Recent news reports have proclaimed a dramatic reduction in China’s air pollution along with the coronavirus lockdown, yet data shows Beijing has actually seen pollution levels rise during this period. The headlines are based on images from NASA, finding that air pollution dropped 10-30% compared to the same period in 2019.
NO2 Pollution Levels Down 10-30% Compared the Same Period Last Year
Smart Air analyzed data from the Beijing Environmental Protection Bureau, comparing 6 different pollutants for the period 2019 to 2020. In contrast, the NASA study looks only at NO2 (nitrogen dioxide). NASA estimated that NO2 fell 10-30% across the whole of China during January and February, when compared to 2019.
This fits with results from our analysis. Beijing’s NO2 fell 21% compared to the same period in 2019.
Beijing PM2.5 Up 17% Despite Coronavirus Lockdown
However, NO2 is only one type of air pollution. According to the World Health Organization, particulate pollution “affects more people than any other pollutant.” For that sort of pollution, Smart Air analysis finds that PM2.5 has actually increased 17% during January and February, compared with the same period in 2019.
So why, even with Beijing under lockdown, has PM2.5 worsened over the prior year? With less traffic on the roads – up to 77% fewer trucks and 36% fewer buses in some cases – and hundreds of factories closed, it is reasonable to expect pollution to decrease.
Heavy industry surrounding Beijing is up and running
The area surrounding Beijing is China’s biggest steel manufacturing hub.
What’s more, these heavy industry factories are typically state-owned enterprises that have remained open despite the coronavirus lockdown. For example, a map of Beijing’s factory activity from 2nd March, 2020 shows almost all factories back online, except for a few (gray) points on the map.
However, some factories have closed due to the coronavirus. Why, then, is PM2.5 higher than 2019?
Unfavorable winds in 2020
A map of winds around Beijing as of February 13th show stagnating air around Beijing.
Weaker winds and fewer northerly winds can increase PM2.5. Data shows that wind—particularly northern wind—slashes PM2.5 in Beijing. Thus, less wind means fewer chances to blow away the air pollution. This, coupled with the atmospheric effect known as inversion, could explain why Beijing’s PM2.5 has been higher during the coronavirus lockdown.
Bottom Line on Beijing’s PM2.5 Levels During the Coronavirus Lockdown:
Studies Document Protective Effects of Purifiers, Masks
Despite the harms of PM2.5, studies have found that wearing masks prevents effects on blood pressure and heart rate variability. Placebo-controlled studies of air purifiers have found that reducing particulate in the home prevents harm to blood pressure, inflammation, and immune response—even among young, healthy twenty-year-olds.
Smart Air is a certified B Corp committed to combating the myths big companies use to artificially inflate the price of clean air. To help people living in polluted cities protect themselves, Smart Air provides empirically backed, no-nonsense purifiers and masks, helping to lower the cost of clean air.
Paddy is the CEO of Smart Air, running operations from Beijing. He’s has a Masters in aeronautical engineering from Bristol University, UK having specialised in aerodynamics. An advocate for open data, free information and transparent business, he spends his spare time promoting honest business and social enterprise.