SUSHMITA PATHAK
LUTYENS’ DELHI IS one of the most iconic neighborhoods of India’s capital. Home to the country’s parliament, numerous embassies, and a lush, 90-acre Mughal-era park, it’s an architectural paradise, connected by tree-lined streets and roundabouts with mini-gardens. Yet despite being one of the city’s most refined districts, this clean, green neighborhood is home to something sinister. It is a hot spot for a dangerous and overlooked air pollutant: ozone.
India is no stranger to pollution, with many of its cities reporting some of the worst air quality in the world. Every winter, New Delhi gets shrouded in smog for days. But discussions about air pollution and policies to mitigate it mostly focus on particulate matter: PM2.5 and PM10—small particles or droplets that are only a few microns in diameter. However, scientists are increasingly raising the alarm about surface ozone. It’s a secondary pollutant that isn’t released from any source, forming naturally when oxides of nitrogen and volatile organic compounds—such as benzene, which is found in gasoline, or methane—react under high heat and sunlight. This makes ozone a particularly ugly modern threat—a problem that arises where pollution and climate change coincide.
“Even an hour of exposure can give you very poor health outcomes,” says Avikal Somvanshi, a researcher at the Center for Science and Environment in New Delhi. While ozone is beneficial in the high atmosphere, where it absorbs ultraviolet radiation, down on Earth’s surface, concentrations of it can be deadly. Data on its impacts is patchy, but a 2022 study estimates that ozone killed more than 400,000 people worldwide in 2019, up 46 percent since 2000. And according to the State of Global Air Report 2020, it is in India where the number of ozone deaths has increased the most over the past decade.
Ozone wreaks havoc in the respiratory tract. The gas can “inflame and damage airways” and “aggravate lung diseases like asthma,” warns the US Environmental Protection Agency. It does this by affecting the cilia, the microscopic hair-like structures that line the airways to help protect them, explains Karthik Balajee, a clinician and community medicine specialist based in Karaikal, India. After exposure “we are more prone to respiratory infections,” he says, adding that inhaling ozone also affects lung capacity. Studies show that long-term exposure is associated with an increased risk of chronic obstructive pulmonary disease, a lung disease that makes it hard to breathe, and increases the risk of dying from other cardiovascular or respiratory conditions. Even short-term exposure can land you in the emergency room. “One or two days following a peak in ozone, there have been increases in hospital admissions due to respiratory problems,” says Balajee.