PARTICULATE MATTER (PM)

Particulates are microscopic particles of solid or liquid matter suspended in the air. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health, in ways additional to direct inhalation.

Particle classification
- PM10 : inhalable particles, with diameters that are generally 10 micrometers and smaller; and
- PM2.5 : fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.

How small is 2.5 micrometers? Think about a single hair from your head. The average human hair is about 70 micrometers in diameter – making it 30 times larger than the largest fine particle.

Climate effects

Atmospheric aerosols affect the climate of the earth by changing the amount of incoming solar radiation and outgoing terrestrial longwave radiation retained in the earth's system. This occurs through several distinct mechanisms which are split into direct, indirect, and semi-direct aerosol effects. The aerosol climate effects are the biggest source of uncertainty in future climate predictions.

How to measure

Korea Meteorological Administration has installed Continuous Ambient Particulate Monitors at 31 locations nationwide, starting from 7 locations in 2003, and monitoring the concentration of PM10 in the atmosphere every 5 minutes. The measurement principle is as follows. Air is sucked through the inlet of the airborne dust analyzer, and aerosol particles with a diameter of 10 μm or less are deposited on the filter installed in the device. After shooting a beta ray emitted from the carbon isotope 14C into the filter area where the aerosol is collected, the attenuated beta ray is measured with a detector to calculate the PM10 concentration (μgm−3) per unit volume.

Mc: Mass concentration of fine dust in the atmosphere
X: mass density of collected dust
A: Sample collection filter area
Q: Sample collection flow rate
Δt: sample retake time
K: unit conversion factor