The presence of heavy metals, including nickel, manganese and silica, in the ambient air has technically put Chennai in the ‘unhealthy’ category.
Air samples were collected in 20 locations across the city during February-March 2021.
Out of that, samples in 19 locations contained heavy metals, according to Health Energy Initiative (India).
“These heavy metals cause irreversible damage to human beings. And they are not confined to any particular geographical area but present in 19 of the locations that we sampled,” said Vishvaja Sambath, a city-based air pollution researcher.
From the samples analysed at a U.S. lab, it was found that the presence of silica, manganese and nickel were beyond the annual average level of exposure. Citizens living in the 19 locations, where levels of silica were high, are at risk of chronic lung problems. Manganese is a known neurotoxin that affects the neuro-behavioural functions and prolonged exposure can cause permanent brain damage.
Manganese exceeded safe limits in 12 sampling locations. Nickel, which is a potent carcinogen can also affect the respiratory and immune systems in the body.
The group has been conducting air pollution studies since 2017, except for 2020 due to the pandemic.
“We chose to take samples during different seasons and found that there was not much change in the parameters except for some places in north Chennai,” she said.
The study, which primarily studied PM 2.5 levels (particulate matter below 2.5 micron size), found that it exceeded the Indian 24-hour National Ambient Air Quality Standard (NAAQS) for PM 2.5 of 60 microgram/cubic metre by 1.1 to 3.8 times.
Locations sampled included neighbourhoods that are industrial, commercial and residential in nature. The results of the study indicate that there is a need to develop a local-level air quality monitoring and plan to control air pollution and protect public health.
Tirusulam (near airport), Parry’s corner and Vyasarpadi (near fishing harbour) had levels of PM 2.5 between 228 and 176 microgram/cubic metre, which is categorised as ‘very unhealthy’ by the U.S. EPA.
“People living around these sampling locations seem to have lost their right to clean air. Despite the pandemic, every single breath of polluted air taken by people in these regions has an added danger of lowering their lung capacity and eventually reducing their life expectancy. This can increase the hospital admissions, emergency visits and fatalities which can be identified only through a health assessment in the areas concerned,” said Gajapriya, an air pollution researcher with Healthy Energy Initiative (India).