If you have a heating or cooling systems that uses air ducts, you could have a problem.There are many duct systems that are poorly designed and installed that have
ability to bring pollutants into your home.
Some are ducts are located in wet or damp crawl spaces and basements.
I've seen some of these areas and some look like an open sewer.
Having ducts that are not properly sealed or insulated in these locations can draw moisture, mold, bacteria and even carbon monoxide into building.
Unsealed ducts have same effect as opening a hatch to these ares, only difference is that you don't see it and fan from heating or cooling appliance will force more of pollutants into living space at a much higher rate.
