To keep pollutants and allergens from circulating in living, work, and public spaces, air purifiers are worth considering. The appliance can filter dust, smoke, dander, and other disease-causing matter in a space. Today, various air purifiers are available, making choosing the right one tricky. One may even skip considering key factors, bringing home the wrong purifier for their living space. To avoid that, here are a few things to avoid when buying an air purifier: 1. Ignoring room size Air purifiers come with varying capacities. Some are designed to filter the air in a large space, while others are made for smaller rooms. In addition, there are portable air purifiers—capable of filtering only the surrounding air and not the entire room. With such a wide range of options in terms of filtering capacity, it would be a mistake to overlook the size of the room where the air purifier will be placed. So before buying an air purifier, one should take proper measurements of the room. 2. Not checking the air change rate The air change rate or air changes per hour (ACH) indicates the number of times the air purifier filters the entire volume of air in a room within an hour.