Cooper and associates have learned that “One of the most widely available technologies to clean the air in homes of particulate matter of less than 2.5 µm in diameter (PM2.5), known to have negative health impacts, are portable home air purifiers (HAPs). . . . ; occupants reported the HAPs to have a ‘cooling’ effect, which may explain why the predominant driver of HAP use was thermal comfort, rather than IAQ, in all three cities [where data were collected]. The latter…