The Guangdong Provincial Environmental Protection Bureau said Tuesday they were considering limiting the types of vehicles on Guangzhou roads to cut air pollution.

Guangzhou's air quality failed to meet the national standard for the first time last year, the Southern Metropolitan News reported Wednesday.

The content of dioxide sulfur in Guangzhou's air was 0.077 milligrams per cubic meter last year, exceeding the national standard of 0.06 milligrams. Authorities blamed coal-burning power plants for excessive dioxin sulfur levels.

The air content of dioxide nitrogen was 0.073 milligrams per cubic meter, close to the national standard of 0.08 milligrams with vehicle exhaust one reason listed for increasing dioxide nitrogen content.

The provincial environmental bureau was considering an air pollution alert system and other measures to prevent certain types of vehicles with heavy exhaust from driving on the road, said Chen Guangrong, vice director general of the provincial environmental bureau.

The department said it was impossible to prohibit people from buying vehicles, but the department could reduce exhaust fumes by adding cleaning agents to fuels.

Meanwhile, vehicles are not allowed to drive in the Baiyun Mountain area beginning Tuesday from 6 a.m. to 5 p.m.

Vehicles could still drive around the section from the mountain's west entrance to Mingzhulou, the Guangzhou Daily reported.

The mountain's management department said it was building a parking lot near the west entrance and the section would be included in the ban once the parking lot was finished.

The department said it had issued some permits to vehicles with special needs like those of the public security department and work units that had offices in the mountain area.

Hikers on the mountain said they breathed better air than usual after the vehicle ban Tuesday.