Particles

Background

Particles may be solid matter or liquid droplets. Particles are measured in micrometres which equals 1/1000 of a millimetre. PM₁₀ (particles of 10 micrometres in size) and smaller particles are small enough to penetrate deeply into the lungs. Visibility reduction due to fine particles are measured as airborne particle index (API).

Health effects

Particles can aggravate existing respiratory and cardiovascular disease resulting in increased hospital admissions, emergency room visits and increases in daily mortality. Decreases in lung function, exacerbation of asthma and alteration in the body's defence mechanisms and lung clearance mechanisms have also been associated with airborne particles. Sensitive subgroups of the population include the elderly, children and people with existing respiratory or cardiovascular disease.

Sources

Particles are emitted from industrial processes, motor vehicles, domestic fuel burning and industrial and domestic incineration. Volcanoes, bushfires, windblown dust and the oceans are all natural sources of particles. Particles result from all sorts of combustion.

Current standards

The current one-day standard for PM₁₀ is 50 micrograms per cubic metre. One-hour standard for visibility reducing particles (minimum visual distance) is 20 kilometres.

Goal

Maximum allowable exceedences for PM₁₀ should be five days a year. Visibility reduction to 20 kilometres or below should be three days a year.

Top