People’s Daily reported that, on October 5, Beijing’s air pollution level peaked out in the morning with PM2.5 readings in a number of different locations reaching as high as 240. The Beijing Municipal Environmental Monitoring Center has been monitoring PM2.5 levels continuously and has strongly suggested that Beijing residents stay indoors, especially children, the elderly, and people with heart or lung disease. On October 6, the pollution intensified. In some areas the PM2.5 24-hour average number reached 435.
PM2.5 particles are air pollutants with a diameter of 2.5 micrometers or less, small enough to invade even the smallest airways. These particles generally come from activities that burn fossil fuels, such as traffic, smelting, and metal processing. The World Health Organization (WHO) considers a PM2.5 number below 10 to be safe. The highest PM2.5 level in Beijing was recorded by the U.S. Embassy on December 4, 2011. That number was 522. China started official monitoring not long after that. New York’s PM2.5 peak level was 68 on October 5, 2013.
[Editor’s note: According to a U.S. Embassy site in Beijing (http://beijing.usembassy-china.org.cn/aqirecent3.html), a reading of 201 to 300 is considered unhealthy; 301-500 is considered hazardous.]
Source: People’s Daily, October 5 & 6, 2013