Air quality is an issue no matter where you live. Summer wildfires ravage large swaths of the American West, exhaust fumes from cars and buses fill cities, and even quiet country life means dealing with pollutants from agriculture. Rapid climate change has spiked pollen counts, making allergy season increasingly long and intense. 

You have very little ability to impact the air quality outside your home, but to fight indoor allergens like pet dander and outside threats like CO2 emissions, I’ve refreshed our guide to the best air purifiers after testing two dozen to find the best for every budget, room size, and purpose. To test every air purifier, I place it in various rooms in my Brooklyn apartment, from the kitchen to outside my cats’ litter box, manually checking the air with my own air quality monitor, and I use a decibel monitor to measure how loud the purifier is on the highest setting. I also put each in a sealed tent, using smoke pellets to time how quickly the air purifier clears the smoke in auto mode.