Air pollution in New Delhi surged to near-emergency levels on Monday, the first day of 2018. The Air Quality Index for Particulate Matter 2.5 – the concentration of the particulate matter of diameter less than 2.5 microns – was 431 at 9 pm, which the Central Pollution Control Board categorises under the “severe” pollution category.

The Air Quality Index for Particulate Matter 10 stood at 494 at 8 pm, also in the “severe” pollution category. PTI reported that people burst firecrackers in the national Capital on December 31 to welcome the new year, contributing to the rise in pollution.

An Air Quality Index reading up to 50 is considered “good” and up to 100 is considered “satisfactory”. A reading between 401 and 500 is ranked “severe” on the index, which means the air is dangerously filled with pollutants.

The Centre-notified Graded Response Action Plan, or GRAP, directs that construction activities in Delhi be banned and the odd-even vehicle scheme introduced when the PM 2.5 and PM 10 readings rise above 300 and 500 for a period of 48 hours. These measures were in place for a week in November when Delhi experienced alarming levels of pollution.

Mumbai’s air quality also falls

The air quality in Mumbai also fell on New Year’s Day, with the Air Quality Index for PM 2.5 at 281 at 10 am, in the “very unhealthy” category. However, this declined to 179 at 9 pm. The city’s air quality has been steadily dipping since the last week of December.