Indoor Air Quality Assessment Checklist

What an indoor air quality assessment is

An indoor air quality assessment is a structured walkthrough of a building to understand what occupants are breathing. You inspect the building envelope, the HVAC system, and the spaces in between, then record measurements and observations that describe the conditions on the day. The assessment covers several connected areas: 1. Visual inspection and maintenance 2. Potential pollutant sources 3. Temperature and humidity 4. Air filtration and cleaning 5. Ventilation and air exchange 6. Occupant activities 7. Carbon dioxide levels, where measured It closes with a set of recommendations and action steps. You record each item against a simple scale — **Satisfactory**, **Requires Attention**, or **Not Applicable** — so the final report shows both what was checked and what needs work.

Why it matters

Poor indoor air quality shows up as complaints that are hard to pin down: stuffiness, odours, headaches, or discomfort that occupants link to a particular room or time of day. An assessment turns those vague reports into specific, checkable findings. It matters because most of the causes are manageable once you know where they are. Water intrusion, damp restrooms, and blocked exhausts are physical problems you can fix. Overloaded filters, restricted diffusers, and unbalanced air distribution have straightforward remedies. Identifying pollutant sources and occupant practices gives you a basis for changing what happens in the building, not just how it is ventilated.

What a good assessment covers

A good assessment moves through the building in a logical order and leaves a clear trail from observation to action. - **Building envelope and moisture.** Windows, doors, and wall assemblies checked for cracks, air leakage, and failed sealing. Restrooms, kitchen areas, and utility spaces checked for active mold, condensation, and persistent dampness. - **Pollutant sources.** Chemical cleaning agents, combustion byproducts, tobacco use, cooking emissions, and off-gassing building materials, along with fragrances, candles, incense, and oil diffusion systems. - **Thermal conditions.** Temperature readings across each distinct zone and relative humidity measured with a calibrated hygrometric instrument, compared against ASHRAE Standard 55 comfort parameters. - **Filtration and cleaning.** Filter loading and replacement intervals, the condition of evaporator coils, condensate pans, and ductwork, and the effectiveness of dusting, HEPA-filtered vacuuming, and wet mopping. - **Ventilation.** HVAC operation and air distribution, the condition of supply diffusers, return grilles, and exhaust registers, and the working order of restroom and kitchen exhaust systems. - **Occupant factors.** Activities and processes that may degrade air quality, and occupants' own awareness and daily practices. - **Carbon dioxide, where measured.** Readings taken with a calibrated CO2 monitor and compared against ASHRAE-recommended thresholds, used as an indication of air exchange. A good assessment ends with recommendations that name the specific problem and the specific fix: a filter replacement schedule using appropriate MERV-rated media, relocation of a smoking area, substitution of high-VOC products, remediation of a moisture source, or an occupant education initiative.

How to use the checklist

The checklist is the tool that keeps the walkthrough consistent and produces a record you can act on and revisit. Work through it in order so each section builds on the last. Start with the visual examination of interior areas, then the building envelope and general cleanliness. Move on to pollutant sources and moisture-prone rooms before you take temperature and humidity readings, so you can note anything in the room that affects them. Inside the building, mark each item as **Satisfactory**, **Requires Attention**, or **Not Applicable**. Where an item calls for a measurement, record the reading and the device you used. Where it calls for a comparison, note the reference range, such as ASHRAE Standard 55 for comfort or the ASHRAE-recommended indoor air quality thresholds for CO2. Finish with the Recommendations and Action Steps section. Turn each item marked Requires Attention into a concrete step, and use the additional notes field for anything unusual that needs a second look. Then schedule the follow-up assessment so the actions have a date attached to them.

Frequently Asked Questions

Use a calibrated instrument and record readings across each distinct thermal zone and representative room. Also measure relative humidity with a calibrated hygrometric device, so you can see how conditions vary across the building rather than relying on a single spot reading. You then compare the results against ASHRAE Standard 55 comfort parameters and accepted environmental ranges. Spot measurements taken during extreme outdoor conditions or unusually high or low occupancy are less useful.

Yes. The checklist includes an optional section for measuring carbon dioxide concentrations in ppm with a calibrated CO2 monitoring device and comparing the readings against ASHRAE-recommended indoor air quality thresholds. CO2 is a useful indicator of whether outdoor air is reaching occupied spaces. You should treat it as one signal among several rather than a complete picture of air quality.

The checklist starts with visual walkthroughs and pollutant identification, then moves through temperature and humidity, filtration and cleaning, ventilation and air exchange, and occupant activities. It closes with recommendations and action steps. Work through the area in that order so the findings from the earlier walkthrough feed into your mitigation plan. You record each item as Satisfactory, Requires Attention, or Not Applicable.

It covers building envelope components such as windows, doors, and wall assemblies, plus HVAC components including filters, evaporator coils, condensate drain pans, and supply ductwork. It also addresses custodial cleaning protocols and the operational status of supply and return air distribution. Any issue you mark as Requires Attention should point to a specific item in your mitigation plan, for example filter replacement, moisture remediation, or ventilation improvement.

No. The checklist notes that some items are optional, such as the carbon dioxide monitoring section. You can adapt the scope to the site, for example if the facility has no cooking areas, or the assessment is a follow-up with a narrower focus. Whatever you leave out should be recorded so the report shows what was and was not covered.

Written by

Arne Reis

Founder

Process optimizer with 25 years of expertise, focused on operational excellence in quality, maintenance, EHS, and commissioning. Emphasizes innovative solutions and top-quality standards.

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