Opening car windows for ventilation risk to users’ health

Car driver
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Speed read

  • Researchers assessed in-car air pollution in ten cities in low- and middle-income nations
  • The three cities in Sub-Saharan Africa showed higher in-car air pollution than their counterparts
  • Expert call for African policymakers to enforce transport regulations

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[NAIROBI] Car users in some of the world’s poorest cities experience higher levels of in-car air pollution with serious health consequences because of their tendency to open car windows for ventilation, a study has found.

According to estimates by the World Health Organization, outdoor air pollution caused 4.2 million premature deaths in 2016, with the deaths resulting from the inhalation of particulate matter — solid and liquid particles suspended in the air, many of which are hazardous and cause diseases such as cancer and heart-related illnesses.
Transport is a major source of air pollution in Sub-Saharan African countries and it is on the rise due to, among others, the growth of ageing vehicle fleet, high proportions of polluting two-stroke engine vehicles, the lack of emission controls on vehicles, and poor monitoring and enforcement system, according to another study.
The researchers say that most studies on outdoor air pollution do not look specifically at low-and middle-income cities, thus their motivation to conduct the study in ten of such cities: Addis Ababa, Ethiopia; Blantyre, Malawi; Cairo, Egypt; Chennai, India; Dar-es-Salaam, Tanzania; Dhaka, Bangladesh; Guangzhou, China; Medellín, Colombia; São Paulo, Brazil and Sulaymaniyah, Iraq.

“The level of PM particulate matter [pollution] in low-income African countries is way above the limit set by the World Health Organization.”

Araya Asfaw, Addis Ababa University in Ethiopia

The study found that car users in low-income cities who open their windows for ventilation are exposed to 80 per cent more air pollution than their counterparts who close their car windows.
“More than 90 per cent of pollution-related deaths occur in low- and middle-income countries such as Ethiopia with children at high risks of pollution-related and premature deaths,” says Araya Asfaw, a co-author of the study and an associate professor at the Department of Physics, Addis Ababa University in Ethiopia.
Asfaw adds that particulate matter concentrations varied across the ten cities but African and Asian cities were relatively higher in exposure compared with Latin American and Middle Eastern cites. 
“The level of particulate matter [pollution] in low-income African countries is way above the limit set by the World Health Organization,” says Asfaw, adding that the limit is daily exposure of 25 microgram per meter cube.

 “Consequently, car users in these countries are exposed to high level of pollution…increase [in] diseases and premature deaths associated with it.”
Researchers collected data between February and December 2019, aaccording to the study published in the Science of the Total Environment this month (1 August).
The scientist conducted a total of 540 runs, which covered 507 hours over a distance of 573 km across all cities, with car routes selected to include similar urban exposure scenarios including commercial areas and heavy traffic roads. In each city, the very same passenger car was used for all runs to cover at least ten kilometres. They also measured the pollution level of each city and assessed exposure of different scenarios including opened windows to pollution.
Regardless of the car model used and the city, windows-open setting showed the highest exposure, with Addis Ababa recording the highest exposure to pollution among all cities when during peak morning hours, followed by Blantyre (Malawi’s capital city) and Dar-es-Salaam, the study says.

Asfaw adds that car users in Sub-Saharan Africa should care about the study’s findings because of their health and wellbeing while the general public can use the study findings to put pressure on policymakers to enforce regulations, especially in the public transport sector.Andriannah Mbandi, a research fellow at the Stockholm Environment Institute Africa, who was not involved in the study, says that as the demand for transportation in cities increases in Africa, with the middle class buying more and mostly second-hand cars, exposure to air pollution in their cars will increase.
“Pollution also affects those who rely on public transport in Africa. The buses and mini-buses ferrying millions of commuters on the continent don’t often have air conditioners, and [are] often forced to open windows for circulation,” she says.
“Indoor air pollution such as the one we are exposed to in our households, cars and workplaces is a big challenge in Africa.”
This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.


[1] Prashant Kumar and others In-car particulate matter exposure across ten global cities (Science of the Total Environment, 1 August 2020)
[2] Ambient (outdoor) air pollution (WHO, May 2018)