After a week’s respite from poor quality air, Mumbai's air quality deteriorated over the weekend. As temperatures remained relatively low, an overall air quality index (AQI) in Mumbai was measured at 310 on Sunday, which was in the 'very poor' category.
On Sunday, Mumbai’s overall air quality was only slightly behind Delhi’s air quality where an AQI of 339 was measured. Last Monday, Mumbai had recorded the cleanest air this year with an AQI of 156 (moderate). However, on Saturday, the AQI dropped to 320 and continued to remain 'very poor' on Sunday.
The AQI is a pollutant measuring indicator that is calculated by the System of Air Quality Weather Forecasting and Research (SAFAR) as the average of indices recorded across 10 locations in the city and the suburbs. SAFAR categorises AQI levels for PM2.5 in the 0-50 range as 'good'; 51-100 as 'satisfactory'; 101-200 as 'moderate'; 201-300 as 'poor'; 301-400 as 'very poor' and above 400 as 'severe'.
Six of the 10 locations measured an AQI that was in the 'very poor' category. Navi Mumbai recorded the worst air quality with an AQI of 374, closely followed by Andheri where an AQI of 340 was recorded.
“Owing to the presence of high pressure in western India, calm winds are prevailing in Mumbai and the surrounding regions. Additionally, regional contribution of winds in Mumbai is predominantly from oceanic air which is carrying pollution and dust from north-west India. This condition is leading to very poor AQI in Mumbai. With movement of high-pressure system to the west, the condition will be relaxed slightly which is going to improve the AQI to 'poor' for Mumbai in the next two days,” said a spokesperson from SAFAR.
Days and nights were pleasant in the city and the suburbs with temperatures remaining low. The minimum temperature at Santacruz station of the Indian Meteorological Department (IMD) was 17.4 degree Celsius, which was a degree above normal. At Colaba, the minimum temperature was 20 degrees Celsius, also a degree above normal.
Maximum temperature at Santacruz was recorded at 31.3 degrees, which was a degree above normal. At Colaba, the maximum temperature was 29.6 degrees Celsius, which was at par with normal.
KS Hosalikar, deputy director-general of western region, IMD, said, “From Monday, minimum temperatures are likely to fall in parts of north-central Maharashtra and Mumbai, Thane regions.”