Particulate Matter

All particles of solid and liquid substances which contained in the air form Particulate Matter (PM). Examples of PM are soot and smoke from engine or boiler exhausts, dust, volatile moisture, pollen etc.

Particulate Matter concentration limitations are set for two classes of particles: up to 2.5 (PM2.5) and up to 10 (PM10). The size of particles determines their movability and infiltration ability. Smaller particles are able to stay suspended in the air for a longer time and infiltrate more active than bigger particles. Generally, PM2.5 is more hazardous than PM10.

Regulatory levels

Regulations for industrial environments

  • OSHA:
    • PM2.5
      • 5 - highest average concentration for any 8-hours period
  • MAK
    • PM2.5
      • 1.5 for particles less than 4 μm - highest average concentration for any 8-hours period
    • PM10
      • 4 for particles less than 4 μm - highest average concentration for any 8-hours period

Outdoor air regulatory levels

  • U.S. EPA
    • PM2.5
      • 15 - highest average concentration for any 1-year period
      • 35 - highest average concentration for any 24-hours period
    • PM10
      • 150 - highest average concentration for any 24-hours period
  • California
    • PM2.5
      • 12 - the average concentration for any 1-year period which not to be exceeded
    • PM10
      • 50 - the average concentration for any 24-hours period which not to be exceeded
      • 20 - the average concentration for any 1-year period which not to be exceeded
  • Japan
    • PM2.5
      • 15 - highest average concentration for any 1-year period
      • 35 - highest average concentration for any 24-hours period

Reference levels

Reference levels for industrial environments

  • ACGIH
    • PM2.5
      • 3 - highest concentration
    • PM10
      • 10 - highest concentration

General reference levels

  • ASHRAE
    • PM2.5
      • 15 - highest average concentration for any 8-hours period
    • PM10
      • 50 - highest average concentration for any 8-hours period

Indoor residential reference levels

  • South Korea
    • 150
  • Canadian regulations
    • PM2.5
      • 0.1 - highest average concentration for any 1-hour period
      • 0.04 - highest average concentration for long term exposure

Particulate Matter sensors are gaining more popularity currently, mostly as part of Air Quality Monitoring system. Such system indicate the how polluted the air is and useful in determining the effectiveness of indoor ventilation and filtration.