Using TfL data to better understand Londoners exposure to air pollution
Studies that estimate the harmful effects of air pollution are based on methods, which assume that we only breathe in the air in our local neighbourhoods. But how much time do people actually spend there? Using anonymous activity data (provided by Transport for London ), and advanced air pollution and micro-environmental modelling, we have built the London Hybrid Exposure Model (LHEM) to begin to look at this problem from a different angle. We have looked at where Londoners spend their time, and the air that they are breathing whilst in these places.
Our findings show that, on average, many studies are over-estimating Londoners exposure to outdoor air pollution, but that there are also many people whose exposure is being under-estimated. These people tend to spend long periods in transport, such as in the car or on the bus, where they are exposed to high levels of NO2 and PM2.5 . We also conclude that since most people spend a lot of time indoors that sources of pollution in the home, office or school are very important in estimating peoples exposure to air pollution, but that this is not currently considered in the studies of people’s health.
There is more work to do to better disentangle exposure to air pollution and its health effects, but we hope that this is a step in the right direction.
Below we have taken a subset of 45,000 Londoners and have created some interactive graphs for you to explore. Data within the graphs is labelled 'LHEM' for showing results from our new exposure model, and 'residential' for the same people’s exposures in their local neighbourhood.
The raw data is available here.
The London Hybrid Exposure Model (LHEM): Improving human exposure estimates to NO2 and PM2.5 in an urban setting
James David Smith, Christina Mitsakou, Nutthida Kitwiroon, Ben M. Barratt, Heather A Walton, Jonathon G Taylor, Hugh Ross Anderson, Frank J. Kelly, and Sean D. Beevers. 2016. Environmental Science & Technology