Air Quality Science (Part III): Formaldehyde & TVOCs — The Invisible Indoor Hazards
When we think of air pollution, outdoor smog, exhaust, and industry usually come to mind. Yet, the air indoors — where we spend over 70% of our time — can be just as harmful, and often more persistent. Two of the most concerning pollutants are Formaldehyde (HCHO) and Total Volatile Organic Compounds (TVOCs).
1. Formaldehyde (HCHO): A Proven Human Carcinogen
● Sources: Engineered wood products, adhesives, paints, coatings, textiles, and even some household goods.
● Release patterns: Can last 3–15 years; higher temperature and humidity accelerate emissions.
● Health effects: Short-term exposure causes eye irritation, throat burning, coughing, and breathing difficulty. Long-term exposure has been linked to nasopharyngeal cancer and leukemia, leading the International Agency for Research on Cancer (IARC) to classify it as a Group 1 carcinogen in 2004.
● Safe threshold: WHO recommends ≤0.1 mg/m³.
Practical actions:
● Choose low-emission materials (E0/E1 grade), certified “formaldehyde-free” furniture.
● Ventilate newly renovated rooms for months before moving in.
● Use air purifiers with activated carbon filters.
● Keep indoor temperature and humidity moderate to slow off-gassing.
2. TVOCs: A Chemical Cocktail
● Definition: TVOCs encompass hundreds of volatile organic compounds — including benzene, toluene, acetone, alcohols, esters, and aldehydes.
● Sources: Paints, varnishes, adhesives, cleaning agents, air fresheners, candles, carpets, furniture, cooking, and tobacco smoke.
● Health effects:
○ Acute: Eye/nose/throat irritation, headaches, nausea, dizziness, worsened asthma.
○ Chronic: Damage to liver, kidneys, nervous system; some compounds are confirmed or suspected carcinogens.
● Thresholds: RESET Standard recommends ≤500 µg/m³ (0.5 mg/m³).
Practical actions:
● Limit use of fragranced products, candles, and harsh cleaners.
● Ventilate after cooking, cleaning, or painting.
● Avoid indoor smoking.
● Use purifiers with activated carbon filters; replace regularly.
3. The Three-Pillar Strategy
● Source control: Choose low-emission materials at the renovation stage.
● Ventilation: Natural or mechanical ventilation, at least 2–3 times daily.
● Purification: HEPA + carbon filter purifiers, maintained properly.
Conclusion
HCHO and TVOCs are invisible but carry long-term health risks that often exceed those of outdoor pollution. By managing emissions at the source, improving ventilation, and using effective purification strategies, we can create healthier indoor environments for families, employees, and students.
For those who need clearer insight into indoor pollutant levels, multi-parameter monitors such as Temtop LKC-1000S+ 2nd — which measures AQI, PM2.5, TVOC, HCHO, temperature, humidity, and particle count — can provide a more complete picture to support informed action.
References:
1. World Health Organization (WHO). Indoor air quality guidelines: selected pollutants.
👉 WHO guidelines for indoor air quality: selected pollutants
2. International Agency for Research on Cancer (IARC). Formaldehyde classification.
👉 https://www.iarc.who.int/wp-content/uploads/2018/07/pr153_E.pdf
3. U.S. Environmental Protection Agency (EPA). Formaldehyde hazard summary.
👉 CHRONIC RESPIRATORY EFFECTS OF INDOOR FORMALDEHYDE EXPOSURE | Science Inventory | US EPA
4. U.S. Environmental Protection Agency (EPA). Volatile Organic Compounds’ Impact on Indoor Air Quality.
👉 Volatile Organic Compounds' Impact on Indoor Air Quality | US EPA
5. Minnesota Department of Health. Volatile Organic Compounds (VOCs) in Your Home.
👉 https://www.health.state.mn.us/communities/environment/air/toxins/voc.html
6. Sensirion. Information Note – VOC Index.
👉 https://sensirion.com/media/documents/02232963/6294E043/Info_Note_VOC_Index.pdf
7. RESET Standard – Air Quality for Commercial Interiors.
