Air pollution is reduced by misty light rain. The process is called wet deposition. Swarms of electric drones could mist cities with water every morning to reduce air pollution. The technology should be feasible and economically justified.
This is probably great for the humans involved, but it occurs to me that using misting to lower air pollutant levels while not actually reducing air pollution just means that we're dumping those pollutants into the watershed instead.
*Total* urban area in the world was around ~3.5M km^2 in 2010[0], or 1% of total ocean area. Daily evaporation dwarves anything a couple thousands of drones can do in the morning.
Shouldn’t it be measured against human GHG activity like transport and agriculture, and not standard operation of the planet whether we exist on it or not?