Talk about what human behaviors can cause air pollution.

Beijing was besieged by heavy fog again yesterday. The Municipal Meteorological Observatory issued the third foggy yellow warning after autumn, and Beijing's air quality dropped to level 5 heavy pollution for the first time in six months. "Workers Daily" quoted a retired worker who lives near Youth Lake in Dongcheng District of Beijing as saying, "Beijing will soon become a foggy city!"

According to the report, meteorologists said that the weather with excessive air quality in Beijing will last for 2 to 3 days, and it is expected that there will be 4 to 5 northerly winds on the 6 th, which is expected to alleviate the bad air pollution.

According to the analysis of experts from Beijing Environmental Protection Bureau, there are two main reasons why pollutants in Beijing are easy to condense:

First, because of the large amount of pollutants, "there are many pollution factors such as automobile exhaust, industrial pollution, dust from construction sites, and the composition of pollutants is also very complex, forming compound pollution, which is rare in the world and makes the atmospheric environment fragile." Not long ago, a shocking news came out: satellite images showed that Beijing's automobile exhaust pollution ranked first in the world.

The second is the influence of Beijing's topography. "Beijing's east, west and north are mountains, and only the south is the plain. Therefore, only when the north wind brought by cold air blows over and pollutants spread to the south can air quality be improved. If it is other wind directions, it will be blocked by mountains, and pollutants will still' nest' in the urban area. "