Micro-fine airborne pollutants: probably the most significant long-term pollution-related risk for city dwellers

Particles of partly combusted fuels and soot at the smallest size range (less than 2.5 microns, often called PM2.5 in measurement studies) come mainly from diesel engines and coal burning. They are probably the biggest health risk for residents of large cities worldwide today and should be a major concern for city dwellers in China. The main sources of these particles are ageing trucks and buses with poorly adjusted diesel engines. The soot particles are clearly visible in the black smoke from the exhaust. Industrial operations are another source.

The health effects of PM2.5 particles are beginning to be recognized by healthcare professionals, and they are a worldwide risk for city-dwellers. For example, this from a clinician writing in the Medical Journal of Australia recently:

“In Sydney, Melbourne, Brisbane and Perth, air pollution causes an estimated 1611 premature deaths every year, with more than 3000 estimated for Australia as a whole. The most serious health problems relate to fine particles (PM2.5), emitted predominantly by diesel-powered vehicles and woodheaters.”

The health risks of micro-fine soot particles stem from their ability to penetrate the lungs and pass into the bloodstream. This is the reason they are associated with cardiovascular disease (diseases of the heart and blood circulation) as well as lung disease. There are many research papers addressing this issue published and available online: the references below are a selection.

References and links for further reading

Fine particulate air pollution and hospital admission for cardiovascular and respiratory diseases, Dominici et al. JAMA. 2006 Mar 8;295(10):1127-34.
Templeton S-K. Urban cyclists raise their risk of heart disease. The Sunday Times [London] 2005; 21 Aug.
Clancy L, Goodman P, Sinclair H, Dockery DW. Effect of air-pollution control on death rates in Dublin, Ireland: an intervention study. Lancet 2002; 360: 1210-1214
Fine Particulate Air Pollution and Mortality in Nine California Counties: Results from CALFINE, Ostro et al, Environ Health Perspect. 2006 January; 114(1): 29–33. Full text available on-line.
The Association between Fatal Coronary Heart Disease and Ambient Particulate Air Pollution: Are Females at Greater Risk? Lie et al, Environ Health Perspect. 2005 December; 113(12): 1723–1729. Full text available online.

In addition to these references, many more studies can be found indexed online at Air Pollution Research News.