Delhi and Kolkata report high pollution around Diwali

Air pollution remained high in Delhi and Kolkata around Diwali, with readings varying by date, monitoring system and averaging period. The Central Pollution Control Board (CPCB) reported Delhi’s air quality index (AQI) at 299 on November 10, the highest among six cities in its comparison. Kolkata readings ranged sharply overnight, including an average AQI of 437 at 2 a.m. under the West Bengal Pollution Control Board’s classification.

Delhi’s November 10 figure was based on the 24 hours ending at 10:30 a.m. UTC and used data from 58 of the city’s 59 monitoring stations. CPCB classified 299 as poor, a range in which prolonged exposure may cause breathing discomfort. PM10 and PM2.5 were listed as the city’s prominent pollutants.

The reading followed higher Delhi figures in the preceding days. CPCB daily readings cited for November 8 put the city’s AQI at 376, compared with 162 in Kolkata, 138 in Chennai and 132 in Mumbai. A separate CPCB bulletin at 4 p.m. on Monday, November 9, gave Delhi a 24-hour average of 344, ranking it tenth among the listed cities. Bahadurgarh, Haryana, topped that list at 400.

Kolkata’s figures came from different monitoring systems and observation times....