Agent Name

Particulate matter

Major Category

Other Uses

Synonyms

Particles suspended in air; PM; PM2.5; PM10; Ambient particulate matter (outdoor environmental); [Rom, p. 1487]

Category

Pyrolysis Products

Description

Particles smaller than 10 microns are designated PM10 fraction, and those <2.5 microns the PM2.5 fraction (the fine fraction). PM10 passes the larynx (thoracic fraction); PM2.5 reaches the alveoli (respirable fraction); [Levy, p. 532]

Sources/Uses

Natural (forest fires and volcanic eruptions) and related to human activity (anthropogenic); The main sources of PM2.5 are the combustion of fossil fuels (industry, transportation, and power plants) and biomass burning for heating and cooking. [PMID 20458016] Ultrafine particles (UFP) and nanoparticles are synonyms for particles less than 0.1 um (100 nm) in aerodynamic diameter. Workers exposed to PM2.5 with a high UFP component include boilermakers, welders, autoworkers, and workers exposed to emissions from asphalt, diesel engines, smelting, and high-speed grinding. [Reference #2] Workplace UFPs are generated by "hot" processes such as welding, grinding, smelting, soldering, laser ablation, cutting, polishing, and heat treating." [PMID 23348430]

Comments

For fine particulate, US air standards allow 15 ug/m3 annual average and 35 ug/m3 in a 24-hour period. Seventeen percent of US residents live in nonattainment areas for the annual average and 30% in nonattainment areas for the 24-hour standard. [Levy, p. 497] An Air Quality Index (AQI) of 0-50 is considered "Good" with no recommended restriction of athletic practice. An AQI of 0-50 corresponds to a PM2.5 <17.5 ug/m3 and a PM10 <75 ug/m3 as 24 hour averages. [Reference #1] The American Cancer Society (ACS) cohort was used in the most intensive study of air pollution mortality. After a follow-up period averaging eight years, the study of 151 US communities showed that PM2.5, but not PM10, was associated with cardiovascular and lung cancer mortality. Long-term instillation of particulate matter into the airways of rabbits increases coronary atherosclerosis. [Rom, p. 1498-1500] Studies have established that exposure to ambient air pollution (especially PM2.5 from combustion sources) increases the risk of cardiovascular disease. ". . . recent studies of daily cardiopulmonary mortality and biomarkers of platelet activation suggest that UFP (PM0.1) may be more toxic than PM2.5." [Reference #2] ". . . regulatory standards, based on mass concentration, may not be effective in protecting the health and safety of workers if UFP exposures exist, because the mass concentration of UFPs is often negligible compared with that of larger particles. . . . Unfortunately, it is not yet clear which key particulate parameters (mass, surface area, number, and size distribution) would be the most relevant measurements with regard to health in workplace. This uncertainty stems from the scant and at times contradictory, toxicological information currently available regarding UFPs." [PMID 23348430] Also see "Lessons from air pollution epidemiology for studies of engineered nanomaterials." [PMID 21654423]

Reference Link

EPA Air Quality Index (AQI): A Guide to Air Quality and Your Health

Exposure Assessment
Reference Link

Epidemiologic challenges for studies of occupational exposure to engineered nanoparticles; a commentary.

Links to Other NLM Databases
Toxicity Information

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