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We've managed to keep our house smoke-free this year. Important because my son has asthma. Here are my tips:
1. Find and seal all the places where air can enter your house. Old leaky windows. Bathroom, kitchen, laundry fans might vent outside. Attic drop-down doors. 3M sells a window insulation kit that's 
. https://www.amazon.com/3M-Indoor-Insulator-Kit-2-Window/dp/B000AXXCUC/ref=asc_df_B000AXXCUC/?tag=hyprod-20&linkCode=df0&hvadid=198099432697&hvpos=&hvnetw=g&hvrand=11248878477610527766&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9031922&hvtargid=pla-368263637696&psc=1
. https://www.amazon.com/3M-Indoor-Insulator-Kit-2-Window/dp/B000AXXCUC/ref=asc_df_B000AXXCUC/?tag=hyprod-20&linkCode=df0&hvadid=198099432697&hvpos=&hvnetw=g&hvrand=11248878477610527766&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9031922&hvtargid=pla-368263637696&psc=1
2. Not all air purifiers are created equal. Last year I had whatever was at Target. This year I bought Wirecutter's picks: Coway Mighty and Blueair 211+. Both are working very well. https://www.nytimes.com/wirecutter/reviews/best-air-purifier/
3. I don't trust sensors on air purifiers, so I bought the Purple Air indoor air sensor.
4. Check if you can run your AC, ideally with a good filter for PM2.5. Don't run an air pump that draws air from outside. Don't run AC with big gaps in the ducts that let in air under your house or in your attic. Test it first.
5. When air is good, let in as much fresh air as possible. I rely on the Purple Air map because it's much more real-time than any other source.
