The United States' Environmental Protection Agency has teamed up with a Chinese environmental bureau to provide real-time air quality monitoring from the site of the World Expo in Shanghai.
EPA officials said Monday the move will help the city as it works with other areas in the region to clear its often thick blanket of smog.
The online system, dubbed AIRNow International, links technology developed by the EPA with the existing air quality monitoring network in Shanghai, a city of about 20 million.
Existing air quality monitoring systems in the region report day-before readings, which are little use in forecasting conditions for people whose health can be adversely affected by pollution.
"There's a real power in real-time data. Once you make data available hourly, you can forecast and people start paying attention," said Jeff Clark of the EPA's Office of Air Quality Planning and Standards.
"People start to buy into concern for air pollution," he said.
The EPA's AIRNow national index for reporting daily air quality was launched 11 years ago and provides information for nearly 400 U.S. cities.
The agency provided technical help to Shanghai's Environmental Protection Bureau. The two sides also are collaborating on reducing emissions from vehicles and power plants, and on climate change, water pollution and other environmental concerns.
Shanghai, China's commercial and industrial hub, staged a massive cleanup for the World Expo, which began May 1 and is expected to draw up to 70 million people. It razed old steel mills and shipyards to make way for the Expo along the banks of the Huangpu River and closed down heavily polluting factories, or moved them to distant suburbs.
The city also has sought to reduce car emissions by raising standards required of vehicles that travel into the city's center.
But cleaning up the city is only half the battle, since Shanghai lies downwind of heavily industrialized regions further inland. At times, farm fields in neighboring provinces are burned to clear stubble, leaving the city enveloped in a mucky haze.
"One key thing that has changed is the understanding that pollution is not a city-specific problem. They are reaching out to surrounding provinces to share data, similar to what we did in the United States," said EPA official Dale Evarts.
In Beijing, which struggled to clear its own smoggy skies for the 2008 Olympics, the U.S. Embassy has set up an air monitoring station that sends out hourly tweets on air quality in the capital.
Beijing's own official air monitors only measure relatively coarse particulate matter, PM 10. The U.S.-backed system monitors smaller, deadlier dust particles, PM 2.5.
The Expo-based monitoring system in Shanghai monitors PM10, sulfur dioxide and nitrogen dioxide.
On Monday, a cool but clear spring day, Shanghai's air conditions were reported as "good" and "excellent," following rains on Sunday.