Indoor Air Quality 101: What to Measure, What to Ignore

Indoor air quality (IAQ) is real. Bad IAQ measurably affects sleep, cognition, and long-term respiratory health. But most of what's marketed as "IAQ improvement" isn't — it's product-pushing. Here's the honest primer.

The four things that actually matter

1. Particulate matter (PM2.5, PM10). Fine dust, smoke, and combustion particles. Chronic exposure is the biggest health risk. Sources in the Valley: desert dust, wildfire smoke (August–October), traffic, wood-burning fireplaces.
2. Carbon dioxide (CO2). Marker of ventilation. Above 1,000 ppm you start feeling drowsy and stupid; above 1,500 ppm it measurably affects decision-making. Tightly sealed modern homes without ventilation build up CO2 fast.
3. Humidity. Too dry → respiratory irritation. Too humid → mold, dust mites. Target 30–50%.
4. VOCs (volatile organic compounds). Off-gassing from cleaners, paints, glues, new furniture, air fresheners. Usually acute (weeks to months) after installation, but some sources are chronic.

What to measure

A $150–$300 indoor air quality monitor (Awair, Airthings, PurpleAir) gives real-time PM2.5, CO2, humidity, and VOC readings. Better than any anecdote from a sales pitch. Buy one, put it in your primary living space, log a couple of weeks, then decide.

What to actually do

For PM2.5

• MERV 11–13 filter in the HVAC system (see Air Filters & MERV)
• Portable HEPA air purifier in the bedroom during wildfire season
• Seal duct leaks so you're not pulling attic dust into the system

For CO2

• Balanced mechanical ventilation (ERV or HRV) — most Valley homes don't have this yet, but new California code is pushing it
• Open a window when the outdoor air is clean (winter mornings, spring)
• Kitchen exhaust fan vented outdoors — every meal generates CO2 and combustion byproducts

For humidity

See Managing Desert Humidity.

For VOCs

• Ventilate aggressively after painting, new furniture delivery, or major cleaning
• Choose low-VOC / no-VOC products
• Avoid plug-in air fresheners — they're VOC sources, not solutions

What to ignore

• Any device that "generates" ozone (marketed as "activated oxygen"). Ozone is a lung irritant.
• "Whole-home sanitization" claims from UV lights (they sterilize the coil, not the air — see UV vs. Air Purifier).
• Any product that claims to "cure" allergies, asthma, or COVID transmission. Filtration reduces, doesn't eliminate.

Serious IAQ concerns need a properly designed system, not a series of add-ons. If you're worried about your air, book a comfort assessment — we'll measure, tell you what's real, and recommend only what actually helps.