A homemade air purifier can help against smog in Philadelphia from wildfire smoke particles

In the early months of the COVID-19 pandemic, air-quality experts recommended the use of air filters to help reduce the spread of virus particles.

Those filters also work for trapping the airborne particles from the Canadian wildfires, researchers say.

But commercial air filters can cost hundreds of dollars. Another option is to build one yourself, using a standard household box fan and $50 to $60 in supplies.

The Inquirer made one in October 2020, with the help of handy folks at the Hive76 "maker space" in Kensington.

In a November 2022 study, researchers found that these do-it-yourself devices were effective against simulated wildfire smoke in a laboratory setting.

» READ MORE: How to make your own air filter using a box fan