Road user exposure to air pollution

Extras din raportul ETA (the Environmental Transport Association)

The car has become an integral part of modern society – it has brought us flexibility, freedom and mobility. However, there is a growing recognition of the problems that our dependence on the car has brought – air and noise pollution, congestion and growing social exclusion for those who do not own cars. Most people recognize that action in these areas is essential, and many are prepared to take it. However, for many others, public transport remains something for other people to use, and reducing car dependency a problem for other people. Cycling and walking too are seen as modes of transport for the young or the poor, and the health risks of walking or cycling on polluted roads are generally seen as being high.

This review of the literature on the exposure to pollution of various road users by EEP and ETA provides a vital counterbalance to these beliefs. In a careful and detailed analysis of recent studies, the review shows that cars offer little or no protection against the pollutants generated by road traffic. Indeed most studies indicate that drivers and passengers in cars are exposed to higher levels of pollutants than pedestrians and cyclists – and that even users of other methods of public transport tend to be exposed to lower levels than car users. They also show that, contrary to popular belief, pedestrians generally experience the lowest levels of exposure of all road users.

This paper updates and significantly extends an earlier literature review of car occupant exposures by reviewing recent studies which compare the levels of vehicle-derived pollutants found inside and immediately outside motor vehicles and, in many cases, compare these to background levels. Consideration is also given to exposure of other road user groups such as cyclists and pedestrians.

The research indicates clearly that: cars offer little or no protection against the pollutants generated by vehicle traffic. Road users can be exposed to significantly elevated levels of pollutants as they are, in effect, traveling in a ‘tunnel’ of pollution. Those road users traveling closest to the centre of this tunnel tend to experience higher concentrations of pollutants than those nearer to the roadside. Studies from Britain, continental Europe and the United States agree that in-vehicle levels of the vehicle-derived pollutants benzene (and other hydrocarbons), carbon monoxide, and nitrogen dioxide are substantially elevated above the levels of these pollutants found in air at a distance of around 50-100 metres from the vehicle, whereas levels of non-vehicle derived pollutants vary far less. Typical indicative values for average concentrations relative to background levels are shown in the table below. Most of the studies indicate that drivers and passengers in motor vehicles are exposed to higher levels of these pollutants than pedestrians and cyclists.

The factors exacerbating the interior levels of VOCs and CO in cars seem to be dense, slow-moving traffic, stable air, increased vehicle age, and faulty exhaust systems. Typical urban rush-hour conditions tend to produce the highest in-car concentrations of these pollutants. The in-vehicle levels of nitrogen oxides, on the other hand, seem to be worse during motorway driving, and levels of NO2 in particular seem to rise later in the day. Interestingly, in most studies the level of ventilation did not significantly alter interior concentrations, although conditions tended to be worse with the heater or ventilation on and sometimes better (for VOCs) with air conditioning in use.  Other transport-related environments are also found to have distinctive pollution characteristics. Open-air car parks generally have relatively low levels of pollution, but enclosed car parks appear to retain the pollution caused by vehicles, and high levels have been recorded. Vehicle filling stations also expose drivers to high levels of VOCs unless sophisticated vapour-recovery systems are fitted.

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3 Responses to “Road user exposure to air pollution”

  1. me Says:

    ce-mi place mie cand noi dam extracte din rapoartele americanilor :) … mai stati si mai rumegati inainte de a scrie lucruri care nu se aplica peste tot in lumea asta…

  2. mishtone Says:

    Ce-mi place mie cand se apuca unii sa vorbeasca aiurea…

    In primul rand, daca citeai cu atentie articolul, vedeai ca se refera la “Studies from Britain, continental Europe and the United States” (para 4).

  3. jocuri barbie Says:

    @mishtone ai dreptate ….

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