Which transport option is the healthiest?
Transport is the main contributor to air pollution in our cities, and how we move around in them can have huge consequences for how much air pollution we are exposed to. The Healthy Air Campaign teamed up with King’s College London, Camden Council and London cyclist, Vivienne Westwood, to see what travel options are the healthiest.
Six volunteers travelled from the same starting point (Lincoln’s Inn Fields) to the same end point (Castlehaven Community Centre) during a Friday afternoon rush hour in May. Four travelled the same direct route along busy Kingsway, Southampton Row, Eversholt Road and into Camden Town using different modes of transport: walking, cycling, bus and car. The other two walked and cycled an alternative route along quieter streets and a canal footpath. Each volunteer carried a personal air pollution monitor to record their exposure.
We used micro aethalometers* to measure the levels of black carbon (soot) that each volunteer was exposed to, as they travelled on their journey. These are ultrafine particles released by the burning of fossil fuels, such as in vehicle engines and, in particular, diesel vehicles. The micro aethalometers measured the levels of black carbon emitted by the passing traffic.
If asked to think about the problem of air pollution in cities, you might picture pedestrians and cyclists wearing masks to protect themselves from breathing in harmful fumes. So you might be surprised that in our experiment the highest levels of air pollution were recorded by the person in the car, followed by the person travelling by bus. In fact, the car driver was exposed to more than twice the amount of air pollution as the person walking the same busy route, and almost eight times more pollution than the cyclist.
The reason for this is that the vehicles were travelling in a queue of traffic that produced a stream of air pollution from the vehicles directly in front. This air pollution was brought in through the ventilation systems and trapped within the vehicles, resulting in higher concentration levels.
Meanwhile, the pedestrian was walking to the side of the sources of air pollution and so was exposed to much lower concentration levels and, although taking longer, half the amount of air pollution as the person in the car. The cyclist sharing the same road as the car was most likely able to avoid the higher concentration levels of pollution by not always being directly behind the vehicle in front and because the air was able to circulate freely around them. The cyclist was 13 minutes quicker than the car, and was exposed to an eighth of the pollution.
The lowest pollution levels were experienced by the volunteers on the alternative quiet routes, away from busy road traffic. In particular, the person walking the quiet route was exposed to a third of the pollution as the person walking the busier route. For the cyclists, the difference was most noticeable in the average levels of pollution that were 30% lower for the quieter route.
More benefits to walking and cycling
Our real-world experiment shows that getting more people walking and cycling around our cities not only reduces air pollution but can help reduce how much pollution they are exposed to.
Taking quieter, alternative routes will help drastically reduce your exposure to air pollution, and can also be more pleasant experiences.
However, this is not a sustainable option. People shouldn’t feel the need to wear masks, or have to go out of their way to avoid air pollution. The Healthy Air Campaign is demanding drastic action. Sign up, and help us push the Government to take ambitious action to reduce air pollution.
*Many thanks to Air Monitors Ltd and City of London for loaning us the equipment.