What's in my air
Formaldehyde — the one VOC with a specific indoor guideline
Formaldehyde is a colourless gas with a sharp odour, released principally by the urea-formaldehyde adhesives in plywood, MDF and particleboard, and one of the few indoor pollutants with a specific WHO guideline value.
Limits and standards
India's NAAQS are ambient (outdoor) standards, and there is no statutory Indian indoor air quality standard for homes. WHO's guideline values are health-based targets rather than regulatory limits, and are consistently stricter.
| Standard | Limit | What it means |
|---|---|---|
| WHO indoor air quality guideline | 0.1 mg/m³ (30-minute average) | WHO states that this value prevents sensory irritation in the general population and is also protective against longer-term effects. |
| India | No statutory indoor limit | India has no indoor air quality standard for homes. Emission-class labelling of boards (E0, E1, E2) is voluntary in practice. |
Where it comes from
Urea-formaldehyde bonded boards
Plywood, MDF, particleboard and HDF. The dominant residential source, and the reason a newly fitted modular kitchen smells the way it does.
Laminates and adhesives
Contact adhesives and edge banding contribute alongside the board itself.
Textiles and upholstery finishes
Wrinkle-resistant finishes on curtains and bedding release small amounts.
Combustion
Cooking, smoking and incense produce formaldehyde as a combustion product.
Secondary formation
Ozone reacting with terpenes from citrus cleaners and air fresheners forms formaldehyde in the room. This is a specific and well-documented reason not to run an ozone-generating device.
Why it matters
- WHO classifies formaldehyde as a human carcinogen, and its indoor guideline is set at a level intended to prevent sensory irritation as well as longer-term effects.
- Sensory irritation — burning eyes, sore throat, nasal irritation — occurs at concentrations people can notice, and is the usual reason a household investigates.
- The Indian relevance is specific: modular furniture in engineered wood has become standard in new flats, and the emission rate rises with the temperature and humidity that Indian homes experience for much of the year.
Note
Can you detect it yourself?
Consumer air quality monitors are genuinely useful for tracking change and poor at absolute measurement. Knowing which of the two you are looking at prevents most of the disappointment in this category.
| Question | Answer |
|---|---|
| Can you sense it? | A sharp, pungent smell often noticed on first entering a newly furnished room. The odour threshold varies considerably between people, so absence of smell is not evidence of absence. |
| What a consumer monitor shows | Some consumer monitors display an 'HCHO' figure. Inexpensive electrochemical formaldehyde sensors cross-respond to alcohols and other VOCs and drift over time, so treat the number as indicative. A reading that falls sharply when you open a window is telling you something real; the absolute value is not reliable. |
| Field test | Passive DNPH badge samplers analysed by a laboratory give a genuine 24-hour or 7-day average. Worth doing once after a major fit-out. |
| Laboratory test | Formaldehyde by DNPH cartridge and HPLC — US EPA TO-11A or equivalent (indicative ₹4,000–₹12,000) |
What removes it
Effectiveness ratings below describe the technology working correctly, within its service life, on water or air that suits it. “Depends” means there is a condition in the caveat that decides the outcome — read it before buying.
- VentilationEffective
The most effective and cheapest intervention. Emission continues regardless, but concentration is a balance between emission rate and air exchange, and ventilation moves that balance directly.
- Chemisorbent media (potassium permanganate, amine-treated carbon)Effective
Chemically converts formaldehyde rather than merely adsorbing it. This is what a genuine formaldehyde filter uses.
Caveat: Consumable with a finite capacity, and it is not what most 'activated carbon' filters contain.
- Bake-out / airing before installationPartial
Emission falls with time and accelerates at higher temperature. Letting new furniture stand in a hot, well-ventilated space before installing it removes a share of the total emission before it reaches your bedroom.
- Sealing exposed board edgesPartial
Cut edges of MDF and particleboard emit far more than laminated faces. Sealing them with a low-VOC lacquer or edge banding measurably reduces emission.
- Low-emission board specification (E0 / E1)Effective
The intervention that works best is choosing the material. Ask for the emission class in writing at the quotation stage — after installation it is an expensive thing to fix.
What does not work
Each of these is commonly assumed — or actively marketed — to help with formaldehyde. None of them do.
HEPA filtration
A gas. HEPA removes none of it.
Plain activated carbon
Formaldehyde is a small, poorly-adsorbing molecule. Standard carbon has low capacity for it and releases it readily as conditions change — which is why formaldehyde-specific filters use treated media instead.
Ozone generators and ionisers
Actively counterproductive. Ozone reacting with terpenes in the room generates formaldehyde, and photocatalytic and ionising devices can produce it as a partial-oxidation by-product.
Houseplants
The classic chamber study on formaldehyde uptake by plants does not scale to a real room's air exchange rate.
Source control that beats filtration
For most indoor pollutants the highest-leverage intervention is not a device. These are the changes worth making before, or instead of, buying anything.
- Specify E0 or E1 emission-class board for modular furniture, and get the class written into the quotation.
- Air new furniture out before it goes into a bedroom. Bedrooms are where exposure duration is longest.
- Ventilate a newly fitted kitchen or wardrobe aggressively for the first several weeks — this is the period of highest emission.
- Do not use ozone-generating devices, and be cautious with citrus-scented cleaners in rooms with new engineered wood.
- Run air conditioning at a lower setpoint where practical during the first months; emission rate is strongly temperature-dependent.
Frequently asked questions
What is a safe formaldehyde level indoors?
Does plywood release formaldehyde?
Does an air purifier remove formaldehyde?
How long does formaldehyde off-gassing last?
Sources
Every limit and standard quoted on this page comes from one of the documents below. Where a figure is not in one of these, we have not published it.
WHO Guidelines for Indoor Air Quality: Selected Pollutants
World Health Organization · published 2010-01-01 · checked 2026-08-01
Covers formaldehyde, benzene, carbon monoxide, naphthalene, nitrogen dioxide, PAHs, radon, trichloroethylene and tetrachloroethylene specifically as indoor pollutants.
California Air Resources Board · checked 2026-08-01
CARB certification requires air cleaners sold in California to emit under 0.050 ppm ozone. It is the most widely referenced independent check on whether a device adds ozone to indoor air.
This page states what published standards say and what the physics of each technology allows. It does not state what is in your supply — no page can. Where the two questions meet is a test result, and every entry in this library says which test to ask for.