How Did the Lockdown Affect China's Air Pollution Levels?

Data collected by NASA satellites has demonstrated that air pollution across the country has fallen as a result of the coronavirus outbreak. Many parts of the country only came out of a total lockdown last week, which lasted for a whopping 76 days and saw people confined to their homes in order to avoid the spread of the deadly virus.

But while the extreme measures may have hampered the quality of countless lives and done significant harm to local and national economies, it seems to have worked wonders for Chinese air quality. Concentrations of nitrogen dioxide (NO2) in particular fell dramatically as a result of the quarantine period, offering a window into how rapidly emissions can be cut when human health is at imminent risk.

The Wuhan effect

As the epicentre of the outbreak, Wuhan City in Hubei Province has featured prominently in the news over the first three months of the year. Although the first diagnosis of COVID-19 occurred on December 31^st 2019, it took over three weeks for the authorities to take meaningful action. However, when it finally arrived on the 23^rd January, the response was as extreme as it was effective.

Initially, the restrictive measures only applied to Wuhan’s 11 million residents, but as the virus continued to spread across the country, so too did the lockdown. Of course, many other countries have since followed suit, including the entirety of India’s 1.3 billion populace. At present, around a third of the global population finds their movement restricted by national measures in some form or other.

Self-isolation has not only proven to be effective in curbing the spread of the disease – China reported no new daily deaths earlier this month for the first time since January – but it has also been incredibly effective in managing emissions of nitrogen oxides (NOx). In particular, NO2 concentrations across Wuhan fell significantly as a result of the ban, with similar gains witnessed in other parts of the country as well.

Good news for the environment and for human health

NO2 is most commonly produced when combusting fuels, whether that be in the petrol or diesel in a passenger car or the oil, gas or coil in a fossil fuel power plant. Once it enters the air, it’s a damaging contaminant in its own right – but it’s also instrumental in the creation of more harmful pollutants like ozone and particulate matter (PM). PM2.5, so named for the microscopic diameter of its particles – is especially easy for humans to inhale and can wreak havoc on the human body.

Fortunately, technology has advanced to the point where we are better equipped than ever to monitor levels of PM and the NASA data has shown that the contaminant is in sharp decline since the quarantine period began. Chinese Lunar New Year, which took place at the beginning of February, always precipitates a spell of reduced pollution, since businesses close for the holiday, but levels soon spike after it is finished. That has not happened so far this year.

Meanwhile, Chinese emissions of carbon dioxide (CO2) were also down according to the NASA images. Analysts have said that the country produced around 30% fewer CO2 emissions in between February 3^rd and March 1^st as it did in the same timeframe last year. That’s equivalent to approximately 200 million tonnes of carbon, which is no insignificant amount of greenhouse gas.