A Breath of Fresh Air?

One consequence of cities being forced into lock-down in efforts to halt the Covid-19 pandemic has been a rapid and extraordinary improvement in their normally toxic air qualities (https://www.theguardian.com/environment/2020/apr/11/positively-alpine-disbelief-air-pollution-falls-lockdown-coronavirus). This has been the case in locations as diverse as Bangkok, Beijing, Bogota, Delhi and San Paulo. It just shows how quickly one could alter the health-damaging (including increasing mortality) effects of air quality but, I fear, that places will go back to the bad old ways as soon as their citizens can emerge