Briiv 2 Pro Air Filter for £399: There are big claims in Briiv’s 2 Pro Air Filter’s small package. 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. Photograph: Lisa Wood ShapiroPuroair 240 HEPA Air Purifier for $159: At under 9 inches tall, the Puroair 240 is a tiny air purifier. Shark NeverChange Air Purifier for $250: A lot of what was true for the Shark NeverChange Air Purifier Max is true for the line’s smaller NeverChange. And while the P5001 is California Air Resources Board or CARB-vertified as a mechanical air purifier, the EPA does not recommend catalysts in air purifiers due to their limited effectiveness.