The driver was the most exposed to pollution.
Dean, who spends up to 9 hours a day driving in central London, had the highest levels of exposure overall. This is because pollution can collect and circulate inside vehicles, especially when in traffic. It’s a common misconception that cyclists and pedestrians are likely to face the worst air - this suggests that’s not the case.
The outdoor worker was much more exposed than people in modern offices.
Ashley, who works as a site engineer in Kings Cross was 6 x more exposed than someone who works in an office environment with clean air. This suggests outdoor workers are more at risk to the effects of air pollution. Modern office buildings with efficient filter systems tend to have good air quality. In leakier older buildings the quality of air may be poorer, especially if located next to busy roads.
Taking back routes significantly reduces your exposure to pollution.
Dharmika reduced her exposure by 1/3 by choosing to walk back route between Kings Cross and Mayfair, instead of going down Oxford Street. This agrees with other research which suggests taking back-routes can reduce exposure by 50% on average. Taking routes which have less traffic or travelling at different times of the day can make a significant difference to personal exposure.
Pollution levels spiked on the tube
Everyone experienced the highest concentrations of particles when on the tube.
The deeper lines were worse than those closer to the surface, with trains over ground being 10 times cleaner. The types of particles underground are different to those over ground. Tube dust is mostly iron oxide, which comes from tyre and brake-wear. The impact on iron oxide on health is still not yet fully understood.