Air purifiers: CADR, room size and replacement filters

Keep the particle name attached to CADR

Clean air delivery rate, or CADR, describes particle removal. Compare the same named smoke, dust or pollen measure; these represent different particle sizes. The EPA's buying guidance notes that CADR is usually measured at the highest fan speed.

Coway's Airmega 250 page lists 249 CFM for smoke, 261 for dust and 230 for pollen. Levoit's Vital 100S-P page lists 143 CFM without naming a particle type in that specification. CompareFoundry keeps that value separate rather than assigning it to a smoke, dust or pollen column.

Read room area together with air changes per hour

Air changes per hour, or ACH, describes how many room volumes the stated airflow corresponds to in one hour. A coverage claim becomes more useful when the area, ACH, ceiling assumption and fan condition are all available.

Coway lists the same Airmega 250 for 1,860 square feet at one ACH, 930 at two ACH, and 465 at four ACH. Levoit lists the Vital 100S-P at 222 square feet for 4.8 ACH. Comparing 1,860 with 222 alone would mix different conditions.

Measure floor area and check ceiling height. Open adjoining areas add to the space being treated; higher ceilings add air volume. The EPA advises sizing for the space and allowing for ceilings above eight feet. Keep air inlets and outlets clear.

The Coway Airmega 100 is listed for 405 square feet at two ACH, while the larger Airmega 400S is listed for 1,560 at two ACH. The Winix 5510 uses a 392-square-foot rating at 4.8 ACH in its current documentation. Keep those rates visible when narrowing the catalogue; the largest area number alone does not identify the right model.

Some product pages present room claims without a common air-change basis. The Blue Pure 511i Max table gives 237 square feet at 4.8 ACH, while its title advertises 465 without a verified matching rate. The Core 600S-P page gives both 635 square feet at five ACH and 606 at 4.8 ACH. Its page lists 49 W, but the linked US manual lists 66 W for the same model. Read those source notes before relying on a room or power limit; unresolved values do not pass the catalogue's corresponding filters.

Choose a fan setting you can live with

A quiet or sleep mode can move less air than the setting used for the published CADR. Ask whether you would run the needed setting while sleeping or working. Manufacturer noise figures need their measurement conditions; we have not tested these models for noise or particle removal.

Levoit's Vital 100S-P listing qualifies its HEPA performance statement to Sleep Mode. Keep that qualification attached to the claim. A filter description by itself does not establish the purifier's airflow in every mode.

Check the filter you will replace

Find the exact replacement part for the selected model and check its current price, availability and maintenance instructions. Coway identifies a washable pre-filter and a separate Max2 filter for the Airmega 250. Levoit likewise distinguishes its washable pre-filter from replacement filters. Do not assume the main filter can be washed.

Count the filters as well as identifying the part. Airmega 400S uses two Max2 filters, with the 400/400S replacement sold as a two-piece set. Airmega 100 uses a single combined filter, and Winix 5510 names Filter Q. Confirm the model and quantity before comparing replacement costs.

Keep particle removal separate from odor or gas removal. CADR does not rate gases; the EPA advises looking for substantial activated carbon or another suitable gas filter. It also advises avoiding devices that intentionally produce ozone.

In the air purifier comparison, check the coverage and ACH rows together. If a required CADR field is unknown, open its source note before deciding whether the product suits your room.