Coronavirus Has Slashed Global Air Pollution. This Interactive Map Shows How.

The Covid-19 pandemic has changed the world, stopping progressively larger geographic areas and parts of the economy in an effort to slow the spread of the virus.

The effects were profound on the ground, but government-imposed lockdowns have also recreated the atmosphere. Satellite data from China, the first epicenter of the outbreak, and Italy, the second hotspot, has seen a major drop in pollution due to closures that limited the movement of people and goods and factories to produce items. With the pandemic becoming more prevalent in the United States, Americans have started to move less because mayors and governors have adopted similar measures.

In an effort to track the impact, Earther collected one interactive map to investigate changes in air pollution not only in the United States, but worldwide. The map runs on Google Earth Engine and uses data collected by the European Space Agency’s Sentinel-5P satellite, which orbits the Earth and records various types of data. It contains four snapshots from December 2019 to March 20, 2020. The Sentinel satellite data shows nitrogen dioxide, a useful proxy for human activity.

“Nitrogen dioxide is produced by burning fossil fuels and is therefore often used as an urban polluter,” Barbara Dix, an atmospheric researcher at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, told Earther in an email. “Burning fossil fuels immediately releases a lot of nitrous oxide and a little nitrogen dioxide (often referred to together as NOx), but nitrous oxide is quickly converted into nitrogen dioxide in the atmosphere. Nitrogen dioxide is easy to measure by satellite. ”

Since fossil fuels power everything from cars to electricity, satellite images of nitrogen dioxide really show the impact that covid-19 has on society like no other dataset. There are clear signs of the virus’s impact around the world and we will discuss some American examples below. But it’s also important to make a few caveats like you scroll the map and look at the before and after pictures.

The data presented here is a series of one-day snapshots. Weather patterns can blow and spread pollution while it rains, and even the level of sunshine can further change Sentinel-5P’s measurements. There are also natural sources of nitrogen dioxide that can affect measurements. The data in Google Earth Engine is not necessarily quality filtered. Dix noted that means clouds can mess around with measurements, which could be why the interactive map has some rougher-looking areas, like northern New England in March or signs of pollution in the Seattle area where there may be is not much. It will take researchers time to really dive into and filter the data to gain an understanding of the impact of covid-19 on air pollution. Despite these caveats, trends in many major cities in the United States are stunning and clearly at least partially linked to the changes imposed by the Covid-19 pandemic.

“The rapid decline we see in nitrogen dioxide from covid-19 is unprecedented,” said Dix. “We are now witnessing a worldwide experiment in which one emission source is rejected quickly (NOx), while other sources are still going up or will decrease more slowly. This is where much atmospheric science comes from. ”

“I imagine that the air pollution monitoring data collected during the closure of Covid-19 will be helpful to our fundamental understanding of the sources of pollutants (economic sectors, natural emissions, etc.), the chemistry of nitrogen dioxide, ozone and particulate matter to be tested. and short-term effects on air pollution health and ecosystem, “Viral Shah, a postdoctoral researcher at Harvard, told Earther in an email.


California became the first state in the United States to issue a shelter-in-place order on March 19, although many cities decided to close earlier. The resulting drop in pollution from January to March in the state’s major metropolitan areas is grim. Los Angeles is a huge source of pollution due to car culture, and the steep drop in pollution in the city is evident. Traffic reports backup the satellite data. The Bay Area and San Diego also saw pollution spread in the light of a reception center.

The effects also spread across the border. Tijuana – closely linked to San Diego – saw the pollution disappear to practically nothing. Ditto for El Paso and Juarez visible further east. The Mexican and U.S. governments have agreed to partially close the border in an effort to stop the spread of Covid-19.

Even though they aren’t in lockdown states, Salt Lake City, Phoenix, and Las Vegas all have varying degrees of restrictions on residents and businesses. And again, the map makes it clear that this is likely to affect pollution.

The northeast corridor

The densely populated area stretching from Boston to Washington, DC is the epicenter of the U.S. coronavirus outbreak and also a center of economic and political activity. It is also an area where states and cities have quickly transitioned to shut down nonessential services to slow the spread of the virus.

While New Yorkers aren’t as car-dependent as their Los Angeles counterparts, there are still plenty of vehicles that normally stand on NYC roads and dense clusters of buildings that emit pollution. Ditto for Boston, Philadelphia, Baltimore and Washington, which normally form a chain of pollution along Interstate 95. With Covid-19 lockdowns, the chain is broken.


The area from Minnesota to West Virginia is the largest state cluster with lockdown orders in effect. Six governors have already locked their states and will do so soon.

The data here is a bit louder, but some clear trends are visible. Autocentric Detroit has a big dip in pollution. Chicago’s vast pollution is also disappearing.

The US-Canadian border, like its southern counterpart, is also closed outside essential services and trade. The Ontario province called for closure at the end of last week, and the consequences of these moves are also appearing on the map. Pollution is also being wiped out in the neighbors of Detroit, Windsor and Toronto further east.

A strange blip is a pollution hotspot in Kansas near Emporia. That could be one of the data artifacts Dix mentioned, or the nitrogen dioxide emissions that may be related to fires that burn through the state’s grasslands each spring.


Even though the south is slow to act, and the Lieutenant Governor of Texas has actively advocated Monday old people die the effects are still noticeable there to save shareholder value. Although the data is a bit noisy, nitrogen dioxide emissions in Houston, a hot spot for the petrochemical industry, appear to have declined. New Orleans – another petrochemical hotspot that is the only southern state to request a total shutdown – also seems to have seen a drop in pollution.

This may be related to the fate of fossil fuels, which have fallen as a result of a price war triggered by Saudi Arabia and falling demand as the world economy slows. Sharp dives are also visible in Mexican cities such as Monterrey, which may be related to the closure of the border. View the full map here.

Covid and migraine #Short


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