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Searing Heatwave Leads to Deadly Ozone Pollution in Delhi


Scientists inform that ozone is a powerful oxidiser, which means it can damage cells in a process akin to rusting. Children and the elderly are at special risk. International studies have also found a strong association between ozone and daily premature death counts; deaths related to ozone exposure are more likely among people with pre-existing diseases.

Ozone that gets created in the polluted environment of a city can drift, depending on the wind direction, and move towards cleaner environs in the rural periphery. Here, it can begin to accumulate as it has less chances of reacting with other pollutants. It builds up faster at the outskirts of cities and can damage crops.

What do other governments do?

Ozone is included in the daily smog and health alert programmes in countries such as Mexico, the US and China. In Mexico City, the elderly, children and those suffering from respiratory and cardiac problems are advised to stay indoors when levels of ozone go up. The US-based National Research Council, part of the National Academies of Science, has recommended that local health authorities should keep the harmful effects of ozone in mind when advising people to stay indoors on polluted days. A study carried out in the US by scientists led by the University of Southern California and reported in Lancet has found that in high-ozone areas, the relative risk of developing asthma in children playing three or more sports was more compared to children playing no sports. Outdoor heavy exercise is not recommended as with every breath, athletes particularly take in 10 to 20 times as much air, and thus pollutants, as sedentary people do.

What should Delhi do?

“Delhi needs to act immediately to protect public health,” says Roychowdhury. “Explosive increase in vehicle numbers, especially diesel vehicles that spew much higher levels of NOx and volatile organic compounds, can only worsen the deadly recipe needed for formation of ozone in the city with hot and extreme climate.”

  • The city government must prevent this trend by making serious efforts to control NOx and volatile organic compounds that largely come from vehicles. Reduce numbers of vehicles, especially diesel vehicles. For instance, diesel cars emit three times more NOx than petrol cars and NOx is the main catalyst that triggers reaction among gases to form ozone.
  • The city government must introduce a daily health alert system to inform the sensitive population (children, elderly and those suffering from respiratory and cardiac problems) about the high daily levels and enforce emergency pollution control measures such as reducing traffic volume, allowing only clean fuel vehicles, and scaling up public transport, walking and cycling in the city.

Click here to read/download more details of the Analysis – “Heatwave Leads to Deadly Ozone Pollution in Delhi: CSE Analysis”.


Source: CSE.

The Centre for Science and Environment (CSE) is a public interest research and advocacy organisation based in New Delhi, India. CSE researches into, lobbies for and communicates the urgency of development that is both sustainable and equitable.