China is the world's largest consumer of coal , and this has fueled its economic growth and propelled it to become the world's leading economy . However, this incredible development comes at a high cost: its air pollution levels are alarmingly high. Citizens are forced to wear masks when going outside due to the toxic air, and authorities are compelled to take drastic measures such as closing airports and highways to prevent accidents caused by the reduced visibility resulting from smog.
This problem is not new . The most affected cities, such as Beijing and Tianjin, have been suffering from this phenomenon every winter for years, when coal use for heating increases and pollution becomes more concentrated in the air due to adverse weather conditions.
Why so much pollution?
The severity of pollution in China depends on several meteorological factors. Sunny, windy, or rainy days help disperse PM2.5 particles and other pollutants. However, on cloudy or windless days, a phenomenon known as temperature inversion occurs : warm air rises rapidly, leaving cold, dense air at the surface, where it traps pollution and keeps it close to the ground, worsening the situation.
When temperature inversions combine with fog, as has happened several times in Tianjin and other cities , pollution becomes even more dangerous. This not only affects the health of citizens but also leads to the shutdown of infrastructure such as airports and highways due to low visibility. A recent example was the closure of Nanyuan Airport in Beijing for several hours due to dense fog and pollution.
During periods of high PM2.5 concentration (particles with a diameter of less than 2.5 micrometers), it is recommended to stay indoors. These particles are so small that they can enter the lungs and bloodstream, causing serious health problems such as respiratory and cardiovascular diseases.
PM2.5 levels in China have exceeded 1.000 micrograms per cubic meter on some days, far surpassing the World Health Organization's (WHO) recommended limit of just 25 micrograms per cubic meter for safe exposure. These extreme conditions have led to partial shutdowns in cities, such as Jiangsu , where almost all highways were closed due to poor visibility, and Qingdao, where more than 50 flights were canceled.
Measures against pollution
Chinese authorities have had to implement drastic measures to reduce pollution levels. Beijing, Tianjin, and twenty other cities have been placed on red alert , the highest level of China's weather warning system. Thousands of factories have been closed, classes suspended, and traffic restricted on critical days.
Tianjin has been one of the worst-affected cities. On days of high pollution, airports have even been closed and dozens of flights canceled, as happened recently at Jinan airport , where more than 155 flights were affected by delays, cancellations, and diversions due to the dense smog.
Another worrying example occurred in Shandong and other affected regions where kindergartens and schools have been closed due to low visibility and extreme pollution, and the population has been asked to restrict outdoor activities as much as possible.
Contamination limits according to WHO
As mentioned earlier, the World Health Organization (WHO) considers that exposure to pollution levels above 25 micrograms of PM2.5 per cubic meter over 24 hours can cause serious health problems. However, Chinese cities like Beijing have exceeded that limit by up to 40 times , with levels exceeding 1.000 micrograms per cubic meter on critical days. Under these conditions, it is recommended to stay indoors, close doors and windows, and avoid any outdoor activity.
The situation in China illustrates the urgent need to reduce emissions of air pollutants to protect both human health and the environment. It is clear that as long as the economy continues to rely on coal as its main source of energy, episodes of extreme pollution will recur year after year.