Your air conditioner doesn't provide fresh outside air to your home, but that doesn't mean it doesn't provide fresh air. The window unit contains an air filter that filters dust and debris, such as pet hair, from the indoor air before returning it to the house. This is why window air conditioning units provide filtered air to your home. Air conditioners cannot and do not purify the air.
The air filter located near the return air duct or air controller filters dust, pollen and other allergens. Air filters with a higher MERV rating are better able to filter particles and filter finer particles compared to lower MERV ratings. To ensure your window AC is providing clean air, make sure to unplug it, remove the front panel and clean the filter with a vacuum and warm water and soap. When used in conjunction with other best practices recommended by the Centers for Disease Control and Prevention, operating a window air conditioner can be part of a plan to protect yourself and your family.
However, if the air in your home is contaminated with volatile organic compounds and allergens, air conditioning is likely to worsen the situation. Window ACs can trap emissions from cars and flour in the air and remove dust particles by 45 percent for MERV 9 filters and 75 percent for MERV 12 filters. To ensure your window AC is providing clean air, make sure to open the vent to let out bad air and replace it with fresh outside air. If not properly ventilated and filtered, the air inside the house is dirtier than the air outside.