‘When you talk about ambient particle exposure, there are two things you need to think about: one is the overall background levels, and that is going to be dominated by meteorological factors, which way the wind’s blowing and where it is blowing from … and yes it can be transported from miles away. But when we’re talking about city traffic, the particles are generated on the road, and they disperse quite quickly. It’s an exponential decay, usually from the roadside.
Types of ambient particle exposure
