Air exchange is the most economical solution. You can’t stuff enough plants in a typical home to make a measurable difference and there are other pollutants su

Air exchange is the most economical solution. You can’t stuff enough plants in a typical home to make a measurable difference and there are other pollutants such as VOCs that air exchange will address. Here are the two least expensive options I know of: 1) Get a CO2 monitor and partially open a couple windows whenever the level is above 800 ppm. Cost: $60. 2) Get a good air filter such as an IQAir HealthPro+ and pair it with a ducting adapter such as https://www2.iqair.com/sites/default/files/documents/InFlowW125InstallationInstructions_105_20_20_11_Mar2012.pdf https://www2.iqair.com/sites/default/files/documents/InFlowW.... This will allow you to constantly exchange your indoor air with filtered fresh air. If you don’t want to install a wall intake for the duct, you can connect it to a window adapter like what is used for portable A/C units. Cost: $1,500.