Perhaps I am being very skeptical, but I am failing to understand how three months of lockdown all the sudden eliminates decades of pollution. Something does not add uphere.
Of course, 3 months of lockdown won't eliminate decades of pollution, but clearing the air and letting all the airborn suspended particles fall to the ground and pulling the dust out of the air makes it clear.
The other viewpoint is that you just don't realize how bad modern pollution is. In Toronto, ON, people are reporting being able to see Niagara Falls from a regular vantage point in the city after a few months of shutdown.
The high-atmosphere pollution remains, as does the soil and water and biomass pollution, but the low-level airborne particulate is heavily influenced by automobile traffic and industrial activity.
So CO2, which is of course a big deal now, isn't actually permanent, but its half-life is on the order of a couple of decades (the decay model is one of the big open problems in climate modeling) - hence the talk about how even if we stop emitting today, the problem will still be around. Whereas methane, a stronger greenhouse gas, has a half-life of only around 5-10 years.
Particulates have a much shorter half life before they settle to the ground; and, because they are a local form of pollution, they have a very short half-life before being blown away and diluted. If you've been following California news, this is why the massive pollution caused by recent forest fires went away within a few days of the fires dying out. If you're in any big and polluted city, this is why air quality can vary wildly from day to day with weather conditions and economic activity, leading weather forecasts to include an air quality forecast.
Imagine in your home city overcast clouds, dark skies. All of a sudden there's a downpour of a rainstorm. After a whole night of raining, the next morning, why does the sky appear blue and clear?
Is it that all of the clouds were destroyed and that they will never reappear again? No - it's because the clouds were carrying the mist and the water vapour, which "precipitated" out of the sky as liquid since the water droplets are heavier than air.
After it rains, the clouds disappear. The clouds didn't go away into nowhere. You can be skeptical about whether I'm writing about a magical statement, but you can observe yourself that after a period of intense rain -> the clouds go away and you can see the blue sky and clear across the city all of a sudden.
Will you be skeptical about this scenario as I described it?
It has to be replenished daily or you get scurvy.
The environment has scurvy.