Secondhand smoke in front yard and back yard

In the front of my home, I am a few doors downwind from a tenant chain smoker who smokes on his stoop all day long in every season. For years, my home would fill up with smoke each time I opened the windows. have tried talking with him about moving further away from the homes to a more commercial bit of the block but he became very aggressive and said I was out of line. This was the year someone in our home was diagnosed with a never-smoker Stage 4 lung cancer. I decided to keep my front windows closed…in every season…and retreated to the backyard. We are into our third summer now. Now we have new neighbors in the back. They just built a beautiful deck and have parked their lounge chairs right up against the fence…and are themselves chainsmokers. Even sitting outside for brief amounts of time results in our cancer survivor having to use their nebulizer and other supports. Now we are limited from using our backyard as well. Any advice?