Smoke is good for you!
When I was growing up there were hundreds of mills belching out black smoke 24/7, all the houses had coal fires and the wind would blow down the chimneys and fill the room with smoke, pea-soupers were an adventure to be enjoyed yet kids didn't have asthma or eczema, come the Clean Air Act suddenly half the kids had asthma and the other half had eczema. What more proof could anyone want?
Bring back coal.... coal means health.