Indoor Air Quality 101: What the Numbers Actually Mean (And What's Normal)

You've heard that indoor air quality matters. You've perhaps seen a monitor displaying numbers like "CO₂: 1,247 ppm" or "Humidity: 63%." But what do those numbers actually mean? Are they alarming? Acceptable? And what should you do when they're outside a certain range?

This guide is a plain-English reference for understanding every number your air quality monitor might show — so you can move from passive data collection to confident, informed action.

CO₂ (Carbon Dioxide) — Measured in Parts Per Million (ppm)

CO₂ is produced by human respiration, combustion (gas stoves, candles, fireplaces), and even fermentation. In outdoor air, it currently sits at approximately 420 ppm. Indoors, it accumulates without ventilation.

CO₂ Level Assessment What You Might Feel
400–600 ppm Excellent ✅ Alert, energized, clear thinking
600–1,000 ppm Good 🟡 Normal, no significant impact for most people
1,000–1,500 ppm Moderate ⚠️ Mild fatigue, slight difficulty concentrating; sensitive individuals affected
1,500–2,500 ppm Poor 🔴 Headaches, significant brain fog, fatigue, poor decision-making
2,500–5,000 ppm Very Poor ❌ Drowsiness, poor concentration, increased heart rate, cognitive impairment
Above 5,000 ppm Dangerous 🚨 OSHA workplace limit; dizziness, nausea, shortness of breath

What action to take: If CO₂ rises above 1,000 ppm, increase ventilation. Open a window, door, or run a fresh-air ventilation system. Levels typically drop to 600–700 ppm within 10–15 minutes of adequate ventilation.

Relative Humidity (RH) — Measured in %

Relative humidity measures the amount of water vapor in the air as a percentage of the maximum it can hold at that temperature. It directly affects comfort, health, and your home's structural integrity.

Humidity Level Assessment Concern
Below 25% Too Dry ❌ Dry skin, static, increased virus survival, cracking wood
25–40% Low ⚠️ Mild dryness, some discomfort, increased susceptibility to respiratory illness
40–60% Ideal ✅ Optimal comfort, minimal allergen and pathogen activity
60–70% High ⚠️ Mold risk increases, dust mites proliferate, feeling clammy
Above 70% Too Humid ❌ Active mold growth, structural damage risk, significant allergen exposure

What action to take: Below 40%? Use a humidifier. Above 60%? Use a dehumidifier, improve ventilation, or use air conditioning. Focus on the bathroom, kitchen, and basement as primary humidity sources.

Temperature — Measured in °C or °F

Indoor temperature affects everything from comfort and sleep to metabolism and cognition. The "right" temperature varies by time of day and activity:

  • Sleep: 16–19°C (60–67°F) — cooler temperatures support deeper, more restorative sleep
  • Focused work: 20–22°C (68–72°F) — research finds this optimal for sustained attention
  • General daytime comfort: 20–23°C (68–73°F)
  • Children and elderly: slightly warmer, typically 21–23°C (70–73°F)

How to Read Your Monitor — A Quick Decision Framework

If you own the Aeris View or another CO₂/humidity/temperature monitor, here's a simple daily routine:

  1. 1. Morning check: Look at overnight CO₂ peak (shown in trend history). If it exceeded 1,500 ppm, your bedroom needs better overnight ventilation.
  2. 2. Work session check: Monitor CO₂ every 30–60 minutes. If it climbs above 1,000 ppm, open a window before your focus drops.
  3. 3. Evening humidity check: After cooking and bathing, check that humidity hasn't spiked above 65%. Run the exhaust fan longer if needed.
  4. 4. Seasonal temperature check: In winter, confirm bedroom temperature is in the 17–19°C range for optimal sleep. In summer, confirm home office isn't drifting above 23°C.

The Numbers Are Just the Beginning

Understanding these numbers is the first step. The second — and more powerful — step is building the habits that respond to them automatically. Once you've spent a few weeks glancing at your monitor throughout the day, you develop an intuition for when to open a window, when to run the humidifier, and when to nudge the thermostat. The data becomes behavioral change. The behavioral change becomes better health.

That's the real value of air quality monitoring: not the device itself, but the awareness it creates over time.

Explore the Aeris View monitor →

Free shipping across Canada • Founder Guarantee • Know your air

0 comments

Leave a comment