WHO report warns over 80 per cent of the world's city dwellers breathe poor quality air

A new report by World Health Organisation warns the increasing risk of life threatening diseases lurking in the most polluted cities of the world. It says over 80 per cent of the world's city dwellers breathe poor quality air, increasing their risk of lung cancer and other life-threatening diseases.

Urban residents in poor countries are by far the worst affected, it said. nearly every city (98 per cent) in low- and middle-income countries has air which fails to meet the UN body's standards, it added. "Urban air pollution continues to rise at an alarming rate, wreaking havoc on human health," Maria Neira, the head of WHO's department of public health and environment, said in a statement. (Also read. India's 41 tier-II cities face high air and water pollution; WHO Report)

The agency’s latest air pollution database reveals an overall deterioration of air in the cities and highlights the growing risk of serious health conditions also including stroke and asthma. For the report, data was collected from 795 cities in 67 countries between 2008 and 2013 and it focused more on outdoor rather than indoor air.

Prevalence of harmful pollutants like sulphate and black carbon was also tracked through which WHO found that air quality was generally improving in richer regions like Europe and North America, but worsening in developing regions, notably the Middle East and southeast Asia. (Also read. Now get real time information on air pollution levels via Twitter in 13 cities of India)

In a sample of selected mega-cities with a population above 14 million, New Delhi was the most polluted, followed by Cairo and Dhaka. Several factors determine the quality of air that a city breathes, major one is transportation. Other than that waste management, diesel generators and such chemical waste may also contribute to bad air quality.