Dramatic Changes in Air Quality
By Meteorologist Don Paul
Allow me to preface this article by explaining the presentation of data here is not done with the purpose of finding a “silver lining” amidst this pandemic. The changes in air quality are, simply put, a byproduct of one of the worst human tragedies in the modern era.
The reduction in air pollution does have benefits, to be sure. The benefits go beyond improved visibility, as can be seen in this photo comparison in India: https://thenypost.files.
In Los Angeles, this first image is from last June: https://www.dropbox.com/s/
The second image is from April 20th this year: https://www.dropbox.com/s/
There have been studies performed by such institutions as the Harvard School of Public Health demonstrating an increased vulnerability to respiratory infections in general and COVID-19 in particular in locales where the air is more heavily polluted. The pollution may consist of particulate matter or irritant gases, or both, though particulate matter is known to have a larger impact. However, this link needs to be kept in perspective as well, particularly for smokers. Regular smoking is far more damaging to lung tissue than air pollution, on an entirely different scale. It is well known smokers are more vulnerable to COVID-19 lung infection than nonsmokers. This University of California at San Francisco article from early April outlines the issue: https://www.ucsf.edu/news/
Since this UCSF article was written nearly a month ago, virologists and doctors have since seen growing evidence of the viral assaults on patients’ immune systems leading to widely dispersed organ failures in some patients, including liver, kidney, and heart tissue damage as well as major blood clotting leading to strokes. So, COVID-19 seen originally as mainly a serious and often deadly respiratory infection is now known to pose multiple threats in other organ systems. All this said, the reduction in air pollution which has occurred may have at least a minor impact on reducing respiratory transmission in exposed people due to limited reduction in lung inflammation. I participated in a webinar for science journalists last week on this topic. On a personal note, I have to say I came away from the webinar knowing what I already knew about air pollution having those irritant effects, but also noting the drastic reduction in air pollution in most parts of the world will make it less of a contributing transmission factor as the human tragedy continues to unfold.
The drop in fossil fuel usage is dramatic. This April 2019 to April 2020 comparison not only shows the reductions, but also increased energy production from alternative sources: https://www.
Within all fossil fuels, the pandemic has accelerated the reduction in coal usage with a greater acceleration in the use of cheaper natural gas which, at least, produces only about 40% as much carbon dioxide as does coal combustion. Carbon dioxide is the most important greenhouse gas from human activity, but another important gas in both terms of pollution and greenhouse effect is nitrous oxide. A British study shows a sharp drop in NO2 emissions as well, year to year: https://ichef.bbci.co.uk/news/
As for carbon dioxide, industrial and transportation emissions are down substantially. CO2 is not a pollutant in terms of toxicity and respiratory inflammation, but its impact on a mean warming climate is primary. In China, measurements earlier in the pandemic when that nation was having its worst impact with shutdowns, carbon dioxide emission there were down about 25% based on both ground measurements and a special wavelength used in satellite imagery. Since that time, China’s emissions have ramped up again as many shut down plants have been reopened. The crushing economic impacts in the U.S. and much of the rest of the world continue to keep carbon emissions down substantially. Since the transportation segment of carbon emissions has surpassed the industrial and energy segments, the reduced ground and air travel in the U.S. and Europe have contributed to substantial downward trends. Interestingly, however, carbon dioxide if not absorbed by the ocean or metabolized by vegetation has a very long “shelf life” once it gets up higher in the atmosphere.
Estimates in the complex calculations to determine CO2 longevity aloft used to approximate 30-50 years per molecule. There is abundant evidence now some carbon dioxide from excess anthropogenic/human emissions can persist for thousands of years. That is why the regularly updated carbon dioxide measurements displayed monthly by NASA have not yet shown a significant reduction: https://climate.nasa.gov/
Scientists and much of the public alike know the improvements in air quality and the reduction in greenhouse emissions are temporary, and the costs being paid for these improvements are nothing short of horrific. Again, I’m not presenting any of this as a trade off. A warming climate has already imposed significant costs on humanity and the environment, but those costs pale compared to the disastrous price in human and economic health facing the world during the pandemic.