In addition to HEPA, you will also see activated charcoal or carbon filters on our list. Carbon is effective at removing smoke particles, gases, and odors from the air – just note that while these purifiers may provide an extra punch, they will likely come at a higher price.
Filter replacement cost
Since purifiers require a filter change every 3 to 12 months (time frame varies by brand and how often you run your machine), you will need to consider the cost of new filters. on top of the cost of the device. Each brand has its own type of HEPA filter, and they all come at different prices—some brands even offer a subscription discount for scheduled refills.
““It’s important to consider room size when choosing an air purifier,” says Mehrotra. “The filtration process can vary from product to product, but the goal for air purification is about five or six air changes per hour in the room, which is enough to reduce particulate levels in the room by about 70%.”
One way to measure an air purifier’s effectiveness is the product’s CADR, or clean air delivery rate – a measurement developed by the Association of Home Appliance Manufacturers (AHAM) in the 1980s. “CADR measures the amount of particulate-free air delivered into a room,” explains Mehrotra. “It reflects how effective the filter is and the amount of air that passes through the filter. The higher the clean air delivery rate, the larger the room that can be cleaned properly.”
Mehrotra adds that a good CADR is equal to at least two-thirds of a room’s area in square feet. For example, a room that is 10 feet by 15 feet has an area of 150 square feet. For this room, a good CADR rating would be at least 100 cubic feet per minute (cfm).