The more I cover air purifiers, the more go big to go quiet comes to mind. At 2.5 pounds, the Briiv 2 Pro Air Filter is the smallest air purifier I’ve tested, though it’s far from the cheapest. I don’t usually review air purifiers that are not CARB-certified (California Air Resources Board), but I was intrigued by the Briiv. Photograph: Lisa Wood ShapiroPuroair 240 HEPA Air Purifier for $159: At under 9 inches tall, the Puroair 240 is a tiny air purifier. And like most of the air purifiers we review at WIRED, it’s California Air Resources Board Certified or CARB-certified.