The Met office said the situation in Delhi this time is better than last year.
New Delhi: Delhi woke up on Friday morning to a thick, toxic haze after a night of fireworks to celebrate Diwali despite ban ordered on their sales by the Supreme Court. Air pollution was 18 times the healthy limit in some places and residents complained of eyes watering and aggravated coughs as levels of PM 2.5, tiny particulate matter that reaches deep into the lungs, rose alarmingly. The national capital ranks among the world's most polluted cities.
Here are 10 points on air pollution a day after Diwali:
An index of air quality or AQI was way above 300 on Friday and some parts of Delhi such as Mandir Marg showed an air quality reading of 941, close to the maximum level of 999 beyond which no readings are available. The index measures concentrations of PM 2.5, PM 10, ozone, nitrogen dioxide and sulphur dioxide among other indicators.
An AQI from 0-50 is considered good, 51-100 is satisfactory, 101-200 is moderate, 201-300 is poor, 301-400 is very poor, and 401 and above is severe. PM 2.5 and PM10 are micro particles suspended in the air that cause smog and haziness and make it difficult to breathe when levels are elevated. The permissible level of PM 2.5 is 60µg/m³ while PM10 is 100 µg/m³.
AQI of above 300 is "hazardous" the most severe level on a U.S. embassy scale of measurement. A hazardous level is an alert in which everyone may experience ill effects and are advised to stay indoors.
Air quality usually worsens in New Delhi ahead of Diwali, the festival of lights, and the Supreme Court had temporarily banned the sale of firecrackers, aiming to lessen the risk to health. But many still lit fireworks across the capital late into the night on Thursday, either using old stocks or buying them from neighbouring states.
Some environment activists said the court order was poorly enforced and firecrackers were still available. "Breathe nitrate and ammonia, home grown, hand made!" said environmentalist Vimlendu Jha in a Twitter post calling for city authorities to declare a public emergency.
Dipankar Saha, a scientist at the government's Central Pollution Control Board, said the still weather had also played a part in the toxic haze hanging over the city.
But pollution levels were better than at last year's Diwali when crop burning in nearby states and firecrackers combined. The Met office said favourable climate prevented smoke-filled air from the agricultural belt of Haryana and Punjab, where farmers are burning crop despite warnings, from entering Delhi.
Chennai, which reported a decrease in sale of crackers too choked under a cloud of smog this morning and Mumbai witnessed a dense haze.
A new study has said India has the most deaths caused by pollution in the world, with 2.5 million people dying early because of pollution in 2015. China was second with 1.8 million pollution-related deaths, according to The Lancet Commission on Pollution and Health, a two-year initiative seeking to highlight the issue.
In November last year, the Supreme Court had stopped the sale of fireworks within the National Capital Region based on a petition by three children aged between six years and 14 months raising an alarm about toxic pollution and diseases caused by it. Last month, the court temporarily suspended the ban and allowed the sale of crackers, saying a complete ban would be "extreme". Then days later, the court brought back the restrictions, saying it wanted to assess the impact of a cracker ban on Diwali.