According to the EPA,“indoor air pollution is among the top 5 environmental health risks”.These harmful effects from indoor air pollutants can appear immediately following exposure or show up years later after repeated exposure. Unfortunately, we cannot control outdoor pollutants, but we can control the quality of air inside. Normal indoor air has between 200,000 and 300,000 particles per cubic foot. Sub-micron particles have so little mass and weight they act more like a gas than a particle. The settling rate for sub-micron particles is less than 2 feet per 24 hour period. It is possible, with air circulating from your HVAC systems and movement of people,to  have these particles suspended indefinitely. Particles can be ingested or will become fomites, supporting direct contact infection and are a key driver of Asthma, allergies and COPD.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE)  published ground breaking documents on the transmission of viruses and microbes through the air and HVAC systems. The study identifies the following: adenovirus, influenza virus, rubeola virus (measles), meningococcal disease, mumps virus, pertussis (whooping cough), parvovirus B19, respiratory syncytial virus (RSV), rubellavirus, tuberculosis, and varicella (human herpes virus 3). Because of the shear scale of the particulate in the air, it is impossible to determine biological pathogens from particle. Hence, we must consider all particulates as potentially dangerous.