Air Pollution Quality Index

Air pollution in major cities across India reached alarming levels in the past week, particularly in Delhi where residents face a public health emergency. The national capital region has been shrouded in a thick blanket of smog, forcing most people to stay indoors. Flight operations at the Delhi airport were also affected due to the low visibility caused by the air pollution.

The Air Quality Index in Delhi dropped to 999 over the weekend, making it the most polluted capital city in the world. While the safe limit set by the World Health Organisation is 25, anything above 500 poses a serious risk to the respiratory systems of the general population.

Air Quality Index or AQI measures the concentration of PM 2.5 levels -- fine particles of less than 2.5 microns that can enter the bloodstream and penetrate the lungs and heart - which are linked to chronic respiratory diseases.

Not only does the toxic air affect healthy lungs, it is also found to cause premature deaths among those suffering from respiratory illnesses. According to Greenpeace, more than 1.2 million Indians died prematurely in 2017 due to air pollution.

One of the major reasons for the Delhi's toxic air is believed to be the burning of farm waste in neighbouring Punjab and Haryana. Delhi government officials have called the city a "gas chamber" and blamed the state governments of Punjab and Haryana of not doing enough to curb the illegal farm fires.

A significant drop in AQI levels was seen post-Diwali where fireworks played an overwhelming role in creating a toxic cocktail. Other cities where pollution levels have matched up to Delhi's are Lucknow, Patna and Kolkata.

While many social media users likened the air pollution in India to smoking cigarettes, some users shared screenshots of a real-time air quality index which showed the pollution level in the number cigarettes smoked.