“Clean” rooms, in which air remains contained in a closed system for filtering rather than mixing with the rest of the facility, are in high demand at hospitals. Enter the OptiClean ($2,000–$4,000), a mobile air purifier built by Carrier that has two air-scrubbing functions. It can turn any room into a so-called negative air-pressure space to prevent potentially contaminated air from flowing out, pushing it instead through a high-efficiency HEPA filter before releasing it back into the room. Or, it can simply filter out pathogens from a room. So far, the company has 15,000 orders for the units from hospitals as well as schools, universities, offices and other buildings looking to provide safe indoor environments. —Alice Park