Air Contaminants & Exposure Monitoring

The Occupational Safety and Health Administration (OSHA) has created air monitoring requirements to protect workers in the U.S. from health and safety risks due to air pollution at the workplace. Monitoring is conducted for comparison with established occupational exposure limits, such as the OSHA Permissible Exposure Limits (PELs) and American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs), or other established Occupational Exposure Levels (OELs).

Typically, air monitoring is needed for:

• Selecting personal protective equipment (respiratory protective equipment).

• Delineating areas where personal protection is needed.

• Assessing the health effects of potential exposure to airborne contaminants.

• Determining the need for specific, medical surveillance.

• Ensuring control measures are effective, or if further control measures are required.

• When OSHA has a substance specific standard (e.g., lead, methylene chloride, hexavalent chromium).

• When employees notice symptoms (e.g., irritation, odor) or complain of respiratory health effects.

• When the workplace contains visible emissions (e.g., fumes, dust, aerosols).

An industrial hygiene exposure assessment is the process of evaluating workplace exposure to airborne vapors, fumes, or particles of hazardous chemicals. A personal exposure assessment is used to determine the concentration, duration, and extent of a worker’s exposure to hazardous chemicals in the workplace. It can involve the use of both direct reading and personal measurement instruments, and are often necessary for initial or baseline evaluations.

The process involves:

• Review of Safety Data Sheets (SDSs) and chemical inventory;

• Review of workplace procedures and controls, and a determination of how the employees are affected by the chemicals on site;

• Collection of samples for analysis by an accredited laboratory or the use of direct reading instrumentation for real time results; and

• Preparation of written reports that includes the technical approach, results, conclusions, and recommendations, as appropriate to the findings. 

In addition to personal monitoring, area monitoring (stationary monitoring) can be used to measure the airborne concentration of a contaminant within the area to check if the control measures are effective, if further controls are required, or to indicate when entry to an area may be considered safe. For example, in a spray booth operation where adequate time is required to allow the local exhaust ventilation (LEV) to remove isocyanates and/or other dangerous substance present (e.g., VOCs such as toluene and methyl ethyl ketone) prior to entry.

EnHealth offers a wide variety of testing and monitoring for employee exposure and indoor air quality assessments, a sample of common work tasks that should be a part of an industrial hygiene monitoring program include:

• Work that creates nuisance dust and dusts containing hazardous components including coal dust, wood dust, and general environmental dust.

• Welding fumes associated with arc, MIG, TIG and gas welding.  Welding fumes contain a variety of metals, including aluminum, arsenic, beryllium, lead, and manganese. Argon, nitrogen, carbon dioxide, carbon monoxide, ozone, and hydrogen fluoride gases often are produced during welding.

• Hexavalent chromium fumes generated during the production or welding of chrome alloys.

• Work tasks that may produce respirable crystalline silica dust. Handling silica containing materials such as rock, concrete, brick, and mortar. Any high-energy operations such as cutting, sawing, grinding, polishing, drilling, and crushing stone that creates respirable crystalline silica.

• Spray painting operations should be evaluated because they are associated with a variety of different types of chemical exposures. Spray painters are commonly exposed to volatile solvents, isocyanates and to the pigment, which may contain harmful substances, such as hexavalent chromium.