If you have central air and heating, you may consider a different option: upgrading to one of the furnace and air-conditioning filters we recommend. The EPA recommends filters with a rating of at least MERV 13, or, “as high a rating as your system fan and filter slot can accommodate,” and we recommend MERV 13 filters, too.
MERV stands for minimum efficiency reporting value, and it is a measure of how well a central-air filter removes particulates from the air. The basic MERV 1–4 filters often used in HVACsystems only capture pollutants visible to the naked eye, such as pet hair and dust bunnies. They typically look like a see-through mesh of blue or green string.
Higher-MERV filters, in the 8 to 13 range, are effective on fine particles that cannot be seen. They’re typically white, opaque, felt-like in texture, and pleated like an accordion.
In our guide to furnace and air-conditioning filters, our picks are all MERV 13. That means they are highly effective at capturing minuscule smoke particles (and even more effective on larger stuff like pollen and dust). Thanks to a 2024 California law that requires filter makers to publicly display their filters’ air resistance, we were able to identify highly capable MERV 13 filters that will nonetheless put very little strain on modern HVAC equipment.
Smoky conditions will clog the filters in as little as half the recommended replacement cycle (usually three months), so we suggest replacing the filters once the fires are over. And wildfires or not, if your system is more than 15 or 20 years old, it may not be up to the extra effort of medium-MERV filtration. In that case we recommend using a portable air purifier instead.
