Air Quality over China Improves After Coronavirus Quarantine

March 12, 2020

NASA satellite observes 'significant decreases' in nitrogen dioxide as factories shutter and workers stay home.

NASA satellite observes 'significant decreases' in nitrogen dioxide as factories shutter and workers stay home.


This photo taken on February 27, 2020 shows a man wearing a face mask as he sits along rows of closed shops near the Zhejiang Xuda Shoes Co. factory in Wenzhou. - The number of new cases of the COVID-19 coronavirus in China has declined in recent days, but infections in other countries have gathered pace. (Photo by NOEL CELIS / AFP) (Photo by NOEL CELIS/AFP via Getty Images)

Story Transcript

Kim Brown: Welcome to the Real News. I’m Kim Brown. As Corona virus enters into the pandemic phase, and governments around the world scramble to contain it, there has been an unexpected, though probably predictable, positive effect. Over certain areas of China where the virus has struck the hardest, NASA satellites have detected significant decreases in levels of nitrogen dioxide in the air. Obvious question, what’s nitrogen oxide? Let’s have a listen.

Speaker: Nitrogen dioxide is a gas emitted during the combustion of fossil fuels. It’s released from the tailpipes of cars and the smoke sacks of power plants. Together these emissions affect the quality of air we breathe. Since 2004 an instrument aboard NASA’s Aura satellite has measured levels of nitrogen dioxide in Earth’s atmosphere. In 2014 we released satellite images that show how environmental regulations have led to reductions in nitrogen dioxide over major US cities. Now we created global maps that allow us to see how levels have changed around the world over the last decade.

In China we see an increase in levels over most of the country due to a rise in coal use for power generation, but decreases for some cities like Beijing, where a growing middle class is now demanding cleaner air. In the US the only increases are in regions with intensive oil and natural gas extraction, including fracking. In North Dakota and Texas we see increases of 30% in some areas.

By monitoring levels of nitrogen dioxide from space we can see and quantify the effects of things like energy usage, environmental policy, and even civil unrest, on air quality across the globe.

Kim Brown: And joining us today is Dr. Bryan Duncan. He is an atmospheric scientist in the Atmospheric Chemistry and Dynamics Laboratory at NASA Goddard Space flight center right down the street. He is project scientist for the NASA RS satellite mission, which observes atmospheric constituents in the troposphere, stratosphere, mesosphere. He has expertise in air quality and tropospheric trace gas composition. He’s a member of NASA’s Health and Air Quality Applied Sciences team, which facilitates the use of NASA satellite data by health and air quality communities. He joins us today from Davidsonville, Maryland. Dr. Duncan, thank you so much for being here.

Dr. Bryan Duncan: Oh my pleasure.

Kim Brown: So I follow NASA on Twitter because, interesting. But when I saw this post on the earth observatory page, which said airborne nitrogen oxide levels plummet over China due to the Corona virus quarantine and subsequent economic slowdown, I thought that was kind of sounds like a big deal. So tell us, is this a big deal, little deal or no deal?

Dr. Bryan Duncan: It is a big deal, but first, let me start off and say that NASA, most people don’t know this, but NASA has a fleet of satellites that observe the earth. So they’re orbiting the earth right now, anywhere from 20 or more. They observe all types of aspects of the earth, whether it’s the ocean, the biosphere, vegetation, ice sheets, and so on. And one of the, or several of the satellites measure various types of air pollutants. And one of those air pollutants is nitrogen dioxide. Okay, so you heard in the video that nitrogen dioxide is produced whenever we burn anything like fossil fuels. So it’s coming out of our tailpipes and our smokestacks.

In China we have a longtime record now, starting in about 2005 to the present. And what we saw in the data in China is that the pollutant levels increased quite a bit from 2005 to around 2011, 2012, and they began to decrease again until today. And that’s because the Chinese government began requiring emission control devices on the sources of nitrogen dioxide pollution. And that is the cars. So they were requiring more efficient cars, emission control devices on power plants.

So the levels, so we’ve been able to use these satellites to look at how air pollution has been changing over time in China, and we’ve never seen such a very sharp decrease as this, over this short period of time, on the matter of just a few weeks.

Kim Brown: Exactly. I don’t mean to cut you off, but I want our viewers and people who are listening to the audio broadcast to take a look and listen at the satellite photos because it’s pretty striking. The photos taken between January 1st to January 20th over China, I mean, the block was clearly hot. We’re seeing a lot of yellows, reds, oranges. But the same period, or rather a different period, February 10th through the 25th, over the same area, we see whites and blues. And you said you and your team, you guys are pretty surprised to see this.

Dr. Bryan Duncan: Well, we were surprised to see, we expected to see a decrease, but not this much. It just indicates how the Chinese government, how restrictive they were in their efforts to contain the virus by shutting down factories, requiring people to stay at home. And that shows very clearly in the data. One thing that’s interesting about the data I would like to point out is that historically over the last 15 years that we have a data record, nitrogen dioxide pollution emissions tend to decrease just before the lunar new year holiday. And that’s at the end of January this year. And that happened this year. But the thing is is that the pollutant levels didn’t increase again after the holiday was over, as they did in typical years. In fact, they went down for about three more weeks, which is very unusual and stood out, and it was very clear to us that something was going on on the ground and it was big, very significant.

One thing I would like to point out is that the air pollution emissions just in the last week or so seemed to be increasing again for nitrogen dioxide and that could indicate that some limited economic activity is resuming. And that’s at least consistent with news reports that I’ve heard that yes, some factories are beginning to reopen in a limited fashion.

Kim Brown: Well, I’m glad you brought that up Dr. Duncan, because that was my bummer question. You know, once fears have calmed down over the Corona virus spread, and the factories reopen and people start driving to work and shopping, how long do you think it will take for the nitrogen dioxide levels to return to the pre quarantine levels?

Dr. Bryan Duncan: I think that absolutely depends on the Chinese government and when they began to lift restrictions. And I can’t predict how that will play out.

Kim Brown: So, as you mentioned, you have not seen this precipitous drop over a relatively short amount of time over the same area. But I’m curious on the spectrum of greenhouse gases, why is NO2 bad for humans and other life on earth to be breathing?

Dr. Bryan Duncan: Okay. Nitrogen dioxide is not a greenhouse gas. It’s an air pollutant. It’s very unhealthy to breathe, and that’s why, for instance, the US environmental protection agency has been regulating it for decades. The second thing is that nitrogen dioxide, most people don’t know this, is a necessary ingredient for the formation of another very important pollutant called ozone. And ozone at the surface when it forms in photochemical smog, think about just smog in a city, ozone is formed, it’s very unhealthy to breathe this, it actually can chemically react with our lungs and burn our lung tissue. And this damage is permanent.

So somebody who’s older like me will have, well my lungs will show significant damage from ozone, relative to a younger person for instance. I’ve been exposed to ozone a lot longer than say somebody that may be 20.

Kim Brown: So Dr. Duncan, the sad reality is that capitalistic industrialization at this point in our human existence is incompatible with clean air and water. But if we could, let’s delve into the realm of fantasy, because let’s say if Los Angeles were to experience an industrial slowdown like we’ve seen over China, how would that be felt? How would people notice that? What would that look like?

Dr. Bryan Duncan: Okay, well, I’ll turn this sort of in a different direction. I’ll change your question a little bit. I think the best way to look at this is environmental regulations started to go in to effect primarily in the ’70s, there were other environmental regulations before that, to try to combat air pollution. And since the 1970s our air quality has improved dramatically in the US and is improved also in Europe and Japan because of similar efforts to improve environmental pollution.

So compared to what our air quality was 30 years ago, or 40 years ago, things are so much better. And on the order, for instance, just in the last, since about 2007, eight, nine in that period, nitrogen dioxide levels in the US have dropped anywhere from 20 to 60% in most American cities. So we have seen such precipitous drops, but that’s because of emission control devices, more fuel efficient cars, and other efforts to reduce air pollution. What we’re seeing in China is a totally different story.

However, they have made significant efforts to improve their air quality through emission control devices in the last decade and it’s showing.

Kim Brown: Do we have to expect pandemics or other catastrophic type of events to deter human activity in the sense of factories, power plants, people driving their cars, because again, the notice was so stark over a relatively short period of time, it just looked like I was looking at a snapshot of the answer to perhaps some of our climate change problems.

Dr. Bryan Duncan: Oh, okay. Well, that’s getting a little bit out of my area of expertise because I would say that there could be, say other efficiency controls added to power plants, to cars, to improve it, to make it less polluting. And I think that’s definitely something, a direction we need to go in, because our air, even though we’ve made a lot of improvements in the US, and a lot of improvements in China in the last decade, the air is still not clean. And we do need to consider additional efforts going forward.

Kim Brown: All right, well we’re going to leave the conversation there. Dr. Bryan Duncan, we certainly appreciate your time. He’s a research scientist in the Atmospheric Chemistry and Dynamics Laboratory of the NASA Goddard Space Flight Center. He is project scientist of the NASA Aura satellite mission and a member of the NASA Health and Air Quality Applied Sciences team. Dr. Duncan, we appreciate your time today. Thank you so much.

Dr. Bryan Duncan: My pleasure.

Kim Brown: And thank you for watching the Real News Network.