Best HVAC filters and MERV rating guide. CDC-recommended MERV 13 picks. Filtrete, Honeywell, Nordic Pure, FilterBuy, AIRx tested on capture efficiency and pressure drop.

Best carbon monoxide detectors tested against calibrated CO sources. Kidde, First Alert, Nest Protect, X-Sense compared on accuracy, response time, smart features.

Best dehumidifiers for mold prevention tested in a 1,200 sq ft basement. Frigidaire, hOmeLabs, GE, Honeywell, Midea compared on capacity, drainage, energy use.

Best home air quality monitors tested against a calibrated reference. Airthings, Awair, Govee, Temtop, IQAir compared on PM2.5, CO2, VOC, radon, humidity accuracy.

Best HEPA air purifiers for allergies tested in a 200 sq ft chamber on PM2.5 and ragweed pollen. Coway, Levoit, Honeywell, Blueair, IQAir compared.

Manganese in well water — EPA health limits, infant exposure risk, and five best treatment systems tested at 0.18, 0.6, and 2.3 mg/L manganese loads.