The world's biggest and most populous cities face some of the most hazardous health threats due to their declining air quality, according to a new report by the US-based research organization Health Effects Institute. Released on Wednesday, the Air Quality and Health in Cities report, as part of the State of Global Air Initiative, says that Exposure to unclean air can cause a multitude of health problems – from an increased risk of asthma, lung diseases, heart problems, type 2 Diabetes and respiratory infections to premature births and more. Air pollution is responsible for 1 in 9 deaths worldwide and accounted for 6.7 million deaths in 2019 alone.
The new report analyses air pollution and global health effects for more than 7,000 cities around the world, focusing on two of the most harmful pollutants: fine particulate matter (PM2.5) and nitrogen dioxide (NO2). While Delhi, India was the most polluted city with the highest PM2.5 levels, Shanghai, China had the highest levels of NO2 pollution.
The burning of fuel from older cars, power plants, industrial facilities, as well as domestic cooking and heating, all emit NO2, while PM2.5 is the result of the burning of fossil fuels like coal and wood in low and middle-income countries.
Inhaling high levels of NO2 over time is related to cardiovascular diseases in adults and respiratory problems in children. As city residents tend to live closer to roads with dense traffic, their chances of exposure to NO2 increases more than that of residents in rural areas. Long-term exposure to PM2.5 pollution is associated with illness and early death from a variety of diseases including strokes, lung cancer, pneumonia, type 2 diabetes, and adverse birth outcomes.
The data from 2010 to 2019 revealed that there are striking differences between the global patterns of exposure to the two air pollutants: while exposure to PM2.5 pollution tends to be higher in cities found in low- and middle-income countries, exposure to NO2 is high across cities in both high- and low-income countries, the report adds.
However, trends in air quality levels have been positive for some countries. In Europe, for example, setting up low-emission zones (LEZs) in more than 300 cities has proved to show a decline in traffic air pollution. In Beijing, China, strict controls over coal-fired power plants, and stringent controls over vehicle emissions and fuel quality have been implemented. These policies have resulted in the city’s annual average PM2.5 level in just five years, the repo.
The report also proposed the key to understanding and addressing the health effects of air pollution. According to the WHO’s Air Quality Database, only 117 nations currently have ground-level monitoring systems to track PM2.5, and only 74 nations are monitoring NO2 levels. Investing in air quality monitors and tracking devices would be a significant asset for countries. Collecting, analysing and keeping a record of air quality reports can help governments come up with targeted policies to contain air pollution.
By 2050, almost 68% of the world's population will be living in urban cities and breathing in these pollutants. Cities are at the forefront of air pollution impacts as well as interventions. With increasing awareness about air quality in countries and policies to keep air pollution in check, nations have the potential of reigning in this menace. However, with each passing year and skyrocketing air pollution rates, being able to breathe clean air still feels like a dream.