Air pollution has been a severe public health problem in China recently, especially in January and February because of cold weather. Favorably, air pollution across China seemed to have substantially improved during the first two months of 2019.
This statement was made after checking the Real-Time Map of Air Pollution, hosted at the US-based nonprofit Berkeley Earth website, and comparing it visually with the air pollution patterns during the same period last year.
As shown in the following figure, air pollution across China during the first two months of 2019 demonstrated three features compared to comparable air pollution patterns in 2018.
First, PM2.5 concentration had been widely decreased across China during the past two months, as demonstrated on the representative screenshots of the Map with the color changed from purple or scarlet in 2018 to light red or yellow in 2019. In some areas, air quality was even frequently at a good level, as marked on the map by the color change to green.
Second, the area or range of severe air pollution patterns over the first two months of 2019 was notably reduced compared with the nationwide air pollution patterns in early 2018.
Finally, extreme air pollution episodes with PM2.5 concentration at unmeasurable levels, as shown on the real-time map for 8th February 2018, did not occur during the first two months of 2019.
With the evidence of recent improvement in air pollution in China, it may be important to explore possible reasons or underlying mechanisms. Two factors might have contributed to the improvement:
First, it may result from climate warming and reduced household energy consumption for heating and cooling. According to records, for example, the daily temperature in Beijing from 21st to 29th January 2019 (maximum: 5°-12°) was much higher than that during the same period in 2018 (maximum: -1°- -5°), as shown on the following graph.
Another factor may be related to the US-China trade war, which has resulted in China’s economic downturn. Since the summer of 2018, numerous manufacturers or enterprises have been shifting their production lines from China to other Asian countries, where labor costs are more affordable, to avoid US tariffs. Consequently, millions of Chinese workers have lost their jobs. As reported in the media, China’s economy grew at its slowest pace in almost three decades in 2018. Therefore, energy consumption for production might have been reduced, contributing to improving air pollution across China during the first two months of 2019.
The effect of the US-China trade war on air pollution across China may need to be further confirmed by quantitative evidence. A recent news report by the South China Morning Post suggests that the US-China trade war has no effect on the Chinese steel and aluminum sector, one of the major sources of air pollutants and CO2 emissions, which is being propped up by “surging domestic demand.” Since 2000, according to a report released by the Global Carbon Budget 2018, fossil CO2 emissions from China have increased from 3.35 to 9.84 billion tons (almost tripled). In 2017, fossil CO2 emissions from China covered 27% of global emissions (15% from the US and 7% from India). Usually, high CO2 levels may indicate high levels of other harmful air pollutants. If fossil CO2 emissions could not be reduced substantially, air pollution in China would remain a major concern.
