Fresh Air: Rules for Good Indoor Air Quality

Poor indoor air quality is ubiquitous in the U.S., so much so that the Environmental Protection Agency considers it a chief environmental threat. An EPA Office of Research and Development study found levels of about a dozen common organic pollutants to be two to five times higher inside homes than outside, regardless of whether the home was in a rural or industrial area. 

Home improvement professionals are among the best positioned to combat the issue. But if their efforts are going to have any hope of being effective, they’ll need to first identify the culprit and then remember three things: eliminate, isolate, ventilate.

1. Identify the source

Many remodelers think of pollution only as an ambiguous, omnipresent villain, and so never understand how it’s brought into a home, or more importantly, coaxed out of one. 

The first step in improving indoor air quality is learning what diminishes it: moisture, particles, dust, and volatile organic compounds, known as VOCs, which are emitted from everyday items such as paint, carpeting, and household cleaners, in a process called off-gassing. 

2. Eliminate

The second step is physically eliminating those sources. Some VOC sources are products that become a permanent part of the home, like carpeting or particle board. While you may not be able to eliminate VOC’s completely, it makes sense to choose to use low-VOC or non-VOC-producing products whenever possible. Other sources of pollution come from adhesives and solvents that you need during construction. Something as simple as not storing supplies like this indoors on the jobsite can make a difference. 

A full list of items that produce VOCs, as well as information about the chemicals present in various products and materials, is available online from the National Institutes of Health.

3. Isolate 

If a cause of poor indoor air quality can’t be completely eliminated, the next best thing is to quarantine it. This means storing solvents, adhesive, and other off-gassing building materials in airtight containers, or in a ventilated closet or cabinet. Some insulation can create small particles that stay airborne for a long time, so take steps to keep isolate work areas from the rest of the home. This includes dust creating by trimming closed cell spray foam.

4. Ventilate 

Ultimately, the biggest impact a remodeler can make to a home’s long-term indoor air quality is improving the ventilation system, which is often inadequate. This is often an issue at job completion if glues, sealants, and products like spray foam haven’t had sufficient time to fully sure. Remember also that insulation that also air seals a home can significantly reduce air exchanges, which in turn causes buildup of emissions and other pollutants.

Improper airflow can turn humid spots into incubators for mold and mildew as well, which can cause asthma. Stagnant air also keeps harmful dust and particulates in the home instead of flushing them outdoors in exchange for cleaner outside air. 

ASHRAE ventilation standard 62.2 on ventilation and indoor air quality explains exactly how much air needs to be removed from a room to keep humidity levels in range. In a bathroom of less than 50 square feet, for example, it’s a minimum of 50 cubic feet per minute. But many remodelers lean on highly rated, well-tested fans to ensure proper airflow in areas like bathrooms, but for those fans to work properly, the entire assembly has to be installed correctly. That includes the ductwork, which should properly sized and as short and straight as possible, and the termination. 

A poorly designed, damaged, or incorrectly installed wall, roof, or soffit vent cap can greatly stifle airflow. 

If you approach a project keeping the three rules of better indoor air quality top of mind: eliminate, isolate, and ventilate, you should be able to avoid retro-fixes.