Study shows Chennai’s air pollution far exceeds WHO standards

Greenpeace study reveals Chennai's air pollution levels exceed WHO guidelines, prompting need for stricter standards and improved monitoring.

As cities continue to grow, the complexity of managing air quality has increased, prompting the question if existing strategies and standards are enough to cope with the worsening air pollution crisis.

A recent Greenpeace study analysing air pollution trends in 2023 across 10 cities in South Indian States reveals that Chennai’s monthly average PM2.5 (fine particulate matter) levels are four to seven times higher, and PM10 (coarse particulate matter) levels are three to six times higher, compared to WHO annual guidelines.

Particulate matter consists of particles small enough to be inhaled, potentially leading to significant health issues. Particles smaller than 10 micrometres can penetrate deep into the lungs, and some may even enter the bloodstream. Among these, particles with a diameter of less than 2.5 micrometres, known as fine particles or PM2.5, represent the highest health risk.

The report titled ‘Spare the Air 2.0’ shows that compared to World Health Organization (WHO) guidelines, the annual average level of PM2.5 is six to seven times higher in six cities, including Chennai.

In Chennai, the monthly average trend indicated that PM2.5 levels are four to seven times higher, and PM10 levels are up to six times higher than WHO annual guidelines. 

Additionally, PM2.5 surpasses the National Ambient Air Quality Standard (NAAQS) annual limits in January, while PM10 exceeds these limits in January, February, October, and December.

The key takeaway from the study, however, is the significant disparity between WHO standards and the NAAQS. The annual average NAAQS standard for PM10 is 60 μg/m³, while the WHO standard is 15 μg/m³; for PM2.5, the NAAQS standard is 40 μg/m³, compared to the WHO standard of 5 μg/m³.