Which device is primarily used to regulate air quality by maintaining temperature and humidity levels?

The device that is primarily used to regulate air quality by maintaining both temperature and humidity levels is an air conditioner. Air conditioners function by cooling the air and often include a dehumidifying component, which helps to remove moisture from the air, thus maintaining an optimal humidity level. This dual function is essential for creating a comfortable indoor environment, particularly in areas that experience high humidity or during warmer months.

While a dehumidifier specifically targets humidity control and an air purifier focuses on filtering out pollutants and allergens from the air, they do not regulate temperature. A heater, on the other hand, is primarily used to increase temperature but does not address humidity levels. Therefore, the air conditioner stands out as the device that maintains comfortable and healthy air quality through the regulation of both temperature and humidity.