This December 15, authorities in Delhi, India, moved school classes online and imposed a ban on construction works as a toxic haze enveloped the city, with air quality turning severe, causing flight and train delays.
According to the government's Safar app, Delhi’s air quality index (AQI) reached 471 in the early hours of the morning—around 30 times higher than the limit recommended by the World Health Organization. There are concerns that such extreme pollution levels may cause serious health problems, especially in young children and older populations.
From heavy air smog hanging over cities to poor air quality inside homes, people in densely populated areas are constantly exposed to dangerous air pollution. The statistics are scary. More than 99% of the global population is exposed to dangerous levels of air pollution. This exposure is not just unpleasant but also increases the chances of developing a number of serious illnesses.
Curious to discover the top 25 most polluted countries? Click through the following gallery.