Indoor Air Quality: What Works, What's Theatre

Air quality is three problems, not one: particles, gases and moisture. Each has a different solution, and one device rarely solves more than one well.

For particles, filtration wins. A properly sized MERV 13 media cabinet with adequate surface area removes the vast majority of respirable dust without choking your blower. Stuffing a high-MERV one-inch filter into a slot designed for MERV 8 is the most common mistake we find.

For gases and stale air, dilution wins. A balanced ERV or HRV brings in filtered outdoor air and recovers most of the energy. No purifier destroys VOCs faster than fresh air replaces them.

For moisture, control wins. Keeping relative humidity between 40 and 50 percent suppresses dust mites, mold and most virus survival at once. That usually means a whole-home dehumidifier in summer and a properly sized humidifier in winter.

What we are skeptical of: undersized standalone purifiers marketed for whole-home coverage, ozone-generating devices, and duct 'sanitizing' sprays. If a product cannot show third-party test data at real room air-change rates, we do not install it.