Every forced-air heating system, like a furnace, has a filter (or it should). When you run your heater, it first sucks in air from around the home and then heats it before blowing air back out to the rooms. Any dust or debris in the air could get sucked in and forced out with it, but the furnace helps to prevent this and protect your heater from damage that could be caused by that incoming debris.
However, this doesn’t mean that air coming out of the vents is always healthy. With winter comes viruses, bacteria, and other potential causes of illness that are airborne, so you should consider taking additional steps to protect your indoor air quality. Here are our suggestions.