Another solution is to install a positive pressure system with high performance HEPA filters. This is especially recommended if you live in areas with very high air pollution.

Positive pressure systems can virtually achieve zero AQI inside even on the worst polluted days. You can read more here: [1] https://www.airgradient.com/blog/2020/01/08/positive-pressur... [2] https://seetheair.wordpress.com/2021/04/26/thailand-school-s...