We all have stories about varying aspects of cardiovascular disease: blocked arteries, heart attacks, open-heart and bypass surgery, strokes and more. How it struck down the software engineer in his 20s, the middle manager in his 30s, the sparing eater, physically fit morning walker in his 40s.

There are some common threads of explanation for the explosion in cardiovascular disease across India.

One, the Indian is genetically predisposed to diabetes and other medical risk factors.

Two, the urban Indian—and, increasingly, the rural Indian—is given to a sedentary life (even if we did want to be active, our crummy urban infrastructure does not allow it) and unhealthy eating.

Three, we work too much and get too stressed.

By now, most Indians know enough to correlate these three factors with their cardiovascular experiences and stories. But there is a fourth factor that we rarely discuss, although it could well be the cause of the most puzzling cases, such as the sparing eater, physically fit morning walker in his 40s.

I refer to air pollution, the elephant in the room that patients and doctors often do not consider. It could be because the pollutant most firmly implicated in cardiovascular disease (and a host of other afflictions, such as respiratory and liver ailments) is invisible; and studies correlating its rise with the damage it does are hard to find in India. It could also be that air pollution is ubiquitous and just one of so many pollutants we live with.

PM2.5 is its name, particulate matter smaller than 2.5 micrometres. That is infinitesimally small, some 100 times finer than a human hair (or one ten-thousandth of an inch in diameter), a size that allows these particles to reach deep into the blood or the lungs, spurring respiratory and heart disease. Produced by factory smokestacks, dust and car engines—even the CNG engines we thought safe—PM2.5 particles are now regarded as the definitive indicator of urban air pollution.

A new study, released this week, confirms the link between PM2.5 particles and—not to put too fine a point to it—death. Published in Environmental Health Perspectives, an international journal, the study, led by scientists from New York University, is one of the largest ever in the US.

Surveying about half a million Americans, the study said that a minute increase in the concentration of PM2.5 particles can substantially increase the risk of death from all causes. It does not matter if you are a non-smoker. In any case, breathing the air in our cities is, often, equivalent to smoking many cigarettes a day.

For non-smokers, the risk of death from respiratory disease rises 27% for a 10 microgram increase in PM2.5 concentration in a cubic metre of air. The increase in risk of death from cardiovascular diseases is 10% and from all causes by 3%, the study found.

“Our data add to a growing body of evidence that particulate matter is really harmful to health, increasing overall mortality, mostly deaths from cardiovascular disease, as well as deaths from respiratory disease in nonsmokers," lead study investigator and health epidemiologist George Thurston is quoted as saying on EurekaAlert, the website of the American Association for the Advancement of Sciences.

If such a study were to be conducted in India, these risks are likely to be far greater. But we may still not do more than shrug. It registers only mildly with us that Delhi is one of the world’s most polluted cities and 13 Indian cities are in the list of the 20 worst globally.

Local governments do not react to steadily grimmer air-pollution developments, and a new air-quality index is all but ignored. While Bejing, sometimes, declares air-pollution emergencies, Delhi, with air that is, usually, far worse, barely stirs.

As I write this, the website of the national air-quality index—launched by the prime minister six months ago—refuses to open.

So, I turn to the only other easily accessible monitoring station—at the US embassy in Delhi. It shows that the PM2.5 concentration is 73.2 micrograms per cubic metre.

By Delhi standards, that is not so bad; the World Health Organization recorded an annual average double that figure. But the US embassy says Delhi’s air is “unhealthy".

This is the related health-effects statement: “Increased aggravation of heart or lung disease and premature mortality in persons with cardiopulmonary disease and the elderly; increased respiratory effects in general population."

The accompanying advisory says people with heart or lung disease, older adults and children should avoid “prolonged or heavy exertion", which everyone else should reduce anyway.

Delhi—stirred, somewhat, by an ongoing dengue outbreak and callous hospitals that turned away children, who later died—could not care less about PM2.5. Panicky people, these Americans.

Samar Halarnkar is editor of IndiaSpend.org, a data-driven, public-interest journalism, non-profit organization. He also writes the column Our Daily Bread in Mint Lounge.

Comments are welcome at frontiermail@livemint.com. To read Samar Halarnkar’s previous columns, go to www.livemint.com/frontiermail-

Close