Clearing the Air: The Beginning and the End of Air Pollution

by Tim Smedley

But in terms of where we actually live, work and travel, we spend far more time on or near roads than we do standing next to power stations. Within towns and cities, our proximity to vehicles exposes us to the smallest particles that can enter into our bloodstream. Particulate number (PN) – the total number of particles in any given gulp of air, rather than the mass or weight of particles – is therefore the final piece of the particulate jigsaw. Unlike the background sources of urban air pollution, vehicle emissions occur at ground level and near to us humans breathing it all in. The very smallest of these particles, PM0.1 and below, known as ‘ultrafines’ or nanoparticles, are increasingly being linked to the worst health effects.

Proximity to roads and vehicles VS background sources