CHENNAI: Chennai on Thursday surpassed Delhi hands down in air pollution under 'worrisome' smoggy conditions. At 9.30 am, Chennai Air Quality Index (AQI) was 264, while Delhi stood at 254.
Many areas in the Tamil Nadu capital recorded 'very poor' air quality. Velachery, Ramapuram, Manali, Kodungaiyur, Anna Nagar, Chennai Airport clocked pollution levels as high as 341, said Airveda.com
The realtime monitoring station of Central Pollution Control Board (CPCB) has consistently recorded AQI of 318, while Alandur and Velachery residential area registered 273. As per National Ambient Air
Quality Standard (NAAQS), AQI between 51-100 is considered satisfactory.
If you consider PM 2.5 concentration levels, all the stations witnessed a spike as high as 345 µg/m3 (micrograms per cubic meter). PM 2.5 is a tiny particulate matter of diameter 2.5 or less than 2.5
microns that can enter deep into the lungs. The National Ambient Air Quality (NAAQ) standard for PM 2.5 is 60 µg/m3.
Met officials said the current high pollution levels trend would continue till Saturday. The northeast monsoon showers are likely to resume from Sunday. Meteorologists said with high humidity and still
air, the pollutants just hang in the air unless the winds pick up speed.
N Puviarasan, director of Area Cyclone Warning Centre of Regional Meteorological Centre, said Chennai would experience dry weather for two more days, while rainfall activity would resume in southern districts from Friday. "The pollution levels will reduce from Saturday or Sunday as Cyclone Bulbul that formed in Bay of Bengal moving up north dragging all the polluted air," said weather blogger Pradeep John.
Experts feel there are not enough continuous ambient air quality monitoring stations in Chennai to make a correct estimation of pollution levels. According to urbanemission.com, which has conducted a case study on Chennai, the city requires at least 38 continuous air monitoring stations to statistically, spatially, and temporally, represent the mix of sources and range of pollution in the city (current status – 11 manual and 3 continuous).
The modeled source contributions highlight transport (including on road dust), industries (including the coal-fired power plants), and open waste burning as the key air pollution sources in the urban areas of Chennai.
Studies show the city benefits from the land-sea breeze, limiting the contribution of sources outside the urban airshed to an estimated 13% of the ambient annual PM2.5 pollution.