Occupational health and safety in the United States is enforced primarily by the federal Occupational Safety and Health Administration (OSHA) unless a state program is established such as in California or Michigan. Standards established and enforced by law are listed in Title 29 of the Code of Federal Regulations (CFR) for general industry in Part 1910, and construction in Part 1926. Mining operations are enforced by the federal Mine Safety and Health Administration (MSHA) and listed under Title 30 CFR. Many standards are similar between these agencies or CFR parts however, some differences do exist. It is important to know which standards are applicable to the production operations at a facility and know there are occasions where multiple regulatory agencies may have authority over a site.
With respect to general industry, the code includes the Z-tables which list Permissible Exposure Limits (PELs) for air contaminants which are legally-enforced by OSHA. Most PELs are expressed as 8-hour average airborne concentrations. Many current PELs were established when the Occupational Safety and Health Act of 1970 (OSH Act) was implemented and are therefore not aligned with current scientific studies or opinions with respect to acute or chronic toxicological impacts of occupational contaminants on the human body. Additionally, as enormous industrial advances and changes have occurred since 1970, many chemicals or other substances used in current industrial settings may not have PELs established.
OSHA may then enforce exposure limits established by other agencies such as the American Conference of Governmental Industrial Hygienists (ACGIH), the National Institute for Occupational Safety and Health (NIOSH) or the American Industrial Hygiene Association (AIHA). One of the more common set of limits used by Industrial Hygienists for sample result comparison purposes are the ACGIH Threshold Limit Values® (TLVs). Similar to PELs, these limits are typically expressed as 8-hour averages. These limits, while technically are advisory and not generally legally enforceable, they are representative of the latest opinions in scientific research regarding health effects of contaminants. Use of these limits are generally considered a "best-practice" but are occasionally referenced for issuing citations by OSHA if a PEL for the focus contaminant is not established. In this event, OSHA will likely issue citations as a violation of the General Duty Clause of the OSH Act in Section 5(a)(1). This section requires employers to provide a place of employment that is free from recognized hazards that are causing or likely to cause death or serious physical harm to employees. This section is subjective in nature and is frequently utilized for citation purposes related to workplace health and safety including monitoring results.
Noise-induced hearing loss is one of the most common work-related illnesses in the United States. The current general industry standard addressing noise is 29 CFR 1910.95 Occupational Noise Exposure. This standard can be somewhat cryptic and confusing to site management and employees. Please contact Nelson Industrial Hygiene with questions regarding the noise standard.
Essentially, the standard mandates the use of hearing protection devices for employees with measured noise exposures exceeding the PEL of 90 decibels, A-scale, as an 8-hour time-weighted average (dBA-TWA) which is also referred to as a 100% dose for an 8-hour shift.
If results exceed half of the PEL for an 8-hour shift (50% dose, 85 dBA-TWA), employers are not mandated to require the use of hearing protection but are required to provide it to employees. Additionally, employers are required to include these employees in a Hearing Conservation Program (HCP), as well as any employees with results exceeding the PEL. The HCP requires the establishment and upkeep of a written program, employee training, and baseline and annual audiograms, in addition to other provisions.
The most common tool used by the Industrial Hygienist for measuring employee noise exposure is the noise dosimeter. The noise dosimeter is worn by the employee throughout their work shift and integrates noise at certain levels related to Action Level or PEL compliance (threshold integration), and calculates the final dose percentage, TWA, and average for the run time of the dosimeter (Lavg). These devices are typically small, lightweight, and worn on the employee's shoulder near their ear.
Noise/sound mapping is another method of determining where noise intensity may be a problem or not. These maps are produced by physically recording sound levels on a facility map using a sound level meter. These maps are useful tools for visualizing areas or processes of concern and to develop strategies for the use of hearing protection or noise reduction. It should be noted though they are generally not accepted by OSHA for compliance with the standard. OSHA will typically require the results of noise dosimetry surveys to determine compliance with 29 CFR 1910.95 Occupational Noise Exposure.
Within Part 1910 for general industry, OSHA has established standards specific to certain substances. These substances are known to be carcinogens or possess other increased toxicological properties. These standards contain specific provisions to be followed by employers related to concentrations employees may be exposed to. It is important to have a thorough understanding of processes to know what types of unintended contaminants may be emitted. Examples of this are the inhalation and surface contaminant risks of hexavalent chromium from stainless steel welding/plasma cutting/arc gouging or the chronic toxicity from lead inhalation and ingestion by unknowingly melting lead-contaminated scrap metals in the foundry industry.
Some of the most common substances encountered in industry with established standards are hexavalent chromium (1910.1026), lead (1910.1025), formaldehyde (1910.1048), and respirable crystalline silica (1910.1053). Additionally, numerous other standards also exist such as methylene chloride, cadmium, inorganic arsenic, and benzene.
While there certainly are differences from standard to standard, most of them are generally similar in that they require the employer to determine and assess potential exposures, perform employee monitoring based on those exposure assessments, ensure monitoring is representative and covers all job classifications with potential exposures to the substance, repeat monitoring at scheduled frequencies based on results, and notifying participating and affected employees of monitoring results (usually within 15 days of receipt).
Also, if results exceed the PEL, the employer typically must establish and demarcate regulated areas, limit access to these locations, and prohibit any eating or drinking within these spaces. Additionally, the employer must use engineering and work practice controls to reduce contaminant concentrations consistently below the PEL, provide respiratory protection until controls are implemented or are demonstrated to not be feasible (some specify allowable respirator types to be used), provide medical surveillance to employees (some require this for results exceeding an Action Level instead of a PEL), conduct employee training, follow all hazard communication requirements, establish a written control program, and follow recordkeeping requirements.