We can purify inside air, why not use the same technology to purify outside air? [e-mail]?

Question

We build little purifers for home 's, why not the outside world?
Same with the water, We can purify drinking water and clean the water in fish tanks, why not use the same technology to clean rivers and lakes? If our govenment would stop giving themselves raise's and sending our money to other countries, and worry more about our health, we may not get sick as much.

Answer 1

That's very true, but that's a LOT of water and a LOT of air. It'd be *very* difficult and *very* expensive. And I don't think governments really care that much. No offense!

Answer 2

too much air. most blows to other countries anyway so it'd have to be global effort. rivers and lakes, still too big, dredging was proposed in my hometown, i heard that some suggest dredging the sludge from the bottom would stir up muck and cause more harm than good but that may have been the position of the corporate lobby that was going to have to do such dredging.