The Environment Monitor Center of Yinchuan, Ningxia Hui Autonomous Region, recently launched a campaign to test in-car air quality for free. More than 50 cars have bid for the testing.

A total of 39 enrolled cars were inspected for formaldehyde and total volatile organic compound (TVOC) at the center on June 9. Before the test, the cars have to idle and remain stationary for more than 20 minutes.

On March 1, a guideline on evaluation of air quality inside passenger cars jointly issued by the Ministry of Environmental Protection and the China’s quality watchdog began to take effect, becoming China's first in-car air quality criteria.

According to the guideline, an eligible car should contain less than 0.1 mg formaldehyde per cubic meter and 0.6 mg TVOC per cubic meter. All of the tested cars are qualified in formaldehyde content, but 33 cars of them contain TVOC beyond the standard.

Yu Fusheng, a staff member with the center, said toxic gas inside cars mainly comes from in-car accessories and interior decorations.