Ask HN: Environmental impact of the COVID-19 Lockdown?

Check the ESA Satellite imagery here (Northern Italy) to visually appreciate what has changed (this is mainly about nitrogen dioxide):

https://www.esa.int/ESA_Multimedia/Videos/2020/03/Coronaviru...

There have already been multiple items here over the past weeks indicating that China's CO2 emissions dropped tremendously after Wuhan and the surrounding areas went into their lockdown.

Measurable, yes, some of the items linked to satellite imagery showing before and after results and it was quite obviously measurable.

It will likely result in some very interesting studies, like that of Marine Life in the North Atlantic after the attacks on New York during September 11th.