Pollution in Beijing

Chinese workers clean stains on the ground under Tiananmen Gate near Tiananmen Square in a hazy day, Beijing, China. Beijing is facing a challenge to maintain air quality during the Olympic Games.

Chinese tourists stand on Tiananmen Gate near Tiananmen Square in a hazy day, Beijing, China.

A traffic police officer watches motorists at a city highway near the Olympic Green in Beijing. State media reports that Beijing may remove more cars from the roads and shut down additional factories as part of emergency measures if air quality worsens during the Olympics Games. Beijing authorities are likely to announce special measures soon, the official English-language China Daily reported on Monday.

The National Aquatics Center, also known as the Water Cube is seen hazy due to poor air quality in Beijing.

The hazy sight of the National Olympic Stadium, also known as the Bird's Nest, in Beijing, China. The stadium will host the opening and closing ceremonies and athletics competition for the games, which open on August 8.

The hazy and poor sight of the National Olympic Stadium, also known as the Bird's Nest, in Beijing, China. The stadium will host the opening and closing ceremonies and athletics competition for the games, which open on August 8.

Olympic volunteers stand outside the National Olympic Stadium, also known as the Bird's Nest, in Beijing, China. The stadium will host the opening and closing ceremonies and athletics competition for the games, which open on August 8.

Roads outside the National Olympic Stadium, also known as the Bird's Nest are seen before the inaugration of Olympics. Beijing could pull more cars from the roads and shut down additional factories as part of contingency measures if air quality worsens during the Olympic Games, state media has reported.