Michaels - Particulate Matter



	Particulate Matter Definition: all types of airborne solid and liquid particles; sizes range from 0.005 – 100 microns [mm] Comparisons diameter human hair: 60-70 microns smallest visible: 20-30 microns Particles >30 microns unlikely to enter nasal passages Inhalable (thoracic) particles: <10 microns (PM10) Fine (respirable) particles: <2.5 microns (PM2.5) IH definition: < 4 microns (median cut-point) Ultrafine particles (UFP): <0.1 micron Mean increase in death rate from cardiovascular and respiratory causes was found to be 0.68% for each 10 ug/m³ increase in PM10 nNew England Journal of Medicine, Vol 343, No 24, Dec. 14, 2000 Larger fraction responds well to use of good HVAC filters, enhanced cleaning practice Vacuums with allergen filters; damp-wipe surfaces nSee: Berry, Michael A., Protecting the Built Environment: Cleaning for Health, Tricomm 21st Press, Chapel Hill, NC (1993) Fine and ultra-fine can be reduced by avoiding vehicle emissions and other combustion devices, source capture at printers, copiers nA portion of UFP will pass through HEPA filters: HEPA = 99.97% at 0.3 mm Sources include mechanical reduction (grinding), wind erosion, combustion (wildfires, I.C. engines, boilers), skin flakes, paper dust, insect parts, natural and synthetic fibers, industrial processes, smog, copiers and printers People emit large numbers of particles: 400,000 per minute sitting at a desk 45,000,000 per minute during exercise Particle surfaces will adsorb VOCs, oxidants Effective at delivering organics, toxics to lung tissues n UFP believed to overwhelm cleaning mechanism in alveoli (PAMs), damage epithelial cells, cause inflammation -- increases potential for bronchitis, asthma	Stay informed about current technologies and practices. Click here to subscribe to our FREE electronic News Briefs.



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