With just days to go before the start of the Beijing Olympics, China is stepping up efforts to control pollution.

China has promised to meet World Health Organization standards for the Games, but in recent weeks, pollution levels have at times been about double the benchmark Chinese officials had hoped to achieve.

Beijing, the host city of the 2008 Games, started an emergency anti-air-pollution campaign on July 20, temporarily closing factories and keeping about half the city's cars off the road on any given day. That effort was also expanded to the co-host city of Tianjin and Hebei province.

The government has gone so far as to shoot chemicals into the air, hoping to create rain to clear the smog. Despite their efforts, high temperatures, low winds and continuing high levels of emissions have created an ongoing problem with air quality.

So, Chinese officials have added a human touch to their anti-pollution efforts. They're also employing human sniffers, who have been deployed to areas around Olympic sites to find foul air.

"When somebody makes a complaint, we come out, and by first using our sense of smell we can tell whether there is a harmful substance," one engineer told CTV News through a translator.

There are machines that can do what the human sniffers do. They can even identify specific chemicals in the air. But human sniffers say no machine is as good as the human nose.

Sniffers can detect a bad smell in seconds, and scientists have proven that the human snout can distinguish between 10,000 different odours.

Becoming a nose detective means undergoing months of training to learn about a wide range of harmful chemicals. Human sniffers are used in several countries around the world, and China's human sniffing teams have successfully shut down several pollution violators in recent months.