CHENNAI: There has been a significant spike in air pollution levels in Chennai over the past few days. On Wednesday morning, the city’s air quality index (AQI) touched 130, which, as per National Ambient Air Quality Standards stipulated by the Central Pollution Control Board, falls under the ‘moderately polluted’ category, enough to cause breathing discomfort to those with lung, asthma and heart diseases. The city’s AQI was near 100 last week, sources said. Gummidipoondi, near Chennai, made it to the list of top 10 polluted cities in India on three of seven days over the past week, sources said.
Chennai has seven continuous ambient air quality monitoring stations that provide real-time levels of different pollutants. Of the seven stations, one at Alandur bus depot has recorded AQI of 195, which is close to ‘poor’ category. Likewise, Perungudi also recorded a higher AQI of 164. The AQI in only two stations, Velachery and Royapuram, was below 100, categorised as ‘satisfactory’, sources said.
‘Condition may improve after weather systems in sea weaken’
The dominant and most harmful pollutant is PM 2.5, which peaked to 318 in some of the monitoring stations. The concentration of harmful particulate matter is several times higher than the prescribed limit. The World Health Organisation prescribes 25 ug/m3 as a safe limit, while India has fixed a standard of 60 ug/m3. Tamil Nadu Pollution Control Board officials attribute the spike in pollution levels to unfavourable meteorological conditions that are building the emission load.
The Met Office said the conditions would improve in two or three days after the weather systems in the sea weaken. PM 2.5 particles are 20 times smaller than the width of human hair. On inhaling them, the ultra-fine particles are quickly absorbed into the bloodstream, penetrating deep into the respiratory and circulatory systems.
Even short-term exposures to these particles can trigger symptoms of asthma and cause respiratory or heart issues, experts said. P Senthamarai Kannan, senior scientist at the Regional Meteorological Centre, told TNIE, “For the past few days, there is still-atmosphere. Also, the cold wind from the north has reduced the night temperature by a couple of degrees.
The sea breeze is also weak due to the weather system in the Bay of Bengal. All these factors hamper the dispersal of pollutants. The weather conditions would change in another 2-3 days and northeast monsoon rainfall that will start from October 29 would keep a check on pollution levels.” The rainfall in north Tamil Nadu was affected because of cyclonic storm ‘Hamoon”, which crossed Bangladesh coast on Wednesday and weakened into a deep depression.
The system would further weaken in the next few days. The pollution levels also went up in Gummidipoondi. But pollution in places like Ramanathupuram and Thoothukudi remained within safe limits thanks to the rainfall activity triggered by the weather system in the Arabian Sea. Sunil Dahiya, analyst, the Centre for Research on Energy and Clean Air (CREA), told TNIE, “Chennai region has a lot of industries, coal-based power plants, and a high number of vehicles.
All these lead to huge emissions and contribute to the worsening of air quality. While Chennai is a coastal city and air pollutants get diluted due to the high intermixing of air between sea and land, the city holds huge potential to reduce emission loads and can set an example by becoming the first city to move towards WHO daily guideline levels.”