For the sixth day in a row, pollution levels in the city continued to increase, with the pollutant-measuring indicator — air quality index (AQI) — at 283, which falls under the ‘poor’ category.
Pollution in the city is expected to get worse on Sunday as an AQI of 286 (poor) was predicted by the System of Air Quality Weather Forecasting and Research (SAFAR).
From Monday onwards, the city saw a gradual rise in AQI levels at 216 (poor) to 257 (poor) on Thursday till 283 (poor) on Saturday. Locations such as Malad, Andheri, Bandra Kurla Complex and Navi Mumbai were the most polluted on all days.
An AQI between 201 and 300 is considered poor, that between 301 and 400, ‘very poor’, which means people with heart or lung disease, older adults and children should reduce prolonged or heavy exertion.
SAFAR researchers said over the past week, the concentration of pollutants during the day has been higher than that during the night. “Weather factors such as low wind speed and below-normal night temperatures have led to an increase in pollution during the night, which gets partially dispersed during the day due to solar radiation and comparatively higher wind speed,” said Neha S Parkhi, senior programme officer, SAFAR. “We expect weather conditions to be similar next week. ‘Poor’ pollution levels are likely to persist.”
Parkhi said citizens should avoid heavy exertion from evening onwards. “The boundary pollution layer is closer to the earth’s surface and can cause issues for people with existing lung ailments,” said Parkhi.
On Saturday, five of 10 locations in Mumbai recorded ‘very poor’ AQI levels, four locations falling under the ‘poor’ category and only one location observed ‘moderate’ air quality.
Malad was the most polluted, and recorded its worst air quality for the season at 325 (very poor), followed by Navi Mumbai at 314 (very poor) with Andheri and Bandra Kurla Complex close behind at 308 (very poor) each. On the other hand, Borivli recorded the cleanest air at 183 (moderate).
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With a large difference between the day and night temperatures in Mumbai over the past few days, officials from the weather bureau said it could lead to health issues.
On Saturday, night temperature in the suburbs was 17 degrees Celsius, 4.5 degree Celsius below normal, recorded at 5.30am. In comparison, the day temperature at the Santacruz weather station, representative of the suburbs, was 34.5 degrees Celsius, a degree Celsius above normal. This means the difference between the night and day temperatures was a little more than double.
Similarly, south Mumbai recorded the minimum and maximum temperatures at 21.8 degrees Celsius (1.5 degree Celsius below normal) and 34.2 degrees Celsius (0.7 degree Celsius above normal), a difference of 12.4 degrees Celsius.
Officials from the weather bureau said weather factors such as a shift in wind patterns and humidity levels play a major role in the difference between temperatures. “During the day, the city has been observing easterly winds that are warm along with a high humidity (rise in moisture) levels. However, by the evening, wind patterns are shifting to northerly, which means cold winds from the north with a drop in humidity levels from 6pm onwards,” said Shubhangi Bhute, director, Regional Meteorological Centre, India Meteorological Department (IMD).
She added that this was leading to viral diseases such as cough, cold and fever. “We expect this condition to subside over the next week as easterly winds are expected to prevail over the city both during the day and night,” said Bhute.
Moisture levels across the city varied on Saturday. Colaba recorded 80% humidity while only 39% was recorded at Santacruz.