Engine Exhaust Industry

The exhaust from all internal combustion engines, including diesel and gasoline powered engines, contains over 100 individual hazardous chemical components that, when combined, can create up to 10,000 chemical compounds. Many of these components are regulated. One of the biggest threats is carbon monoxide as it quickly poisons individuals and causes symptoms from headaches to comas or death. OSHA has a PEL of:

  • Carbon Monoxide: 35 ppm (parts per million) or 50 mg/m³

Another Major Component is sulfur dioxide (SO₂) which has adverse side effects such as fatigue and chronic bronchitis. OSHA's PEL is:

  • Sulfur Dioxide: 5 ppm (5 parts SO₂ per 1 million parts air)


Diesel Exhaust (DE) emissions include Diesel Particulate Matter (DPM) which has unique hazardous chemical components so it's regulated more strictly. OSHA has a partial list of chemicals associated with diesel exhaust and their corresponding documentation.

Here are some of the major components and their PELs:

  • Carbon Dioxide: 5,000 ppm or 9,000 mg/m³
  • Carbon Monoxide: 50 ppm or 55 mg/m³
  • Nitrogen Dioxide: (C) 5 ppm or 9 mg/m³
  • Nitric Oxide: 25 ppm or 30 mg/m³
  • Total Dust: 15 mg/m³
  • Sulfur Dioxide: 5 ppm or 13 mg/m³

(C) - Ceiling limit

Some of its minor components also pose a substantial threat. Here are some of these components and their PELs:

  • Acrolein: 0.1 ppm or 0.25 mg/m³
  • o-Anisaldehyde: 0.5 mg/m³
  • Benzene: 10 ppm
  • Formaldehyde: 0.75 ppm
  • Anthracene: 0.2 mg/m³
  • Naphthalene: 10 ppm or 50 mg/m³
  • Phenanthrene: 0.2 mg/m³
  • Pyrene: 0.2 mg/m³

As a result of all the hazardous chemical components, Diesel exhaust is also well known to be cancer causing or carcinogenic.

OSHA documentation  states that diesel fuel is designated as an OSHA Select Carcinogen.

The EPA states, "Diesel exhaust (DE) is likely to be carcinogenic to humans by inhalation from environmental exposures."

The NIOSH recommends that, "As prudent health policy, employers should assess the conditions under which workers may be exposed to diesel exhaust and reduce exposures to the lowest feasible limits."


Diesel Particulate Matter is important to monitor, too, as it had a set exposure limit by ACGIH for several years. They had set a threshold limit value for DPM and later changed it to a limit based on elemental carbon (which makes up about 40% of DPM) before removing it completely. 

  • Total DPM: 0.05 mg/m³
  • DPM (elemental carbon): 0.020 mg/m³


To view more regulations and recommendations for this industry, visit the following websites.

OSHA - Occupational Safety and Health Administration of the U.S. Department of Labor

ACGIH - American Conference of Governmental Industrial Hygienists

NIOSH - National Institute for Occupational Safety and Health

NFPA - National Fire Protection Association

EPA - United States Environmental Protection Agency

CSB - U.S. Chemical Safety and Hazard Investigation Board


Please note, this is a list of common applicable regulations, not a comprehensive list of all regulations applicable to this industry and may not reflect the latest publications.