It's an Ill Wind

Impressive satellite images of China have revealed a dramatic decline in the levels of atmospheric pollution since the Covid-19 lockdown (https://www.theguardian.com/environment/2020/mar/23/coronavirus-pandemic-leading-to-huge-drop-in-air-pollution). The actual substance recorded is nitrogen dioxide and, whilst it is not a 'greenhouse gas', it is generated by the same processes that produce carbon dioxide. In addition, nitrogen dioxide is one of the pollutants that has been linked, along with particulates,  to respiratory diseases (and reduced lifespan) in humans, especially in people living near busy roads. Of course, any current health gains would have to be weighed against the considerable losses linked to the Covid-19 pandemic but it just shows what can be achieved in terms of air pollution over a very short period of time.