Chennai's Foggy Mornings Lead to Dangerous Air Pollution Surge
Since Sunday, Chennai has experienced foggy and misty mornings, creating a picturesque yet hazardous start to the week. While these conditions offered a pleasant ambiance for morning walkers, they have trapped pollutants close to the ground, causing air quality to deteriorate significantly across the city.
Air Quality Index Reaches Alarming Levels
Over the past three days, several monitoring stations recorded air quality index (AQI) values soaring above 100 and 200 at 6 a.m., categorizing them as 'moderate' and 'poor'. By Tuesday evening, the situation worsened dramatically. Kodungaiyur's AQI breached 350, slipping into the 'very poor' category, indicating severe health risks for residents.
Data from Tuesday, February 10, highlights this spike. At 6 a.m., Kodungaiyur recorded an AQI of 276 (poor), while other areas like Arumbakkam (129), Manali (176), Perungudi (111), and Royapuram (145) remained in the 'moderate' range. However, by 7 p.m., Kodungaiyur deteriorated to 359 (very poor), and Manali and Royapuram climbed to 205 and 244, respectively, shifting from 'moderate' to 'poor'. This occurred despite wind speeds improving to 12-15 km/h, suggesting other factors at play.
Pollutant Analysis and Historical Trends
In areas with dump yards, such as Perungudi and Kodungaiyur, PM2.5 was the prominent pollutant, known for its ability to penetrate deep into the lungs. Other stations primarily recorded PM10, which includes larger particulate matter. Early morning air quality has declined compared to previous days. On February 9 at 6 a.m., AQI largely stayed in the 'moderate' category, with Kodungaiyur recording the highest at 122. Data for Manali and Velachery was insufficient that day.
The trend shows a gradual but steady worsening since Sunday. On February 8, dense fog blanketed much of the city, with Velachery recording 284 (poor), while Manali (173), Arumbakkam (132), and Kodungaiyur (112) were in the 'moderate' range.
Meteorological Factors and Expert Warnings
Meteorologists attribute the fog and mist to the interaction of northerly and north-north-easterly winds with moist easterlies from the Bay of Bengal. This led to condensation, causing pollutants to attach to water vapor and remain suspended near the surface instead of dispersing, exacerbated by calm wind conditions.
Emissions primarily stem from local sources, including vehicles, power plants, dump yards, waste burning, and construction. Pollution expert Sunil Dahiya expressed concern over worsening air quality despite favorable coastal winds. He stated, 'For coastal cities like Chennai and Mumbai, sea breezes usually disperse pollutants. If air quality continues to worsen despite good winds, it means emissions exceeded the city's carrying capacity. Chennai must act now.'
Forecast and Broader Implications
The India Meteorological Department (IMD) forecasts mist or haze to persist in isolated pockets over Chennai, Tiruvallur, Kancheepuram, and Chengalpet. Mahesh Palawat, chief meteorologist at Skymet Weather, indicated that early morning mist may last another two to three days. He added, 'Winters are nearing their end across the country. Temperatures may gradually rise, a trend already visible over parts of north India.'
This situation underscores the urgent need for environmental measures in Chennai to combat rising pollution levels, especially as weather patterns shift with the approaching end of winter.
