Previously, it was reported that Chinese researchers installed a giant 100-meter high, the world’s largest, air purifier in one of the country’s provinces. Being able to reduce dust by 15% using minimal electricity – as it takes advantage of solar heat energy – this giant air filter would be desirable to be installed in the country’s capital, which encounters chronic air quality problem.
Just last Wednesday, Beijing’s air quality index (AQI) flew to hazardous level. Blue alert was called on Tuesday as sandstorm swept the capital and north of China. This was after an orange alert level was declared on Monday because of smog.
Ranging from the lowest to most severe level – blue, yellow, orange, and red respectively represent the Chinese alert system on air quality in terms of particulate density. With blue alert announced, residents were automatically advised to close doors and windows along with wearing of respiratory and eye protection; while an orange alert means manufacturing plants producing dusts must reduce their output by at least 30 percent.
Spanning an area of 1.5 million square kilometers, the dust and sand suspension blanketed Beijing, Tianjin, Hebei, Shanxi, Jilin, Liaoning, Heilongjiang, Inner Mongolia and Xinjiang.
An official AQI reading for Beijing reached 999 micrograms per cubic meter for PM10 particles and 238 micrograms per cubic meter for smaller particles categorized as PM25. At this level, air quality is classified as “hazardous”, in comparison with the limit established by World Health Organization, which indicates that more than 25 micrograms per cubic meter for PM2.5 level considered as unhealthy.
According to China’s National Meteorological Center (NMC), the sandstorm originated from the Inner Mongolia region and was subsequently blown eastward. This recurring phenomenon is linked to the yearly sandstorm in Mongolia’s Gobi desert, which pushed Beijing to build the Great Green Wall consisting of millions of trees planted along its border to prevent the sandstorms from passing through.
NMC also stated that this year, the sandstorm events in Northern China has decreased to four, coming from the average of 4.4 from the past decade.