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Initial Assessments: A Safe Choice for Analyzing Exposure Levels

As an employer who is responsible for the safety and health of your employees, you need to determine if there are any occupational hazards present or likely to be present that may require employees to wear personal protective equipment (as required in 29 CFR 1910.132(d)(1)). Personal protective equipment, such as respirators and hearing protection devices, should be selected based on the occupational exposure levels found at the workplace. Therefore, an industrial hygiene initial assessment should be conducted to determine those levels.

Luis Pieretti

Luis Pieretti, Ph.D.

Safety and Health Consultant

There are toxic substances, like those listed in the table below, which have their own standard (Subpart Z, Toxic and Hazardous Substances). These particular substances require an initial assessment plus continual exposure monitoring, depending upon exposure levels found in the workplace. For an employer who handles these substances and has not performed any air monitoring at all, an OSHA compliance officer can cite the company for not performing the initial assessment, even if levels are found to be below the exposure limits.

Substance Requirement
Vinyl chloride – CAS 75-01-4

1910.1017(d)(1)

A program of initial monitoring and measurement shall be undertaken in each establishment to determine if there is any employee exposed, without regard to the use of respirators, in excess of the action level.

OSHA PEL 8-hr TWA 1 ppm, OSHA action level 8-hr TWA 0.5 ppm, STEL 5 ppm (15 minutes)

Inorganic Arsenic – CAS 7440-38-2

1910.1018(e)(1)(i)

Determinations of airborne exposure levels shall be made from air samples that are representative of each employee's exposure to inorganic arsenic over an eight (8) hour period.

1910.1018(e)(1)(iii)

The employer shall collect full shift (for at least 7 continuous hours) personal samples including at least one sample for each shift for each job classification in each work area.

1910.1018(e)(2)

Initial monitoring. Each employer who has a workplace or work operation covered by this standard shall monitor each such workplace and work operation to accurately determine the airborne concentration of inorganic arsenic to which employees may be exposed.

OSHA PEL 8-hr TWA 10 µg/m3, OSHA action level 8-hr TWA 5 µg/m3

Substance Requirement
Lead – CAS 7439-92-1

1910.1025(d)(1)(ii)

With the exception of monitoring under paragraph (d)(3), the employer shall collect full shift (for at least 7 continuous hours) personal samples including at least one sample for each shift for each job classification in each work area.

1910.1025(d)(1)(iii)

Full shift personal samples shall be representative of the monitored employee's regular, daily exposure to lead.

1910.1025(d)(2)

Initial determination. Each employer who has a workplace or work operation covered by this standard shall determine if any employee may be exposed to lead at or above the action level.

OSHA PEL 8-hr TWA 50 µg/m3, OSHA action level 8-hr TWA 30 µg/m3

Chromium VI (Hexavalent Chromium)

CAS -1333-82-0 (CrO3)

1910.1026(d)(2)(i)

The employer shall perform initial monitoring to determine the 8-hour TWA exposure for each employee on the basis of a sufficient number of personal breathing zone air samples to accurately characterize full shift exposure on each shift, for each job classification, in each work area. Where an employer does representative sampling instead of sampling all employees in order to meet this requirement, the employer shall sample the employee(s) expected to have the highest chromium (VI) exposures.

OSHA PEL 8-hr TWA 5 µg/m3, OSHA action level 8-hr TWA 2.5 µg/m3

Cadmium CAS - 7440-43-9 (metal)

1910.1027(d)(2)(i)

Initial monitoring. Except as provided for in paragraphs (d)(2)(ii) and (d)(2)(iii) of this section, the employer shall monitor employee exposures and shall base initial determinations on the monitoring results.

OSHA PEL 8-hr TWA 5 µg/m3, OSHA action level 8-hr TWA 2.5 µg/m3

Substance Requirement
Benzene CAS - 71-43-2

1910.1028(e)(2)(i)

Each employer who has a place of employment covered under paragraph (a)(1) of this section shall monitor each of these workplaces and work operations to determine accurately the airborne concentrations of benzene to which employees may be exposed.

1910.1028(e)(2)(ii)

The initial monitoring required under paragraph (e)(2)(i) of this section shall be completed by 60 days after the effective date of this standard or within 30 days of the introduction of benzene into the workplace. Where the employer has monitored within one year prior to the effective date of this standard and the monitoring satisfies all other requirements of this section, the employer may rely on such earlier monitoring results to satisfy the requirements of paragraph (e)(2)(i) of this section.

OSHA PEL 8-hr TWA 1 ppm, OSHA action level 8-hr TWA 0.5 ppm, STEL 5 ppm (15 minutes)

1,2-dibromo-3-chloropropane (DBCP)

CAS 96-12-8

1910.1044(c)(2)

Dermal and eye exposure. The employer shall assure that no employee is exposed to eye or skin contact with DBCP.

1910.1044(f)(2)

Initial. Each employer who has a place of employment in which DBCP is present, shall monitor each workplace and work operation to accurately determine the airborne concentrations of DBCP to which employees may be exposed.

1910.1044(f)(3)(i)

If the monitoring required by this section reveals employee exposures to be at or below the permissible exposure limit, the employer must repeat these measurements at least every 6 months.

1910.1044(f)(3)(i)

If the monitoring required by this section reveals employee exposures to be in excess of the exposure limit, the employer must repeat these measurements for such employee at least quarterly. The employer must continue quarterly monitoring until at last two consecutive measurements, taken at least seven days apart, are below the permissible exposure limit. Thereafter the employer must monitor at least every 6 months.

OSHA PEL 8-hr TWA 1 ppb (parts per billion)

Substance Requirement
Acrylonitrile CAS - 107-13-1

1910.1045(e)(2)

Initial monitoring. Each employer who has a place of employment in which acrylonitirile is present shall monitor each such workplace and work operation to accurately determine the airborne concentrations of acrylonitirile to which employees may be exposed.

OSHA PEL 8-hr TWA 2 ppm, OSHA action level 8-hr TWA 1 ppm, Ceiling 10 ppm (15 minutes).

Ethylene Oxide CAS – 75-21-8

1910.1047(d)(2)(i)

Each employer who has a workplace or work operation covered by this standard, except as provided for in paragraph (a)(2) or (d)(2)(ii) of this section, shall perform initial monitoring to determine accurately the airborne concentrations of EtO to which employees may be exposed

OSHA PEL 8-hr TWA 1 ppm, OSHA action level 8-hr TWA 0.5 ppm, Excursion limit 5 ppm (15 minutes)

Formaldehyde CAS – 50-00-0

1910.1048(d)(1)(i)

Each employer who has a workplace covered by this standard shall monitor employees to determine their exposure to formaldehyde.

OSHA PEL 8-hr TWA 0.75 ppm, OSHA action level 8-hr TWA 0.5 ppm, STEL 2 ppm (15 minutes)

Methylenedianiline (MDA) CAS – 101-77-9

1910.1050(e)(2)

Initial monitoring. Each employer who has a workplace or work operation covered by this standard shall perform initial monitoring to determine accurately the airborne concentrations of MDA to which employees may be exposed.

OSHA PEL 8-hr TWA 10 ppb, OSHA action level 8-hr TWA 0.5 ppb, STEL 100 ppb (15 minutes)

Substance Requirement
1,3 Butadiene CAS – 106-99-0

1910.1051(d)(2)(i)

Each employer who has a workplace or work operation covered by this section, shall perform initial monitoring to determine accurately the airborne concentrations of BD to which employees may be exposed, or shall rely on objective data pursuant to paragraph (a)(2)(i) of this section to fulfill this requirement. The initial monitoring required under this paragraph shall be completed within 60 days of the introduction of BD into the workplace.

OSHA PEL 8-hr TWA 1 ppm, OSHA action level 8-hr TWA 0.5 ppm, STEL 5 ppm (15 minutes)

Methylene Chloride CAS – 75-09-2

1910.1052(d)(2)

Initial determination. Each employer whose employees are exposed to MC shall perform initial exposure monitoring to determine each affected employee's exposure, except under the following conditions:

1910.1052(d)(2)(i)

Where objective data demonstrate that MC cannot be released in the workplace in airborne concentrations at or above the action level or above the STEL. The objective data shall represent the highest MC exposures likely to occur under reasonably foreseeable conditions of processing, use, or handling. The employer shall document the objective data exemption as specified in paragraph (m) of this section;

1910.1052(d)(2)(ii)

Where the employer has performed exposure monitoring within 12 months prior to April 10, 1997 and that exposure monitoring meets all other requirements of this section, and was conducted under conditions substantially equivalent to existing conditions; or

1910.1052(d)(2)(iii)

Where employees are exposed to MC on fewer than 30 days per year (e.g., on a construction site), and the employer has measurements by direct-reading instruments which give immediate results (such as a detector tube) and which provide sufficient information regarding employee exposures to determine what control measures are necessary to reduce exposures to acceptable levels.

OSHA PEL 8-hr TWA 25 ppm, OSHA action level 8-hr TWA 12.5 ppm, STEL 125 ppm (15 minutes)

Note: Coke oven emissions and cotton dust standards requirements are not included. This table only includes a fraction of the requirements stipulated in the OSHA standards. To review the complete standards, please visit the OSHA website.

PEL = Permissible Exposure Limit

STEL= Short Term Exposure Limit

TWA= Time-Weighted Average

Excurison in the Ethylene Oxide standard = The employer shall ensure that no employee is exposed to an airborne concentration of EtO in excess of 5 parts of ethylene oxide per million parts of air (5 ppm) as averaged over a sampling period of fifteen (15) minutes.

If you have any questions about how chemicals at your workplace or physical hazards, such as noise, can affect your employees, contact us for a free consultation. Remember, our services are confidential.