What Is an Indoor Air Quality Improvement Checklist?
An Indoor Air Quality Improvement Checklist is a structured, room-by-room audit of the factors that determine what you actually breathe at home. It walks through 33 specific items across seven categories — ventilation, moisture, filtration, chemical sources, combustion, allergens, and outdoor intrusion — scores your home against each, and ranks the unresolved items by how much they matter. Most people focus on the visible (dust, smell, a purifier) and miss the invisible (mold behind a cabinet, an exhaust hood that recirculates instead of venting, a gas stove without a working hood, a missing CO detector). This tool surfaces all of it.
Indoor Air Quality Improvement Checklist
Work through 33 specific, room-by-room items that determine what you actually breathe at home. Score your home, see exactly which unresolved items matter most, and get a clear, ordered priority list — not a vague "improve ventilation".
Your Home Audit
Air Quality Report
Work through the checklist on the left. Your score, category breakdown and priority list will appear here as you tick items off.
Saved Audits
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Introduction: What Is an Indoor Air Quality Improvement Checklist?
An Indoor Air Quality Improvement Checklist is a structured, room-by-room audit of the factors that determine what you actually breathe inside your home. It works through 33 specific items across seven categories — ventilation, moisture and mold, filtration and cleaning, chemical and fragrance sources, combustion and carbon monoxide, allergens and pets, and outdoor intrusion — scores your home against each, and ranks the unresolved items by how much they actually matter.
Most people focus on the visible aspects of indoor air: dust on a shelf, a smell in the kitchen, a purifier they can point to. The biggest problems are almost always invisible. A range hood that recirculates instead of venting. A bathroom exhaust that dumps warm moist air into the attic rather than outside. A gas stove used daily without a working hood. Mold behind a cabinet or under a bathroom sink. A missing carbon monoxide detector on the second floor. A radon level that has never been tested. None of these are visible from the room, and none show up on a purifier's filter. They are the actual IAQ story.
The evidence on indoor air is unusually clear. Indoor pollutant concentrations are typically two to five times higher than outdoor concentrations, sometimes far more during specific events. Most people spend 90% of their time indoors, so the indoor exposure dominates. And most of the serious risks — carbon monoxide from combustion, mold and moisture problems, radon, unvented gas appliances — are entirely preventable with specific, well-understood fixes that cost less than most people assume.
This free indoor air quality checklist is designed for practical use. It gives you 33 specific items, each with a real explanation of why it matters, an impact rating (1–5), an effort estimate (quick, medium, project), and a cost range (free, low, medium, high). As you check items off, your score updates live, the priority list reorders itself to show what matters most, and the report tells you exactly how many high-impact items are still unchecked, how many free fixes are available, and what remains to be done for asthma, children, older adults, pets, or a smoker in the home.
It also goes beyond a simple checklist in two ways. First, it handles "not applicable" items properly — if you don't have a fireplace, that item isn't counted against you. Second, it adjusts the priority ranking based on household sensitivities. If there's an asthmatic in the home, ventilation, moisture and allergen items rise to the top of the list. If there's a child under 5, combustion and CO items get the strongest weighting. The priority order is not a single list — it is the right list for your household.
Key Takeaways
- Indoor air is typically 2–5× more polluted than outdoor air — and we spend 90% of our time indoors.
- The biggest IAQ risks are invisible: recirculating hoods, hidden mold, missing CO detectors, untested radon.
- Ventilation is the foundation — a purifier cannot fix a home with no fresh-air exchange.
- Combustion sources (gas stoves, fireplaces, heaters) are the highest-severity risk category because of CO and NO₂.
- Moisture problems cause mold and dust mites — the two most common indoor allergen sources.
- Radon is the leading cause of lung cancer after smoking, and it is completely testable and fixable.
- Fragrance and cleaning products are underestimated sources of VOCs, especially in small or sealed rooms.
- Most of the highest-impact fixes are free or under $50 — window opening, filter changes, CO detectors, unplugging air fresheners.
- The biggest-cost items (venting a hood, sealing a crawlspace, radon mitigation) are usually the ones with the greatest long-term impact.
- Household sensitivities change priorities — an asthma diagnosis should rearrange your list.
Features of This Indoor Air Quality Checklist
1. 33 Specific Items Across 7 Categories
Ventilation (5 items), moisture and mold (5), filtration and cleaning (5), chemical and fragrance sources (5), combustion and CO (5), allergens and pets (4), and outdoor and radon (4). Each item is a specific, actionable check — not a vague instruction. "Kitchen exhaust hood vents to the outdoors" rather than "improve ventilation".
2. Impact, Effort and Cost on Every Item
Every item is tagged with an impact rating (1–5), an effort level (quick, medium, or project), and a cost range (free, low, medium, high). This lets you scan the list for the high-impact, quick, free fixes — and see clearly which items are genuinely worth the effort of a weekend project.
3. Live Scoring
Your score is computed as the weighted completion percentage — the sum of impact weights for completed items divided by the sum of impact weights for applicable items. This means fixing a high-impact item (like installing a CO detector) raises your score much more than fixing a minor one (like adding a doormat). The score updates in real time.
4. Priority-Ranked Remaining Items
The report shows a priority list of the top unresolved items, sorted by impact × household sensitivity. If there is an asthmatic in the home, ventilation and allergen items rise to the top. If there is a child under 5, combustion items get the strongest weighting. The list is personalized, not generic.
5. Not-Applicable Handling
Each item can be marked "not applicable" with a small N/A toggle. If you don't have a fireplace, no pets, or already had radon tested, that item is removed from the scoring denominator rather than counted against you. This keeps the score honest for homes that genuinely differ.
6. Category-by-Category Breakdown
A bar chart shows your completion within each of the seven categories, so you can see where the largest gaps are. Typically people score well on visible items (cleaning, filtration) and poorly on invisible ones (venting, moisture, radon). The breakdown makes that pattern obvious.
7. Household Sensitivity Profiles
Six optional profiles — asthma/allergy, child under 5, older adult, pets indoors, smoker at home, pregnant — that adjust the priority ranking and raise specific flags. Selecting "child under 5" prioritizes CO detectors, unvented heaters and radon testing. Selecting "asthma" prioritizes ventilation, moisture and allergen items.
8. Realistic Cost and Effort Estimates
Each item shows whether it is a quick fix (under 30 minutes), a medium-effort task (30 min to 2 hours), or a project (weekend or hire a professional). Cost is shown as a range: free, under $50, $50–300, or over $300. This is not a budget tool, but it is honest about the real effort involved.
9. Live Category Progress
The tabs show a live count of how many items are still unresolved in each category, and a checkmark when the entire category is complete. The overall progress bar and item counter at the top of the checklist update as you work.
10. Priority List With Reasons
Each prioritized item in the report shows its title, its specific fix, its impact/effort/cost tags, and the reason it was prioritized (which profile triggered it, or why it is broadly high-impact). This is the difference between a checklist and a plan.
11. Save, Compare and Print
Save any audit with its date, score, items complete and critical remaining count. Print the report as a reference sheet with the score, the priority list and the category breakdown. Useful for landlords, home inspectors, and anyone who is improving a home slowly over time.
12. Fully Private
No account, no uploads, no tracking. Everything runs in your browser and saved audits are stored in local storage only.
How to Use the Indoor Air Quality Checklist
- Start with the household profile. Tick any of the six chips that apply — asthma, child under 5, older adult, pets indoors, smoker, pregnant. This adjusts the priority ranking and raises specific flags later in the report. It does not change the raw score, only the order in which fixes are recommended.
- Work through the categories in order. Ventilation first, then moisture, then filtration, then chemical, then combustion, then allergens, then outdoor. This is not arbitrary — it reflects the impact hierarchy. Ventilation is the foundation; without it, everything else is diminished. Combustion and moisture are the highest-severity categories, but they matter only if ventilation is not actively introducing problems.
- Be honest about the check. "Kitchen exhaust vents outdoors" means the duct actually goes to the exterior — not that a hood exists. A recirculating hood is not vented. If you are not sure, mark it unchecked until you verify.
- Use "not applicable" for items that genuinely do not apply. No fireplace, no pets, already tested radon, no attached garage — mark N/A. This keeps your score honest rather than artificially low.
- Do not tick "done" unless the fix is genuinely complete. A CO detector with a dead battery is not a done item. An HVAC filter that is due in two weeks is not a done item.
- Look at the priority list in the report. It shows the top unresolved items, ranked by impact and by household sensitivity. The top three are the ones worth doing this week.
- Check the free-fix count. The stats row shows how many free fixes are still available. Most people find 4–8 — window opening, unplugging air fresheners, shoes at the door, verifying CO detectors. These are worth doing first, because they cost nothing and often have real impact.
- Read the flags. Each profile raises specific flags — combustion items for households with children, allergen items with pets, CO and radon for older adults. Each flag comes with the specific reason and what to do.
- Save the audit. Then revisit it in a month, after doing the top few items. The comparison is the most useful data you will get — it shows whether your improvements actually moved the score.
- Repeat the audit annually. Homes change: appliances age, weather sealing degrades, filters get forgotten, and radon should be retested after major renovations. An annual pass takes 15 minutes and keeps the score honest.
Pro tip: Do not try to do everything at once. The highest-impact items — venting the kitchen hood, testing for radon, installing CO detectors on every floor, verifying that the bathroom exhaust actually vents outside — are usually project-level items that take a weekend each. Pick the one that affects your household most (based on the profile flags) and do it this month. Save the quick free fixes for the same day. Within three months, you will have moved your score from the 30s or 40s into the 70s or 80s, and you will have addressed the items that actually matter.
Who Can Use This Indoor Air Quality Checklist?
This home IAQ audit tool is built for anyone who wants to understand and improve what they breathe at home:
- Anyone who has just moved into a new home and wants a systematic way to check it.
- Parents of young children who want to reduce the specific risks that matter for developing lungs.
- Anyone with asthma, allergies or COPD who needs a structured approach rather than random improvements.
- Older adults for whom CO, radon and combustion risks are more consequential.
- Pregnant women who want to reduce exposure during a period when air quality matters more.
- Pet owners dealing with dander and odour, who need to know the allergen-specific fixes.
- Anyone with a gas stove who wants to know whether their kitchen ventilation is actually adequate.
- Renters who need to know which fixes are worth asking the landlord for.
- Homeowners planning renovations who want to build IAQ improvements into the project.
- Landlords and property managers who need a defensible checklist for their units.
- Home inspectors and real estate agents who want a free reference tool for clients.
- Anyone who has experienced a mold or moisture problem and wants to prevent recurrence.
- People who have already bought an air purifier and want to know whether the rest of the home supports it.
Important: this checklist is an educational tool, not a professional inspection. It identifies common issues and prioritizes fixes based on published guidance, but it does not substitute for a licensed home inspector, an HVAC technician, a radon professional, or a mold remediation specialist. If you suspect mold behind walls, a gas leak, a CO problem, or high radon, do not use this tool as your assessment — call a qualified professional. If anyone in the household is experiencing symptoms (headache, dizziness, breathing difficulty, unexplained fatigue) that may be linked to indoor air, stop and seek medical advice.
Why Indoor Air Quality Matters More Than You Think
Indoor Air Is Usually Worse Than Outdoor Air
Studies consistently find indoor pollutant concentrations two to five times higher than outdoor concentrations, and sometimes much more during specific activities — cooking with gas, using cleaning products, running a fireplace, or during high outdoor pollution events when windows are closed. Because the average person spends about 90% of their time indoors, the indoor exposure dominates total exposure even when the outdoor concentration is higher during the moment you step outside.
This is why "I live in a city with bad air" is less useful than "I have good or bad indoor air". The outdoor number is one input; the indoor environment is where most of the exposure actually happens.
The Invisible Categories Are the Highest-Severity Ones
Combustion is the highest-severity category because carbon monoxide is odourless and can be fatal. A gas stove used without a working hood, an unvented space heater, a blocked chimney, or a vehicle idling in an attached garage can all produce dangerous CO levels in a home without any obvious warning. This is why CO detectors on every floor are non-negotiable — they are the only way to know.
Moisture is the second-highest because it drives mold growth and dust mites, which are among the most common and most impactful indoor allergens. Mold behind a cabinet, under a bathroom sink, or in a damp basement can produce spores that circulate through the home for months before anything visible appears. The check is often quick (look for discoloration, check for a musty smell), but the remediation can be significant if the source is not addressed.
Radon is the third because it is a leading cause of lung cancer after smoking and is present at dangerous levels in a significant fraction of homes in many regions — and it has no smell, no colour, and no visible sign. The only way to know is to test, and the test is cheap and easy.
Ventilation Is the Foundation, Not a Nice-to-Have
No amount of filtration fixes a home that does not exchange air with the outdoors. A HEPA filter will remove particles from the air that passes through it, but if the air is not being refreshed, the concentration of everything that is not filtered — VOCs, CO₂, moisture, and gases — climbs. Modern, tightly sealed homes with excellent insulation have a specific IAQ problem: they are very efficient at keeping air inside, which means pollutants also stay inside.
The single most important IAQ habit is regular air exchange — opening windows for ten minutes a day, or using a mechanical ventilation system if the home has one. Everything else in the checklist works better when that is in place.
The Categories People Underestimate
Two categories are systematically underestimated. First, fragrance and cleaning products. Scented candles, plug-in air fresheners, laundry detergents with strong fragrance, and many cleaning products are significant sources of VOCs and secondary organic aerosols. Studies have shown that some scented candles can produce particle concentrations comparable to a running diesel engine, and that fragrance products emit a wide range of compounds that are not always captured on ingredient lists. Removing scented candles and switching to fragrance-free cleaning is a genuine IAQ improvement, not a fringe preference.
Second, radon testing. Most homes have never been tested, and most people have no idea what their level is. Testing is inexpensive (often under $30 for a short-term test kit, sometimes free from local health departments), and if the level is elevated, mitigation is a well-established process that typically runs $1,000–$3,000. This is one of the highest-return items on the entire list, and it is routinely skipped.
The Visible Fixes Are Useful but Rarely Sufficient
Buying a HEPA purifier, changing the HVAC filter, and vacuuming more often are all good IAQ improvements. But they address particles, not gases, not moisture, not combustion, and not the source-level problems that keep producing pollutants. A home with a recirculating range hood, a musty basement, and no CO detectors can score well on the "visible" fixes and still have significant underlying problems.
The checklist is designed to counteract this bias. Ventilation and combustion items come first, moisture comes early, and the report's priority list is weighted to push you toward the invisible categories rather than the easy ones.
What a Checklist Can and Cannot Do
It can surface the specific, well-known issues that most homes have, prioritize them honestly, and tell you what each fix involves. It can help you decide which fixes are worth doing this month and which can wait. It can make the invisible visible in a way that reading general advice cannot.
It cannot diagnose. It cannot detect a slow gas leak, measure your actual CO level, test your radon, or identify mold behind a wall. For those, you need a professional and a measurement. The checklist's job is to tell you which measurements are worth taking — CO, radon, and a proper HVAC inspection are the three most worth doing if you have not done them recently.
Conclusion
Indoor air quality is one of the few environmental health factors you can meaningfully improve — but only if you know which specific problems your home actually has. The visible fixes (a purifier, a filter change, more vacuuming) are useful but rarely sufficient. The invisible ones — recirculating hoods, hidden moisture, missing CO detectors, untested radon, unvented gas cooking — are where the real risks live, and they are where most homes have their largest gaps.
Use this free Indoor Air Quality Improvement Checklist to work through the 33 items systematically. Set your household profile, tick what is already done, mark the ones that do not apply, and read the priority list. The free fixes come first — they often involve verifying or changing something you have never actually checked. The high-impact projects come next, prioritized by what actually matters for your household.
Do not try to finish the checklist in one sitting. Do it in three passes: the free items this weekend, the medium-effort items over the next month, and the project items over the next six months, starting with the one that most affects your family. At the end of each pass, re-score — and the numbers will show you what you actually changed. That feedback loop is what makes a checklist into a real improvement, rather than a list you read once and forgot.
Frequently Asked Questions
What are the most important indoor air quality improvements?
In order of impact for most homes: (1) working carbon monoxide detectors on every floor, (2) proper kitchen ventilation that vents outdoors, (3) addressing any moisture or mold problems, (4) testing for radon, (5) not using unvented gas or kerosene heaters indoors, (6) regular air exchange through windows or mechanical ventilation, (7) keeping indoor humidity between 30% and 50%, and (8) using a MERV 11+ HVAC filter changed on schedule. These overlap heavily with the top items on this checklist.
How often should I change my HVAC filter?
For most homes, every 1–3 months. Change it more often if you have pets, if anyone in the home has allergies or asthma, if you live in a dusty area, or if the filter is a high-MERV type (MERV 13+ filters can restrict airflow and load faster). Change it less often only if the home is rarely occupied and the filter is visibly clean when checked. A good rule: check it monthly, change it when it looks visibly grey.
Does a range hood actually help indoor air quality?
Yes — but only if it actually vents outdoors. A recirculating hood, which passes air through a filter and blows it back into the kitchen, removes some visible smoke and odour but leaves the NO₂, CO, fine particles and moisture in the room. A properly ducted hood removes all of those. If your hood is recirculating and you cook with gas, this is one of the highest-impact upgrades you can make. If you cannot duct, an alternative is to switch to electric cooking.
How often should I open my windows?
At least once a day for five to ten minutes is a good minimum. The purpose is air exchange — replacing indoor air with fresh air — which reduces CO₂, VOCs, moisture and any accumulated pollutants. Ten minutes in the morning and ten in the evening is often enough for a typical home. If you live in an area with high outdoor pollution, open windows during cleaner times of day (usually early morning or late evening) and use a HEPA purifier when outdoor air is bad.
Do air purifiers actually improve indoor air quality?
Yes, for particles. A HEPA purifier sized correctly for the room removes a significant fraction of PM2.5, dust, pollen and pet dander. It does not remove CO, NO₂, radon, or most VOCs (unless it has substantial activated carbon). A purifier is a complement to — not a replacement for — ventilation, source control and moisture management. If a home has a combustion problem, a purifier does not solve it; you need ventilation or source removal.
What is a safe indoor humidity level?
30% to 50% relative humidity is the standard range. Below 30% is too dry (irritates airways, worsens eczema and static), and above 50% favours dust mites and mold. Above 60% is a mold risk. You can measure with a cheap hygrometer (under $20) placed in the main living area and the bedroom. In humid climates or basements, a dehumidifier is often necessary. In very dry climates or during winter, a humidifier (kept clean) may be needed.
How do I test my home for radon?
Radon test kits are inexpensive (usually $20–$40 from hardware stores or online) and are also often available free from local health departments. Short-term test kits (2–7 days) give a quick read; long-term kits (3–12 months) are more accurate. Place the test in the lowest livable level of the home, closed-house conditions. If the result is 4 pCi/L or higher, consider mitigation — a well-established process that typically costs $1,000–$3,000 and typically includes ventilation under the foundation. Retest after any major renovation.
Are scented candles and air fresheners bad for indoor air?
They are underestimated sources of VOCs and fine particles. Studies have found that some scented candles and plug-in air fresheners produce measurable increases in particle concentrations, formaldehyde, and a wide range of fragrance compounds, some of which are known respiratory irritants. The IAQ field generally recommends eliminating them in homes with asthma, allergies, or young children. If you use candles, ventilation during and after burning helps — but the cleanest option is fragrance-free or no added scent.
What is the biggest source of indoor air pollution?
It depends on the home. The biggest single-source risks are combustion (gas stoves, fireplaces, unvented heaters, attached garages), moisture and mold, and radon. On a chronic exposure basis, cooking, cleaning products, and off-gassing furniture and building materials are significant sources of VOCs and particles. The most common single problem in most homes is inadequate ventilation — the home does not exchange enough air with the outdoors — which amplifies every source.
How can I improve indoor air quality cheaply?
The highest-value free or cheap fixes: (1) install carbon monoxide detectors on every floor ($20–$30 each), (2) open windows for 10 minutes twice a day, (3) change the HVAC filter on schedule, (4) unplug air fresheners and stop using scented candles, (5) fix visible moisture problems and run bathroom exhaust fans, (6) switch to fragrance-free cleaning products, (7) remove shoes at the door, (8) test for radon ($20–$40). Together these cost less than $150 and address many of the highest-impact items on this checklist.
Do houseplants improve indoor air quality?
Barely. While houseplants do remove some VOCs in laboratory studies, the effect in a real home is negligible — you would need hundreds of plants per room to meaningfully improve air quality, and the soil itself can be a source of mold spores. Houseplants are lovely to have, but they are not an IAQ strategy. Ventilation and source control do far more.
Is this indoor air quality checklist free and private?
Yes. The tool is completely free, requires no sign-up or account, and runs entirely in your browser. Saved audits are stored in your browser's local storage. No data is transmitted to any server, and you can clear everything at any time with one button.
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