Mild air pollution is expected to continue shrouding the capital for the next two days due to the weather, authorities said.

Low pressure and steady airflow will prevent the city’s pollution levels from decreasing. From 9 am Saturday to 9 am Sunday, the average density of PM 2.5 was 147 micrograms per cubic meter, almost twice the standard of 75 micrograms per cubic meter, according to the Beijing Municipal Environmental Monitoring Center.

Visibility on highways has also been poor.

via Mild air pollution to continue|China Scene|chinadaily.com.cn.

What does PM stand for?