Healthy House IAQ

By John Bower

There are several ways to minimize indoor air pollution, but each has limitations. To determine what works best in your situation, it helps to organize pollutants into three

Biologicals  

Dust mites , mold spores, mildew , pollen, animal dander , bacteria, viruses.

Gases 

Formaldehyde , combustion by-products , volatile organic compounds.

Metals

Lead paint , arsenic in treated lumber.

Minerals

Asbestos , fiberglass insulation , airborne calcium particles from humidifiers.

Radiation

Radon , electromagnetic fields, radioactive material in some smoke detectors and compact fluorescent lights.

Vapors 

Mercury vapor from biocides in paints. Excess water vapor can cause an increase in biologicals and outgassing of formaldehyde.

Pollutants that originate from "things" inside the living space include outgassing or particulates released from home furnishings or building materials directly exposed to the interior living space (paints, wall paneling, cabinetry, etc.), evaporation from cleaning and home-maintenance products, mold spores from colonies growing within the house, pollen from house plants, etc. The best way to minimize pollution from many of these sources is to simply eliminate them, mainly by using less polluting alternatives. For example, choose low-outgassing paints and finishes, furniture without long-term formaldehyde emissions, less-noxious cleaning products etc. Cacti and succulents, which require less water than other house plants and release less pollen, can be substituted for plants requiring more damp conditions. When mold is a problem indoors, the source of the moisture that led to the fungal growth must be eliminated. Without adequate moisture, the mold will become dormant and will no longer produce spores or the metabolic VOCs (volatile organic compounds) that give it its characteristic odor.

Keep in mind that the air inside HVAC ducts will be breathed by the occupants. Therefore, a duct's interior should be considered living space. So, a tight structure should also mean tight ductwork to prevent pollutants from outside the ducts (e.g. those found in the attic and crawl space) from entering them and ultimately affecting the occupants. It's also important that the interior surface of the ducts not be a source of particles or contamination, so don't use ducts lined with fiberglass that could enter the airstream.