Research published in the journal Atmospheric Environment, describes how the team from Imperial College London and the Health and Safety Laboratory, Buxton, measured and visualised exposure to pollution levels, while using a variety of different transport methods for travelling across London.

The researchers looked at five modes of transport, including walking, cycling, car, taxi and bus, and measured levels of exposure to ultrafine particles when travelling on them using a newly developed system that uses in combination an ultrafine particle counter and video recorder.

Ultrafine particles are less than 100 nanometres in diameter and mainly traffic related. Their small size and large surface area means it is possible to inhale large quantities which makes them particularly dangerous.

The visualisation system allows video images of individuals' activities to be played back alongside the ultrafine particle concentrations they are exposed to. As a result, most activities and behaviours that cause high exposures can be visibly identified, such as being trapped on traffic islands and waiting in congested traffic.

On average, while travelling in a taxi, passengers were exposed to over 100,000 ultrafine particles counts per cubic centimetre (pt/cm3), travelling in a bus resulted in exposure to just under 100,000 pt/cm3, travelling in car caused exposure to 40,000 pt/cm3, cycling was around 80,000 pt/cm3, and walking was just under 50,000 pt/cm3.

Surbjit Kaur, from Imperial College London, and first author of the paper, said: "It was a real surprise to find the extent to which walking resulted in the lowest exposure. The higher exposure from travelling in taxis may come from actually sitting in the vehicle whi
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Contact: Tony Stephenson
at.stephenson@imperial.ac.uk
44-207-594-6712
Imperial College London
10-Jan-2006