Quick answer
Read in 4 minIndoor Air Quality is not a single number — it is a small dashboard of measurements that together describe what your family is breathing. The honest list is five things: particulate matter (PM2.5 and PM10), volatile organic compounds (VOCs), carbon monoxide (CO), carbon dioxide (CO2) as a proxy for fresh-air dilution, and humidity. The EPA's research showing indoor air is often 2–5 times more polluted than outdoor air is real and worth taking seriously, but it does not mean every house needs a $10,000 IAQ overhaul. It means you should measure first, then fix what the numbers actually say is wrong. We do this work in Newburgh and Evansville homes every week and the fix is almost never the gadget the homeowner thought they needed.
- 01 PM2.5 target: below 12 µg/m³ indoors (matches EPA outdoor standard).
- 02 CO2 target: below 1,000 ppm — above that means you need more fresh-air ventilation.
- 03 VOCs: highest right after new paint, flooring, or furniture; off-gas weeks to months.
- 04 Carbon monoxide: anything above 9 ppm sustained needs investigation; 70+ ppm is dangerous.
- 05 Real IAQ testing measures all five — not just "particles" or just "VOC".
Section 02
When you actually need an IAQ assessment
If someone in the household has new-onset allergies, asthma symptoms that worsen indoors, persistent headaches, sleep that won't restore, or unexplained respiratory irritation, an IAQ assessment is worth doing. So is the year after major renovation, new flooring, or a new attached-garage car. Most of the SW Indiana homes we test fall into one of three buckets: fine and the symptoms are not IAQ; humidity-driven with a mold or moisture component; or combustion-related with a CO trickle from a misadjusted furnace or water heater. The honest answer almost always comes from the measurements, not the gut feel.
Section 03
What we actually find in Ohio Valley homes
The most common finding is high RH driving high PM2.5 from biological sources — dust mite waste and mold spore fragments. Second most common is high VOC from recent flooring or paint that hasn't finished off-gassing. Third is low fresh-air exchange — CO2 climbing into the 1,500-2,500 ppm range during sleep, which is enough to wreck sleep quality and concentrate every other pollutant in the house. Outright dangerous CO is rare but we have found it — usually a flue problem on an older furnace or an unvented gas appliance — and that's a call we make immediately.
Section 04
When the symptom is real but the source isn't the air
Sometimes we test and the air is fine. That is a useful answer — it points the family back to their doctor or allergist with data instead of guesses. We have walked away from "sell me an air purifier" jobs because the measurements said the house was clean and the homeowner deserved an honest "you don't need this." That is the call we would make for our own basement and it is the call we make for yours.
Section 05
When to test versus when to just fix
If you smell a clear musty odor in the basement, you don't need a test to know there's moisture — fix the moisture. If your CO detector chirps, you don't need a VOC count — find the combustion source. Testing is most valuable when the symptoms are vague and the source is unclear. It is also the only honest way to prove a fix worked, which is why we measure before and after any major IAQ work.
How it works
The mechanism, explained.
Particulate matter — PM2.5 and PM10
PM2.5 is anything under 2.5 microns — small enough to bypass the upper airway and lodge in lung tissue. PM10 is anything under 10 microns, mostly trapped in nose and throat but still irritating. Indoor sources include cooking (especially gas stoves), candles, fireplaces, smoking, pet dander, dust mite fragments, mold spore fragments, and outdoor air leaking in during high-pollution events. A reasonable target is below 12 µg/m³ for PM2.5 — same as the EPA outdoor annual standard. We've measured 80+ µg/m³ in kitchens during stovetop cooking with no range hood.
VOCs — the off-gassing problem
Volatile organic compounds are carbon-based molecules that evaporate at room temperature. Sources include paint, varnish, particleboard, vinyl flooring, new carpet, cleaning products, air fresheners, and personal care products. Formaldehyde is the big one — it's a known carcinogen and most engineered wood off-gasses it for months. VOC sensors measure total VOC (tVOC) as a proxy. Ventilation dilutes VOCs faster than any filter does; carbon media helps a little. The honest advice for a new build or remodel is to ventilate aggressively for the first 6-12 months.
CO2 — the proxy for fresh-air exchange
Outdoor CO2 is around 420 ppm. Indoor CO2 climbs because people exhale it, and how fast it climbs tells you how tight the house is. Above 1,000 ppm cognitive performance starts dropping; above 2,000 ppm sleep quality is measurably worse. A tight new build with no mechanical ventilation will hit 2,500+ ppm in a closed bedroom by morning. CO2 itself isn't dangerous at residential levels, but if it's high, everything else (VOCs, PM, humidity) is concentrating too. The fix is mechanical ventilation — an ERV or HRV.
Carbon monoxide — the one that kills
CO is invisible, odorless, and produced by incomplete combustion. Properly vented gas furnaces, water heaters, and stoves should put zero CO into the living space. Above 9 ppm sustained is worth investigating; 35+ ppm causes headaches and nausea over hours; 200+ ppm causes acute symptoms quickly; 800+ ppm is rapidly lethal. Every house in SW Indiana with gas appliances needs working CO detectors on every level, period. We test combustion safety on every furnace tune-up and have caught CO leaks in homes the family never knew were leaking.
Key terms in context
Vocabulary you'll see on a real estimate.
This guide is written for indoor air & comfort decisions in Southwest Indiana. It uses the same terminology you'll hear from techs, inspectors, and the permit office.
Failure mode 01
Buying gadgets to fix the wrong problem
The IAQ industry sells a lot of gadgets — UV lights, ionizers, ozone generators, "air purifiers" that are just MERV 11 filters with branding. If you buy a $1,500 air purifier when the actual problem is a moldy crawlspace or a leaking flue, you spent money and didn't solve anything. Worse, ozone generators are actively harmful — ozone is a lung irritant and the EPA has been clear that residential ozone generators do more harm than good. Measure first, fix the source, then add the gadget only if measurements say it's needed.
Failure mode 02
Ignoring the combustion-safety check
We do not get called to enough preventive combustion-safety checks. Furnace heat exchangers crack, water heater flues block with bird nests, dryer vents collapse — and any one of those can dump CO into a basement quietly. The CO detector on the wall is the last line of defense, not the first. A proper combustion analysis on every furnace tune-up takes ten minutes and we have found single-digit CO leaks that the homeowner had been breathing for years before symptoms became clear. Don't skip the annual tune-up.
Proof, process & local validation
- 01 Perfect Climate runs a calibrated combustion analyzer on every gas-appliance tune-up — CO ppm, draft, O2, all recorded.
- 02 We will tell you when measurements say your air is fine — and walk away from the sale. That's the deal.
- 03 15+ years of IAQ work across Vanderburgh, Gibson, Posey, and Warrick counties.
How we build this guidance
- Perfect Climate uses calibrated air quality monitors (PM, VOC, CO, CO2, RH) on every IAQ assessment.
- We coordinate with local environmental testing for suspected mold or radon — not every problem is HVAC.
- 15+ years measuring before recommending — Pat will not sell you equipment you don't need.
Methodology · Perfect Climate uses calibrated PM, VOC, CO, CO2, and combustion analyzers on every IAQ assessment, with measurements recorded before and after any intervention to prove the fix worked.
Last updated 2026-06-24
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Common questions
Questions, answered.
01 How much does an IAQ assessment cost?
Our basic IAQ assessment runs $149-249 depending on the home and what we're testing for. It includes calibrated PM2.5, VOC, CO, CO2, temperature, and RH measurements at multiple locations, plus a combustion analysis on every gas appliance. You get the actual numbers, not a "we recommend equipment" pitch. If the numbers say you don't need anything, we'll tell you that.
02 Are those plug-in IAQ monitors accurate?
The consumer ones (Airthings, Awair, etc.) are roughly correct for trends but not lab-grade. They're useful for spotting patterns — does CO2 spike when the bedroom door closes, does PM2.5 spike when you cook — but the absolute numbers can be off 20-30%. For a one-time professional assessment we use calibrated equipment that's been bench-checked recently. For ongoing awareness in the home, a consumer monitor is fine.
03 Do air purifiers actually help?
It depends on the problem. For PM2.5 in a single room (allergy bedroom, smoke event), a good HEPA portable in the right size is effective and measurable. For VOCs, only carbon-media units do anything and they need constant media replacement. For "general air quality" in a whole house, almost always you get more bang for the dollar from a media filter upgrade and an ERV than from a portable purifier. Ionizers and ozone generators we recommend against, period.
04 Should I worry about radon?
Yes — Southwest Indiana has elevated radon zones and the only way to know is to test. We don't do radon mitigation directly but we work with local mitigation specialists and will refer you. A simple short-term radon test kit from a hardware store is a reasonable first step; if it's elevated, follow up with a long-term test and then mitigation if needed.
05 What's the single best IAQ upgrade for most homes?
If we had to pick one for an average Ohio Valley home, it's a 4-5 inch MERV 13 media cabinet paired with humidity control to keep RH at 45-55%. Those two together solve most of the symptomatic IAQ complaints we see. Adding UV on the coil and an ERV becomes relevant for tighter homes or specific symptoms — but media filtration and humidity are the foundation.
