Particular particles and pollution

Dirt, dust and grime are familiar to city dwellers. But tiny airborne particles produced by road traffic, especially in highly polluted urban areas, can be a risk to health. Just how much of a risk is the subject of a talk to be given by Birgit Krausse, of the Institute of Energy and Sustainable Development at De Montfort University Leicester, at the Urban Air conference in Prague on Wednesday 26 March. Her findings suggest that current air-quality standards ignore a major component of pollution that could be seriously damaging our health.

Particulates from diesel exhausts and road dust, known as PM10 and PM2.5, have been shown to have short and long-term effects on the lungs and heart. Less well known is that the much smaller particles, “ultra-fines” from petrol engines, may be even more dangerous because they can penetrate deeper into the lungs and react with body cells. “The underlying biological mechanisms of the effects of particle pollution on health are not yet understood,” Krausse explained, “and health studies mainly rely on statistical relationships between measured particle concentrations and health effects.”

Krausse and her colleagues are carrying out a study of typical urban driving routes in the city of Leicester. The study will determine the degree to which drivers are exposed to particle emissions. Environmental monitoring equipment aboard an electric vehicle is used to collect air pollution data – particle mass and number concentrations, as well as carbon monoxide levels – inside the driver’s cabin, while the driver records the traffic conditions on a dictation machine. The data is then analysed to produce a second-by-second profile of the driver’s exposure to traffic pollution. “Normally, personal exposure studies are averaged over a long period of time so specific time dependent details are not available”, explained Krausse. “Our data set has a short averaging time of a second so we can see how much higher peak values are and how frequently they occur.” Krausse added that, “The preliminary findings suggest that averages simply don’t tell the whole story.”

Krausse’s data plots also show patterns that are related to traffic events such as being stuck in a traffic jam or behind an old, and probably more polluting, car. These events will be discussed at the conference along with how the weather affects pollution values.