Scientists push chemistry-driven policies to boost India's air quality

Mumbai, India—In Chandrapur, a city in central India of about 466,000 people, air pollution affects one of every three households. People develop respiratory diseases like asthma and bronchitis, skin allergies, eye allergies, and pneumonia, says Gopal Mundhada, a local physician who runs the Dr. Mundhada Bharati Hospital. He adds that the disease burden has increased steadily over the past few decades and blames the public health crisis on the severe pollution caused by the coal-fired Chandrapur Super Thermal Power Station (CSTPS), the largest station in the country (PDF).“You can see the smoke in the air, the layers of ash on rooftops and cars,” says Mundhada, who has been working in the region for more than 50 years. “The smoke, ash, and gases rising from the power plant—they circulate in the air, work as allergens.”The government-owned CSTPS emits large volumes of sulfur dioxide, two to eight times as much as the government’s own prescribed limits, even as a litigation against the power plant remains pending before India’s apex court. But the real threat lies not in what comes directly out of the smokestack but in what happens in the upper atmosphere afterward. The SO2 from the thermal plant reacts with ammonia in the atmosphere, forming ammonium sulfate, a major component of India’s pollution (PDF) from fine particulate matter 2.5 μm or less in diameter (PM2.5). Over half of India’s PM2.5 pollution is formed this way—when invisible precursor gases undergo chemical reactions in the atmosphere.—when invisible precursor gases undergo chemical reactions in the atmosphere.Particles—both PM2.5 and those