BEIJING, Feb. 21 -- Chinese cities of Beijing, Tianjin and those in the surrounding areas are experiencing another round of heavy smog and pollution that is expected to persist for a week.

China Meteorological Administration (CMA) and the Ministry of Environmental Protection late on Thursday jointly issued an alert for pollution, forecasting severe conditions in northern Beijing, western Tianjin, central and southern Hebei province, as well as some areas in the west parts of Shandong province.

On Thursday morning, PM 2.5 readings in those regions exceeded 115 micrograms per cubic meter, far above the 25 micrograms level considered safe by the World Health Organization.

The CMA expects the smog to last for a week as no cold front is in sight to help disperse it.

PM2.5, airborne particles smaller than 2.5 microns in diameter, is a key indicator of air quality. Beijing's average PM2.5 index came in at 89.5 micrograms per cubic meter in 2013.

After experiencing frequent bouts of smog, the Chinese public has become increasingly sensitive to the health hazard.

To address public concerns, the government aims to cut the density of inhalable particulate matter by at least 10 percent in major cities by 2017.

In a meeting earlier this month, the State Council, the cabinet, named the reduction of PM2.5 and other pollutants in smoggy cities as the key task in the fight against air pollution.