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Reductions in air pollution due to COVID-19 in China have probably saved 20x the number of lives than have so far been lost to the virus. Does not mean pandemics are good, but rather that our economies absent pandemics are bad for health http://www.g-feed.com/2020/03/covid-19-reduces-economic-activity.html … (Thread 1/n)
A few weeks ago, NASA published striking photos showing the reduction in key air pollutants over China as a result of the economic disruption caused by COVID-19 in the country: https://www.earthobservatory.nasa.gov/images/146362/airborne-nitrogen-dioxide-plummets-over-china … 2. .
We know that dirty air is really bad for health. Like really really bad. Could it be that this reduction in air pollution actually resulted in more lives saved than had so far been lost to the virus itself? (3/n)
To answer this question, I first pulled some air quality monitoring data from US government monitors in 4 Chinese cities, and compared PM2.5 concentrations in Jan-Feb 2020 relative to the previous 4 years. As you can see, in 3/4 cities, air pollution was way down on average:pic.twitter.com/EEZ4wfICEL
Beijing was a different story, and that story is nicely explained here: https://energyandcleanair.org/why-does-the-smog-strike-beijing-even-when-the-city-is-closed-down/ … But averaged across all 4 cities including Beijing, I estimate a 15-17ug/m3 reduction in PM2.5 in Jan-Feb 2020 relative to past years. (5/n)
To be conservative, call this a 10ug/m3 reduction for 2 months. What were the health benefits of this very large air quality improvement? We need three numbers: change in mortality rate per change in ug/m3 PM, baseline mortality rate, and total population affected. (6/n)
For change in mortality rate, I use excellent paper by He et al 2016, who used quasi-experimental variation in air pollution induced by regulations put in place around the Beijing Olympics. They find huge effects for young and old people https://www.sciencedirect.com/science/article/abs/pii/S0095069616300237 … (7/n)
Conservatively (?) assume that only 50% of Chinese population affected - equivalent to no rural effect and only some urban areas affected. Assume that air quality improvement lasted 2 months and then disappeared. And finally, assume no-one btwn 5yrs-70yrs of age benefitted.
Using these numbers, I calculate 50k-75k reduction in premature mortality due to these air quality improvements. This is roughly 20x the current estimated number of direct deaths from COVID-19 in China. (9/n)
Are these numbers right? Impossible to know now, but they will actually be testable in a few years when more comprehensive mortality statistics are available. But I think they are perhaps not crazy, and could be conservative. Air pollution is really bad. (10/n)
Does this mean pandemics are good for health? No. Instead it means that the way our economies operate absent pandemics has massive hidden health costs, and it takes a pandemic to help see that. (/n)
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