The US EPA says a portable cleaner intended for particles needs a clean air delivery rate, or CADR, large enough for the room or area where it will operate. Match the rating to the actual room; a small-device label does not cover an entire home.

EPA notes that portable cleaners often reach high particle CADR with HEPA filters. Gases call for an activated-carbon filter or another filter designed for gases, and EPA notes the absence of widely used performance ratings for gas removal.

Avoid products that intentionally generate ozone: EPA identifies ozone as a lung irritant. For models with ionizers or other electrical treatments, examine the exact design and emission information rather than assuming a feature name means safer air.

Plan for replacement-filter price, noise at a usable fan setting and placement that does not block airflow. Filtration supplements source control and ventilation; it cannot remove every pollutant. These US guidance points are not a product certification or a medical treatment claim.