George Easow’s move to India to start a clinical diagnostics business lasted just three weeks before he was persuaded to return to Britain.

The persuading was done by his 7-month-old daughter, Fiona. Within days of moving to New Delhi, the child was wheezing and gasping for air because of smog. “She could hardly breathe,” her father said.

Fiona was kept indoors and put on medication. Nothing worked. “We had to make a call,” said Easow, a molecular biologist. He added that her symptoms disappeared once the family left, and they haven’t recurred.

For the 16.8 million residents of India’s capital, the wheezing continues. The bad news is that it’s going to get worse. And New Delhi isn’t alone: Cities across the nation suffer from some of the worst air quality in the world. As a result, the shortened life spans of productive members of the urban population are costing the country about $18 billion a year, according to a recent World Bank report.

While Beijing and Shanghai make headlines for air pollution caused by factory smokestacks burning coal, Delhi residents get their smog right in the face from cars and trucks running on cheap diesel. India subsidizes sales of the fuel to the equivalent of $15 billion a year, encouraging purchases of diesel vehicles that can pump out exhaust gases with 10 times the carcinogenic particles found in gasoline exhausts.

The result: Delhi’s air on average last year was laced with twice the toxic particles per cubic meter being reported in Beijing, leading to respiratory diseases, lung cancer and heart attacks.

“I have no doubt, 100 percent, that diesel exhaust is contributing to a rise in asthma, respiratory illnesses and hospitalizations,” said T.K. Joshi, director of the Centre for Occupational & Environmental Health in Delhi at Maulana Azad Medical College.

“Diesel exhaust is a carcinogen,” Joshi said in an interview last month, referencing a report by the World Health Organization in October.

Air particulate pollution causes more than 116,000 deaths annually in India, hitting the younger, most productive members of the population the hardest, according to Muthukumara S. Mani, senior environmental economist at the World Bank.

Diesel passenger vehicles accounted for 49 percent of all new cars sold in India last year, up from a third in 2008, according to the International Council on Clean Transportation.The number of new passenger vehicles sold each year may almost double to 5 million by 2020, and the share of diesel models is surging as the fuel sells at a 24 percent discount to gasoline. Besides being cheaper, diesel gets better mileage than gasoline, adding to the fuel’s economic attractiveness.

In India, diesel exhaust systems don’t come with equipment to remove potentially lethal emissions. One reason: Oil refineries produce diesel with levels of sulfur that would ruin the exhaust-scrubbing equipment required in other countries.

The automobile industry will have “no difficulty” installing exhaust technologies once India raises emission standards and fuel quality, the Society of Indian Automobile Manufacturers said in an e-mailed response to questions.

Diesel engines emit PM2.5, airborne particles and liquid droplets measuring less than 2.5 micrometers, or one-30th the width of a strand of hair. Because they’re so small, they penetrate deep into the lungs and pass into the bloodstream, according to the U.S. Environmental Protection Agency.

In October, the World Health Organization classified PM2.5 as a Group 1 carcinogen, similar to asbestos and tobacco, saying exposure can cause lung cancer, complicate births and increase the risk of bladder cancer. Short-term spikes can kill, triggering strokes, heart failure and asthma attacks, according to the American Lung Association.

In 2013, the annual average concentration of PM2.5 in New Delhi was 173 micrograms per cubic meter, compared with 89.5 micrograms in Beijing, according to data from India’s Central Pollution Control Board and the Beijing Municipal Environmental Monitoring Center. The threshold for average annual exposure as recommended by the WHO is 10 micrograms.

Didier Marti


New Delhi residents get their smog right in the face from cars and trucks running on cheap diesel.

: Smog paralyzes cities in northeast China: Thick, choking smog enveloped cities in northeast China for a second day Tuesday, snarling traffic and closing schools, airports and highways. In some places, visibility was reduced to a few yards.