From: Particulate matter and atherosclerosis: role of particle size, composition and oxidative stress
Particle | Aerodynamic diameter (μm) | Sources | Mode of generation | Atmospheric half-life |
---|---|---|---|---|
Thoracic particles(PM10) | < 10 | - | - | - |
Coarse particles(PM2.5-10) | 2.5 - 10 | Suspension from disturbed soil (farming, mining, unpaved roads), construction, plant and animal fragments | Mechanical disruption (crushing, grinding, abrasion of surfaces), evaporation of sprays, suspension of dusts. | Minutes to hours |
Fine particles (PM2.5) | < 2.5 | Power plants, oil refineries, wildfires, residential fuel combustion, tailpipe and brake emissions | Gas-to-particle conversion by condensation, coagulation (accumulation mode) | Days to weeks |
Ultrafine particles (UFP) | < 0.1* | Fuel combustion (diesel, gasoline) and tailpipe emissions from mobile sources (motor vehicles, aircrafts, ships) | Fresh emissions, secondary photochemical reactions (nucleation mode) | Minutes to hours |