Residents of Chennai have finally received a breath of fresher air, thanks to a welcome change in weather patterns over the past few days. Strengthening winds and light rainfall have contributed to a noticeable improvement in the city's air quality, pulling several key monitoring stations out of the 'poor' category and into 'moderate' levels.
Significant Drop in AQI Readings Across Key Localities
Data recorded on Saturday morning revealed a positive shift. At 10 am, the Air Quality Index (AQI) at stations in interior localities like Kodungaiyur, Perungudi, and Arumbakkam fell below the 200 mark, officially placing them in the 'moderate' category. This stands in stark contrast to the situation just a week prior, on December 20, when these same areas were grappling with 'poor' air quality as AQI levels had crossed the 200 threshold.
The specific improvements were substantial. Kodungaiyur's AQI dropped from 268 to 178, Perungudi saw a fall from 216 to 112, and Arumbakkam improved from 235 to 142. This positive trend was not limited to the morning hours; similar improvements were observed during the evening as well. Other stations, including Manali, Manali Village, and Velachery, have consistently remained in the 'moderate' category for over two weeks. Notably, Royapuram recorded a 'satisfactory' AQI of 63, though this can still cause minor breathing discomfort for sensitive individuals.
Meteorological Factors Behind the Cleaner Air
Experts have pinpointed the primary reason for this respite: strengthening northeasterly winds. Wind speeds, which had plummeted to a near-stagnant 3 kmph on December 20, picked up significantly to around 20 kmph by Saturday. This increased airflow is crucial as it helps disperse and dilute the concentration of pollutants hanging over the city.
There is more good news on the horizon. Chief meteorologist Mahesh Palawat from Skymet Weather indicated that light to moderate rainfall is likely across most parts of Tamil Nadu, including Chennai, between December 29 and 31. This expected rainfall is due to the strengthening northeasterlies increasing moisture incursion and has the potential to wash away pollutants, leading to a further reduction in pollution levels.
Health Implications and Pollutant Sources
While the shift to 'moderate' air quality is a definite improvement, health experts caution that it is still not considered healthy for prolonged exposure. People with pre-existing conditions like lung disease, asthma, and heart conditions may still experience breathing discomfort. The dominant pollutant at most stations on Saturday was PM2.5—fine, inhalable particles that pose significant health risks.
These PM2.5 particles originate from multiple sources common to urban environments, including:
- Vehicle emissions
- Burning of waste
- Construction and demolition activity
- Burning of wood
- Household cooking fuels
- Secondary aerosols formed in the atmosphere
Looking at the immediate forecast for Sunday, the city and its suburbs may experience mist or haze during the early morning hours. Partly cloudy skies are expected to keep the maximum temperature around 29–30°C and the minimum near 20–21°C. The coming days will be critical in determining whether the current improvement can be sustained and enhanced by the predicted rainfall.
