北京居民对雾霾的反应

The city's office for severe air pollution emergency response said in a statement that the density of PM2.5, particles smaller than 2.5 microns in diameter, which have been a major contributor to the smog, climbed again on the night of Feb 23 and have remained at high levels.

The agency advised children and the elderly to stay indoors and to wear masks when going out. It also urged residents to take public transport and reduce driving. The agency urged middle schools, primary schools and kindergartens to reduce outdoor activities.

Xiao Xia is a Beijing resident who says the smog has caused her to experience unpleasant physical reactions.

"I have a really sore throat and my face hurts. I wear mask. It makes me feel comfortable."

Last Friday, the Beijing municipal government ordered 36 companies to halt production and another 75 to reduce production as part of a response mechanism when the pollution alert was raised to orange from yellow.

Beijing issued a yellow pollution alert on Thursday, the first since last October, when the emergency response system was put into place.

The city has a four-tier alert system, with blue, yellow, orange and red indicating the air pollution level in order of increasing severity.

A red alert indicates the most serious air pollution for three consecutive days. An orange alert indicates heavy to serious air pollution alternately for three consecutive days. A yellow alert indicates severe pollution for one day or heavy pollution for three consecutive days.

A red alert requires traffic to be cut with alternate driving days for even-and odd-numbered license plates, and schools to be suspended. Industrial plants are closed or told to reduce production when an orange alert is issued.

Bai Changqing is the director of the respiratory department of PLA 307 Hospital. He suggests that people choose appropriate masks based on their own needs.

"The N 95 mask is mask for medical purposes. This kind of mask can filter more than 90 percent of the PM 2.5 particles, but this mask is for professional use. Not everyone needs it, for the filter whole is very small. It may restrain people's ability to breathe to some extent. So people need to make choices based on their own needs."

According to Beijing Meteorological Administration a cold front is forecast to ease or disperse the smog on Wednesday evening.

For CRI, I am Li Dong.