Pollution reached dangerous levels this month in New Delhi and other parts of northern India, dropping sharply since October, when people breathed in the cleanest air of the four years.
These are some of the factors that cause sudden changes in air quality and exacerbate the problems often caused by burning crops and Diwali fireworks.
Why a relative drop in October?
In recent years, after farmers have finished harvesting rice, the air quality of the entire region began to decline gradually around October. Producers in Punjab and Haryana near New Delhi are beginning to expand their space for wheat, usually by burning the stubble of rice fields left by mechanized harvesters.
However, the heavy rain this year made it difficult for farmers to ignite and replant the stubble in the rice fields.
As a result, the air quality index, which measures the concentration of toxic PM2.5 particles in 1 cubic meter of air, averaged 72 across the region in October, well below 126 in the same month.
It still exceeds what the government says is a “safe” limit of 50.
Why a sudden spike in November?
Grain growers had to act swiftly to make up for the lost time in October.
On average, they would have taken 20 to 25 days to harvest rice and plant wheat. Speed is everything, as delayed planting can reduce yields and incur significant losses.
This year, we’ll focus on the first two weeks of November, and many say we’ll burn the entire area at once, rather than shifting the fields. Crop burning pollution peaks when temperatures cool further and pollutants are trapped in the air in dense winter fog and smog.
It was also in line with Diwali when the Indians lit coconut as part of an ancient Hindu tradition.
On Friday, the day after the festival, the air quality index in New Delhi and other cities rose to 451 on a scale of 500, indicating a “serious” condition.
Why is Delhi vulnerable to pollution?
The vast plains of northern India are drier and dustier than the rest of the country. Despite being one of India’s greenest cities, New Delhi is also exposed to pollutants from Afghanistan and Pakistan, experts say.
Dust from the Thar Desert, or the Great Indian Desert, in the northwestern part of the subcontinent contributes to Delhi’s pollution.
Outside the city, experts say that farmers are also slow to adopt technologies and technologies that can reduce the pollution caused by burning crops.
Since 2018, India has provided farmers with up to 80% subsidies and is buying machines that remove the stubble of rice left in the fields by mechanized pickers without burning.
However, poor implementation of the plan means that many farmers still prefer to burn crop waste.
