diesel exhaust

In-car air pollution for drivers minimised via smarter ventilation settings

Following “cleaner” routes and ensuring that a vehicle’s ventilation system is set effectively can be enough for drivers and passengers to avoid the worst air pollution, a study has found.

Various respiratory conditions and other health problems can be triggered from the nitrogen oxides (NOx) and particulate matter (PM) that are commonly emitted from vehicle exhausts.

Outdoor air pollution is estimated to contribute to 40,000 deaths in Britain annually and an estimated seven million deaths globally, linked to diseases ranging from lung cancer to stroke and respiratory infection.

Recent figures from the European Environment Agency suggested that around 400,000 premature deaths occurred in Europe in 2016 as a result of air pollution. Conversely, the recent respite due to lower volumes of traffic, following continent-wide lockdowns in response to the coronavirus pandemic, is estimated to have saved around 11,000 lives.

A team from the University of Birmingham have found that if vehicle ventilation is set correctly, drivers and passengers are exposed to up to 49 per cent less PM2.5 and 34 per cent less Nitrogen Dioxide (NO2) than the on-road levels.

Lead author of the study Dr. Vasileios Matthaios said: “Exposure to air pollution within the vehicle depends upon both the ventilation setting and the type of route. The lowest exposure to particles and gases is when the windows are closed with recirculation and air conditioning switched on.

“Drivers and passengers inhale more air pollution when traveling on urban roads, followed by ring roads and suburban roads. However, because concentrations inside a vehicle are lower and occupants are not as active, they inhale less air pollution than people cycling or walking on the same routes.”

Researchers explored within-vehicle levels of NO2 and PM2.5 under different vehicle ventilation settings and driving routes during real-world driving experiments around the city of Birmingham.

Four vehicles were driven on a consistent route of three contrasting road types, measuring simultaneous within-vehicle and ambient levels of particulate matter (PM10, PM2.5, PM1); ultrafine particles number (UFP); lung surface deposited area (LSDA); nitric oxide (NO) and nitrogen dioxide (NO2).

“Our findings show that vehicle passengers can modify their exposure and inhalation dose through ventilation setting and route choice. This may have significant health impacts upon the most exposed groups, such as professional drivers,” Matthaios said.

Increasing urbanisation, together with growth in vehicle ownership and passenger journeys, have contributed to the growth in traffic-related ambient air pollution.

Researchers noted that related health issues depend on an individual’s exposure to air pollution and the vulnerability of the individual to a given dose. This, in turn, depends on route selection; time of day; transport type; respiration rate and, in the case of vehicles, ventilation options and efficacy and type of cabin filters.

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