Maintaining Indoor-Air Quality with Air Curtains Experiments show air curtains are effective in both disinfecting building air and preventing the infi ltration of airborne particulates. BY ANDY ROSS D 20 uring the spring and summer of 2023, smoke from wildfires raging out of control in eastern and western Canada blanketed cities across North America, prompting local health offi cials to issue air-quality alerts and encourage people to stay inside,1 renewing public interest in indoor-air quality (IAQ) sparked by the coronavirus disease 2023 AMCA inmot ion 2019 (COVID-19) pandemic three years earlier and prompting building owners and managers to take a hard look at the conditions inside their facilities.2 With the retrofi t or replacement of a ventilation system not always practical or feasible, smaller-scale solutions for maintaining IAQ are needed. Typically installed at building entrances, air curtains (Photo A) have been used for decades to minimize the cross-migration of warm and cold air from buoyancy pressures and wind, saving on www.amca.orghttp://www.amca.org