Air pollution in China could be big business.
Two of the world's largest technology firms, IBM and Microsoft, are vying to tap the nascent, fast-growing market for forecasting air quality in the world's top carbon emitters.
Bouts of acrid smog enveloping Beijing prompted authorities in the Chinese capital to declare two unprecedented "red alerts" this month — a warning to the city's 22 million inhabitants that heavy pollution is expected for more than three days.