Indoor Air Quality (IAQ)

How clean and healthy the air is inside a building.

Quick Answer

Indoor air quality (IAQ) is the condition of the air inside and around buildings as it relates to the health and comfort of occupants. It is shaped by ventilation, filtration, humidity, material emissions, and pollutant sources. Poor IAQ is linked to discomfort and health symptoms, so it is managed through design, construction, and operations.

The Full Picture

People spend most of their time indoors, so the air inside buildings has a direct effect on health, comfort, and productivity. The U.S. EPA notes that indoor concentrations of some pollutants can be higher than outdoor levels, which is why IAQ is treated as a building performance issue rather than a comfort extra.

IAQ is driven by a handful of mechanisms: pollutant sources such as volatile organic compounds from finishes, combustion products, radon, and moisture-related mold; the ventilation rate that dilutes them; filtration that removes particles; and humidity and temperature control. ASHRAE Standard 62.1 sets ventilation requirements for commercial buildings, and building codes typically reference it.

On the jobsite, IAQ is largely about sequencing and protection. Teams seal ductwork during construction, protect absorptive materials from moisture, keep dust away from installed systems, and in many certification programs run a flush-out or testing before occupancy. Low-emitting product selection is a specification-stage decision that is hard to reverse later.

IAQ problems tend to appear after turnover as occupant complaints, so they are expensive to trace. Good practice looks like source control in the specifications, right-sized ventilation, accessible filters, moisture management in the envelope, and commissioning that confirms airflows. Poor practice treats the HVAC system as the only fix for contaminants that could have been avoided at the source.

Real Examples

→Low-emitting finishes: The specification requires paints, adhesives, and flooring that meet recognized low-VOC emissions criteria, reducing contaminant load at occupancy.

→Duct protection: During construction, the contractor caps open duct ends and stores insulation off the slab so dust and moisture don't enter the air distribution system.

→Pre-occupancy flush-out: Before move-in, the team runs the ventilation system at high outdoor air rates to clear residual construction emissions from a new office floor.

Common Misconceptions

People assume: Indoor air is cleaner than outdoor air.

Actually: Not necessarily. EPA reports that indoor levels of some pollutants can exceed outdoor levels, because sources are enclosed and ventilation may be limited.

People assume: Opening up ventilation fixes any IAQ problem.

Actually: Dilution helps, but it won't solve moisture, mold, or strong emission sources, and it costs energy. Source control and moisture management come first.

Frequently Asked Questions

What is indoor air quality?

IAQ is the quality of air inside buildings with respect to occupant health and comfort. It reflects pollutants, ventilation, filtration, humidity, and temperature.

What affects IAQ in a new building?

Emissions from building materials and finishes, the ventilation rate, filter quality, moisture control, and how well the HVAC system was protected and commissioned all contribute.

Which standard governs ventilation for IAQ?

ASHRAE Standard 62.1 covers ventilation for acceptable indoor air quality in most commercial buildings, and the model codes often reference it.

How is IAQ tested?

Methods include measuring ventilation rates, particulate and CO2 levels, and sampling specific contaminants such as formaldehyde or VOCs. The scope depends on the project's requirements.