shall be kept below the levels specified in 1926.55 or other pertinent sections of this part.
Blast-cleaning enclosures shall be exhaust ventilated in such a way that a continuous inward flow of air will be maintained at all openings in the enclosure during the blasting operation.
All air inlets and access openings shall be baffled or so arranged that by the combination of inward air flow and baffling the escape of abrasive or dust particles into an adjacent work area will be minimized and visible spurts of dust will not be observed.
The rate of exhaust shall be sufficient to provide prompt clearance of the dust-laden air within the enclosure after the cessation of blasting.
Before the enclosure is opened, the blast shall be turned off and the exhaust system shall be run for a sufficient period of time to remove the dusty air within the enclosure.
Safety glass protected by screening shall be used in observation windows, where hard deep-cutting abrasives are used.
Slit abrasive-resistant baffles shall be installed in multiple sets at all small access openings where dust might escape, and shall be inspected regularly and replaced when needed.
Doors shall be flanged and tight when closed.
Door on blast-cleaning rooms shall be operable from both inside and outside, except that where there is a small operator access door, the large work access door may be closed or opened from the outside only.
The construction, installation, inspection, and maintenance of exhaust systems shall conform to the principles and requirements set forth in American National Standard Fundamentals Governing the Design and Operation of Local Exhaust Systems, Z9.2-1960, and ANSI Z33.1-1961.
When dust leaks are noted, repairs shall be made as soon as possible.
The static pressure drop at the exhaust ducts leading from the equipment shall be checked when the installation is completed and periodically thereafter to assure continued satisfactory operation. Whenever an appreciable change in the pressure drop indicates a partial blockage, the system shall be cleaned and returned to normal operating condition.
The air exhausted from blast-cleaning equipment shall be discharged through dust collecting equipment. Dust collectors shall be set up so that the accumulated dust can be emptied and removed without contaminating other working areas.
In installation where the abrasive is recirculated, the exhaust ventilation system for the blasting enclosure shall not be relied upon for the removal of fines from the spent abrasive instead of an abrasive separator. An abrasive separator shall be provided for the purpose.
Employers must use only respirators approved by NIOSH under 42 CFR part 84 for protecting employees from dusts produced during abrasive-blasting operations.
Properly fitted particulate-filter respirators, commonly referred to as dust-filter respirators, may be used for short, intermittent, or occasional dust exposures such as cleanup, dumping of dust collectors, or unloading shipments of sand at a receiving point when it is not feasible to control the dust by enclosure, exhaust ventilation, or other means. The respirators used must be approved by NIOSH under 42 CFR part 84 for protection against the specific type of dust encountered.
A respiratory protection program as defined and described in 1926.103, shall be established wherever it is necessary to use respiratory protective equipment.
Operators shall be equipped with heavy canvas or leather gloves and aprons or equivalent protection to protect them from the impact of abrasives. Safety shoes shall be worn to protect against foot injury where heavy pieces of work are handled.
Safety shoes shall conform to the requirements of American National Standard for Men's Safety-Toe Footwear, Z41.1-1967.
Equipment for protection of the eyes and face shall be supplied to the operator when the respirator design does not provide such protection and to any other personnel working in the vicinity of abrasive blasting operations. This equipment shall conform to the requirements of 1926.102.
Abrasive-blasting respirators shall be worn by all abrasive-blasting operators:
When working inside of blast-cleaning rooms, or
When using silica sand in manual blasting operations where the nozzle and blast are not physically separated from the operator in an exhaust ventilated enclosure, or
Where concentrations of toxic dust dispersed by the abrasive blasting may exceed the limits set in 1926.55 or other pertinent sections of this part and the nozzle and blast are not physically separated from the operator in an exhaust-ventilated enclosure.
Air for abrasive-blasting respirators must be free of harmful quantities of dusts, mists, or noxious gases, and must meet the requirements for supplied-air quality and use specified in 29 CFR 1910.134(i).
Dust shall not be permitted to accumulate on the floor or on ledges outside of an abrasive-blasting enclosure, and dust spills shall be cleaned up promptly. Aisles and walkways shall be kept clear of steel shot or similar abrasive which may create a slipping hazard.
This paragraph applies to all operations where an abrasive is forcibly applied to a surface by pneumatic or hydraulic pressure, or by centrifugal force. It does not apply to steam blasting, or steam cleaning, or hydraulic cleaning methods where work is done without the aid of abrasives.
Organic-bonded wheels, the thickness of which is not more than one forty-eighth of their diameter for those up to, and including, 20 inches (50.8 cm) in diameter, and not more than one-sixtieth of their diameter for those larger than 20 inches (50.8 cm) in diameter, used for a multitude of operations variously known as cutting, cutting off, grooving, slotting, coping, and jointing, and the like. The wheels may be "solid" consisting of organic-bonded abrasive material throughout, "steel centered" consisting of a steel disc with a rim of organic-bonded material molded around the periphery, or of the "inserted tooth" type consisting of a steel disc with organic-bonded abrasive teeth or inserts mechanically secured around the periphery.
The part of an exhaust system piping that is connected directly to the hood or enclosure.
A movable fixture, upon which the part to be ground or polished is placed.
A pipe into which one or more branch pipes enter and which connects such branch pipes to the remainder of the exhaust system.
All power-driven rotatable discs faced with abrasive materials, artificial or natural, and used for grinding or polishing on the side of the assembled disc.
The loss in static pressure caused by air flowing into a duct or hood. It is usually expressed in inches of water gauge.
A system consisting of branch pipes connected to hoods or enclosures, one or more header pipes, an exhaust fan, means for separating solid contaminants from the air flowing in the system, and a discharge stack to outside.
All power-driven rotatable grinding or abrasive wheels, except disc wheels as defined in this standard, consisting of abrasive particles held together by artificial or natural bonds and used for peripheral grinding.
The partial or complete enclosure around the wheel or disc through which air enters an exhaust system during operation.
A grinding machine carrying two power-driven, rotatable, coaxial, horizontal spindles upon the inside ends of which are mounted abrasive disc wheels used for grinding two surfaces simultaneously.
A grinding machine carrying an abrasive disc wheel upon one or both ends of a power-driven, rotatable single horizontal spindle.
All power-driven rotatable wheels composed all or in part of textile fabrics, wood, felt, leather, paper, and may be coated with abrasives on the periphery of the wheel for purposes of polishing, buffing, and light grinding.
Any power-driven rotatable grinding, polishing, or buffing wheel mounted in such manner that it may be manually manipulated.
All power-driven rotatable wheels made from wire or bristles, and used for scratch cleaning and brushing purposes.
Any power-driven rotatable grinding, polishing, or buffing wheel mounted in such a manner that the wheel with its supporting framework can be manipulated over stationary objects.
The kinetic pressure in the direction of flow necessary to cause a fluid at rest to flow at a given velocity. It is usually expressed in inches of water gauge.
A grinding machine having a vertical, rotatable power-driven spindle carrying a horizontal abrasive disc wheel.
All power-driven, flexible, coated bands used for grinding, polishing, or buffing purposes.
Wherever dry grinding, dry polishing or buffing is performed, and employee exposure, without regard to the use of respirators, exceeds the permissible exposure limits prescribed in 1926.55 or other pertinent sections of this part, a local exhaust ventilation system shall be provided and used to maintain employee exposures within the prescribed limits.
Hoods connected to exhaust systems shall be used, and such hoods shall be designed, located, and placed so that the dust or dirt particles shall fall or be projected into the hoods in the direction of the air flow. No wheels, discs, straps, or belts shall be operated in such manner and in such direction as to cause the dust and dirt particles to be thrown into the operator's breathing zone.
Scratch-brush wheels and all buffing and polishing wheels mounted on floor stands, pedestals, benches, or special-purpose machines shall have not less than the minimum exhaust volume shown in Table D-57.2.

TABLE D-57.2 - BUFFING AND POLISHING WHEELS
Wheel diameter, inches (cm) Wheel width,
inches (cm)
Minimum exhaust
volume
(feet3/min.)
To 9 (22.86) 2 (5.08) 300
Over 9 to 16 (22.86 to 40.64) 3 (7.62) 500
Over 16 to 19
(40.64 to 48.26)
4 (10.16) 610
Over 19 to 24
(48.26 to 60.96)
5 (12.7) 740
Over 24 to 30
(60.96 to 76.2)
6 (15.24) 1,040
Over 30 to 36
(76.2 to 91.44)
6 (15.24) 1,200


Grinding wheels or discs for horizontal single-spindle disc grinders shall be hooded to collect the dust or dirt generated by the grinding operation and the hoods shall be connected to branch pipes having exhaust volumes as shown in Table D-57.3.

TABLE D-57.3 - HORIZONTAL SINGLE-SPINDLE DISC GRINDER
Disc diameter, inches (cm) Exhaust volume (feet3/min.)
Upto 12 (30.48) 220
Over 12 to 19 (30.48 to 48.26) 390
Over 19 to 30 (48.26 to 76.2) 610
Over 30 to 36 (76.2 to 91.44) 880
Where the work is outside the hood, air volumes must be increased as shown in American Standard Fundamentals Governing the Design and Operation of Local Exhaust Systems, Z9.2-1960 (section 4, exhaust hoods).
Grinding wheels or discs for horizontal double-spindle disc grinders shall have a hood enclosing the grinding chamber and the hood shall be connected to one or more branch pipes having exhaust volumes as shown in Table D-57.4.

TABLE D-57.4 - HORIZONTAL DOUBLE-SPINDLE DISC GRINDER
Disc diameter, inches (cm) Exhaust volume (feet3/min.)
Up to 19 (48.26) 610
Over 19 to 25 (48.26 to 63.5) 880
Over 25 to 30 (63.5 to 76.2) 1,200
Over 30 to 53 (76.2 to 134.62) 1,770
Over 53 to 72 (134.62 to 182.88) 6,280
Grinding wheels or discs for vertical single-spindle disc grinders shall be encircled with hoods to remove the dust generated in the operation. The hoods shall be connected to one or more branch pipes having exhaust volumes as shown in Table D-57.5.


TABLE D-57.5 - VERTICAL SPINDLE DISC GRINDER
Disc diameter, inches (cm) One-half or more of disc covered Disc not covered
Number1 Exhaust foot3/min. Number1 Exhaust foot3/min.
Up to 20 (50.8) 1 500 2 780
Over 20 to 30 (50.8 to 76.2) 2 780 2 1,480
Over 30 to 53 (76.2 to 134.62) 2 1,770 4 3,530
Over 53 to 72 (134.62 to 182.88) 2 3,140 5 6,010

   Footnote(1) Number of exhaust outlets around periphery of hood, or equal distribution provided by other means.
Grinding and polishing belts shall be provided with hoods to remove dust and dirt generated in the operations and the hoods shall be connected to branch pipes having exhaust volumes as shown in Table D-57.6.


TABLE D-57.6 - GRINDING AND POLISHING BELTS
Belts width, inches (cm) Exhaust volume (feet3/min.)
Up to 3 (7.62) 220
Over 3 to 5 (7.62 to 12.7) 300
Over 5 to 7 (12.7 to 17.78) 390
Over 7 to 9 (17.78 to 22.86) 500
Over 9 to 11 (22.86 to 27.94) 610
Over 11 to 13 (27.94 to 33.02) 740
Cradles and swing-frame grinders. Where cradles are used for handling the parts to be ground, polished, or buffed, requiring large partial enclosures to house the complete operation, a minimum average air velocity of 150 feet per minute shall be maintained over the entire opening of the enclosure. Swing-frame grinders shall also be exhausted in the same manner as provided for cradles. (See fig. D-57.3)
Grinding wheels on floor stands, pedestals, benches, and special-purpose grinding machines and abrasive cutting-off wheels shall have not less than the minimum exhaust volumes shown in Table D-57.1 with a recommended minimum duct velocity of 4,500 feet per minute in the branch and 3,500 feet per minute in the main. The entry losses from all hoods except the vertical-spindle disc grinder hood, shall equal 0.65 velocity pressure for a straight takeoff and 0.45 velocity pressure for a tapered takeoff. The entry loss for the vertical-spindle disc grinder hood is shown in figure D-57.1 (following paragraph (g) of this section).

TABLE D-57.1 - GRINDING AND ABRASIVE CUTTING-OFF WHEELS
Wheel diameter, inches (cm) Wheel width,
inches (cm)
Minimum exhaust
volume
(feet3/min.)
To 9 (22.86) 1½ (3.81) 220
Over 9 to 16 (22.86 to 40.64) 2 (5.08) 390
Over 16 to 19
(40.64 to 48.26)
3 (7.62) 500
Over 19 to 24
(48.26 to 60.96)
4 (10.16) 610
Over 24 to 30
(60.96 to 76.2)
5 (12.7) 880
Over 30 to 36
(76.2 to 91.44)
6 (15.24) 1,200

For any wheel wider than wheel diameters shown in Table D-57.1, increase the exhaust volume by the ratio of the new width to the width shown.

Example:

If wheel width = 4½ inches (11.43 cm), then (4.5/4) x 610 = 686 (rounded to 690).

Exhaust systems for grinding, polishing, and buffing operations should be designed in accordance with American Standard Fundamentals Governing the Design and Operation of Local Exhaust Systems, Z9.2-1960.
All exhaust systems shall be provided with suitable dust collectors.
Exhaust systems for grinding, polishing, and buffing operations shall be tested in the manner described in American Standard Fundamentals Governing the Design and Operation of Local Exhaust Systems, Z9.2-1960.
It is the dual function of grinding and abrasive cutting-off wheel hoods to protect the operator from the hazards of bursting wheels as well as to provide a means for the removal of dust and dirt generated. All hoods shall be not less in structural strength than specified in the American National Standard Safety Code for the Use, Care, and Protection of Abrasive Wheels, B7.1-1970.
Due to the variety of work and types of grinding machines employed, it is necessary to develop hoods adaptable to the particular machine in question, and such hoods shall be located as close as possible to the operation.
Swing-frame grinders shall be provided with exhaust booths as indicated in figure D-57.3.
Figure D-57.3 -- A Method of Applying an Exhaust Enclosure to Swing-Frame Grinders
Note: Baffle to reduce front opening as much as possible.
Portable grinding operations, whenever the nature of the work permits, shall be conducted within a partial enclosure. The opening in the enclosure shall be no larger than is actually required in the operation and an average face air velocity of not less than 200 feet per minute shall be maintained.
Vertical-spindle disc grinders shall be encircled with a hood so constructed that the heavy dust is drawn off a surface of the disc and the lighter dust exhausted through a continuous slot at the top of the hood as shown in figure D-57.1.
Figure D-57.1 -- Vertical Spindle Disc Grinder Exhaust Hood and Branch Pipe Connections

Dia. D inches (cm) Exhaust E Volume
Exhausted
at 4,500
ft/min
ft(3)/min
Note
Min. Max. No Pipes Dia.
20
(50.8)
1 4 ¼
(10.795)
500 When
one-half
or more
of the
disc can
be hooded,
use
exhaust
ducts as
shown at
the left.
Over 20 (50.8) 30
(76.2)
2 4
(10.16)
780
Over 30 (76.2) 72
(182.88)
2 6
(15.24)
1,770
Over 53 (134.62) 72
(182.88)
2 8
(20.32)
3,140
20
(50.8)
2 4
(10.16)
780 When no
hood can
be used
over
disc,
use
exhaust
ducts
as
shown
at left.
Over 20 (50.8) 20
(50.8)
2 4
(10.16)
780
Over 30 (76.2) 30
(76.2)
2 5 ½
(13.97)
1,480
Over 53 (134.62) 53
(134.62)
72
(182.88)
4 6
(15.24)
7
(17.78)
3,530

6,010
Entry loss=1.0 slot velocity pressure + 0.5 branch velocity pressure. Minimum slot velocity=2,000 ft/min -- ½-inch (1.27 cm) slot width.
Hoods for polishing and buffing, and scratch-brush wheels shall be constructed to conform as closely to figure D-57.4 as the nature of the work will permit.
Figure D-57.4

Standard Buffing and Polishing Hood
Wheel dimension, inches (centimeters Exhaust
outlet,
inches
(centimeters)
E
Volume
of air
at
4,500
ft/min
Diameter Width, Max
Min= d Max= D
9 (22.86) 2 (5.08) 3½ (3.81) 300
Over 9 (22.86) 16 (40.64) 3 (5.08) 4 500
Over 16 (40.64) 19 (48.26) 4 (11.43) 5 610
Over 19 (48.26) 24 (60.96) 5 (12.7) 740
Over 24 (60.96) 30 (76.2) 6 (15.24) 1,040
Over 30 (76.2) 36 (91.44) 6 (15.24) 7 1,200
Entry loss = 0.15 velocity pressure for tapered takeoff; 0.65 velocity pressure for straight takeoff.
Cradle grinding and polishing operations shall be performed within a partial enclosure similar to figure D-57.5. The operator shall be positioned outside the working face of the opening of the enclosure. The face opening of the enclosure should not be any greater in area than that actually required for the performance of the operation and the average air velocity into the working face of the enclosure shall not be less than 150 feet per minute.
Figure D-57.5 -- Cradle Polishing or Grinding Enclosure
Entry loss = 0.45 velocity pressure for tapered takeoff.
Hoods for horizontal single-spindle disc grinders shall be constructed to conform as closely as possible to the hood shown in figure D-57.6. It is essential that there be a space between the back of the wheel and the hood, and a space around the periphery of the wheel of at least 1 inch (2.54 cm) in order to permit the suction to act around the wheel periphery. The opening on the side of the disc shall be no larger than is required for the grinding operation, but must never be less than twice the area of the branch outlet.
Figure D-57.6 -- Horizontal Single-Spindle Disc Grinder Exhaust Hood and Branch Pipe Connections

Dia D inches (centimeters) Exhaust E
dia.
inches
(cm)
Volume
exhausted
at 4,500
ft/min
ft(3)/min
Min. Max.
12 (30.48) 3 (7.6) 220
Over 12 (30.48) 19 (48.26) 4 (10.16) 390
Over 19 (48.26) 30 (76.2) 5 (12.7) 610
Over 30 (76.2) 36 (91.44) 6 (15.24) 880

NOTE: If grinding wheels are used for disc grinding purposes, hoods must conform to structural strength and materials as described in 9.1.

Entry loss = 0.45 velocity pressure for tapered takeoff.
Horizontal double-spindle disc grinders shall have a hood encircling the wheels and grinding chamber similar to the illustrated in figure D-57.7. The openings for passing the work into the grinding chamber should be kept as small as possible, but must never be less than twice the area of the branch outlets.
Figure D-57.7 -- Horizontal Double-Spindle Disc Grinder Exhaust Hood and Branch Pipe Connections

Disc dia.inches
(centimeters)
Exhaust E Volume
exhausted
at 4,500
ft/min.
ft(3)/min
Note
Min. Max. No
Pipes
Dia.
19
(48.26)
1 5 610
Over 19 (48.26) 25
(63.5)
1 6 880 When
width "W" permits, exhaust ducts
should
be as
near heaviest grinding
as possible.
Over 25 (63.5) 30
(76.2)
1 7 1,200
Over 30 (76.2 53 (134.62) 2 6 1,770
Over 53 (134.62) 72
(182.88)
4 8 6,280
Entry loss = 0.45 velocity pressure for tapered takeoff.
Grinding and polishing belt hoods shall be constructed as close to the operation as possible. The hood should extend almost to the belt, and 1-inch (2.54 cm) wide openings should be provided on either side.
Figure D-57.8 -- A Typical Hood for a Belt Operation

Entry loss = 0.45 velocity pressure for tapered takeoff.

Belt width W. inches (centimeters) Exhaust Volume
ft.[1]/min
Up to 3 (7.62) 220
3 to 5 (7.62 to 12.7) 300
5 to 7 (12.7 to 17.78) 390
7 to 9 (17.78 to 22.86) 500
9 to 11 (22.86 to 27.94) 610
11 to 13 (27.94 to 33.02) 740
Minimum duct velocity = 4,500 ft/min branch, 3,500 ft/min main.
Entry loss = 0.45 velocity pressure for tapered takeoff; 0.65 velocity pressure for straight takeoff.
Exhaust hoods for floor stands, pedestals, and bench grinders shall be designed in accordance with figure D-57.2. The adjustable tongue shown in the figure shall be kept in working order and shall be adjusted within one-fourth inch (0.635 cm) of the wheel periphery at all times.
Figure D-57.2 -- Standard Grinder Hood

Wheel dimension, inches (centimeters Exhaust
outlet,
inches
(centimeters)
E
Volume
of air
at
4,500
ft/min
Diameter Width, Max
Min= d Max= D
9 (22.86) 1 ½ (3.81) 3 220
Over 9 (22.86) 16 (40.64) 2 (5.08) 4 390
Over 16 (40.64) 19 (48.26) 3 (7.62) 4 ½ 500
Over 19 (48.26) 24 (60.96) 4 (10.16) 5 610
Over 24 (60.96) 30 (76.2) 5 (12.7) 6 880
Over 30 (76.2) 36 (91.44) 6 (15.24) 7 1,200
Entry loss = 0.45 velocity pressure for tapered takeoff 0.65 velocity pressure for straight takeoff.
This paragraph (g), prescribes the use of exhaust hood enclosures and systems in removing dust, dirt, fumes, and gases generated through the grinding, polishing, or buffing of ferrous and nonferrous metals.
Spray-finishing operations are employment of methods wherein organic or inorganic materials are utilized in dispersed form for deposit on surfaces to be coated, treated, or cleaned. Such methods of deposit may involve either automatic, manual, or electrostatic deposition but do not include metal spraying or metallizing, dipping, flow coating, roller coating, tumbling, centrifuging, or spray washing and degreasing as conducted in self-contained washing and degreasing machines or systems.
A spray room is a room in which spray-finishing operations not conducted in a spray booth are performed separately from other areas.
Minimum maintained velocity is the velocity of air movement which must be maintained in order to meet minimum specified requirements for health and safety.
Spray booths are defined and described in 1926.66(a). (See sections 103, 104, and 105 of the Standard for Spray Finishing Using Flammable and Combustible Materials, NFPA No. 33-1969).
Spray booths or spray rooms are to be used to enclose or confine all operations. Spray-finishing operations shall be located as provided in sections 201 through 206 of the Standard for Spray Finishing Using Flammable and Combustible Materials, NFPA No. 33-1969.
Spray booths shall be designed and constructed in accordance with 1926.66(b)(1) through (4) and (6) through (10)(see sections 301-304 and 306-310 of the Standard for Spray Finishing Using Flammable and Combustible Materials, NFPA No. 33-1969), for general construction specifications. For a more detailed discussion of fundamentals relating to this subject, see ANSI Z9.2-1960.