# 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 $\mu m$ (PM2.5) and up to 10 $\mu m$ (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 $mg/m^3$ - highest average concentration for any 8-hours period
• MAK
• PM2.5
• 1.5 $mg/m^3$ for particles less than 4 μm - highest average concentration for any 8-hours period
• PM10
• 4 $mg/m^3$ for particles less than 4 μm - highest average concentration for any 8-hours period

### Outdoor air regulatory levels

• U.S. EPA
• PM2.5
• 15 $\mu g/m^3$ - highest average concentration for any 1-year period
• 35 $\mu g/m^3$ - highest average concentration for any 24-hours period
• PM10
• 150 $\mu g/m^3$ - highest average concentration for any 24-hours period
• California
• PM2.5
• 12 $\mu g/m^3$ - the average concentration for any 1-year period which not to be exceeded
• PM10
• 50 $\mu g/m^3$ - the average concentration for any 24-hours period which not to be exceeded
• 20 $\mu g/m^3$ - the average concentration for any 1-year period which not to be exceeded
• Japan
• PM2.5
• 15 $\mu g/m^3$ - highest average concentration for any 1-year period
• 35 $\mu g/m^3$ - highest average concentration for any 24-hours period

## Reference levels

### Reference levels for industrial environments

• ACGIH
• PM2.5
• 3 $mg/m^3$ - highest concentration
• PM10
• 10 $mg/m^3$ - highest concentration

### General reference levels

• ASHRAE
• PM2.5
• 15 $\mu g/m^3$ - highest average concentration for any 8-hours period
• PM10
• 50 $\mu g/m^3$ - highest average concentration for any 8-hours period

### Indoor residential reference levels

• South Korea
• 150 $\mu g/m^3$
• 0.1 $mg/m^3$ - highest average concentration for any 1-hour period
• 0.04 $mg/m^3$ - highest average concentration for long term exposure