Shanghai, Moscow and Tehran have been named the cities with the highest levels of nitrogen dioxide (NO2) air pollution in the world. This conclusion was reached by the American non-profit organization Health Effects Institute and the research institute Institute for Health Metrics and Evaluation in a report for The State of Global Air.
Fourth place in this indicator was taken by another Russian city - St. Petersburg. The top ten also includes Chinese Beijing, Egyptian Cairo, Turkmen Ashgabat, Belarusian Minsk, Turkish Istanbul and Vietnamese Ho Chi Minh City.
Pallavi Pant, a senior researcher who supervised the study, admitted that he was surprised that several Russian cities appeared in the top of the ranking. “Most likely, this result is associated with emissions from traffic and an outdated vehicle fleet,” the expert explained.
The scientists noted that, unlike PM2.5 fine particles in the atmosphere, the problem of NO2 emissions is little studied - this is due to the lack of ground-based monitoring stations capable of detecting the gas.
According to the researchers, nitrogen dioxide is not as life-threatening as PM2.5. However, it can provoke various respiratory diseases, including the development of asthma in children. The main source of NO2 are vehicles with internal combustion engines, and the greatest harm, according to experts, comes from old cars.
At the same time, the highest level of PM2.5 particles released into the air from the use of coal-fired power plants, waste incineration and from transport was recorded in Indian Delhi and Kolkata. Following them in terms of the scale of this type of pollution are the Nigerian Kano and the Peruvian Lima.