What's in my air
VOCs — the pollutants HEPA does nothing about
Volatile organic compounds are carbon-based chemicals that evaporate at room temperature — a class of hundreds of substances rather than a single pollutant, ranging from harmless to genuinely hazardous.
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 |
|---|---|---|
| India | No indoor TVOC standard | India has no statutory indoor air quality standard for homes. Benzene is regulated in ambient air at 5 µg/m³ annual under NAAQS. |
| WHO indoor guidelines | Set for individual compounds, not TVOC | WHO sets indoor values for specific compounds including benzene, formaldehyde, naphthalene, trichloroethylene and tetrachloroethylene. It does not set a TVOC guideline, because the concept aggregates substances of vastly different toxicity. |
| Common indoor air practice | Below 0.3 mg/m³ TVOC often cited as 'good' | This is a rule of thumb used in building assessment, not a health-based limit. Do not treat it as one. |
Where it comes from
New furniture and engineered wood
Adhesives in plywood, MDF and particleboard off-gas for months to years. The 'new furniture smell' is exactly this.
Paints, varnishes and adhesives
Highest immediately after application, declining over weeks. Low-VOC paints materially reduce it.
Cleaning products and air fresheners
Direct and often intense sources. Air fresheners add VOCs to mask odours caused by VOCs.
Cooking
Generates VOCs alongside particulates, particularly at high temperature.
Personal care products
Aerosols, perfumes and solvents in a small bathroom produce brief high peaks.
Attached garages and generators
Petrol vapour and exhaust infiltrate readily through connecting doors.
Why it matters
- The category spans compounds of very different concern. Benzene and formaldehyde have WHO indoor guideline values and established health associations; limonene from a citrus cleaner does not belong in the same sentence.
- That is exactly why a single TVOC number is unhelpful — 500 ppb of one compound and 500 ppb of another can mean entirely different things.
- Short-term effects reported at elevated indoor VOC levels include eye and airway irritation and headache, and they are the practical reason most households notice the problem at all.
- Concentrations indoors are routinely higher than outdoors, because the sources are indoors and the ventilation rate is low.
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? | Many VOCs are smellable at low concentration — which is useful and misleading. Some of the more concerning compounds have poor odour warning, so an absence of smell means little. |
| What a consumer monitor shows | Consumer 'TVOC' sensors are metal-oxide semiconductors. They respond to a broad mix of reducing gases and are calibrated against a single reference compound, so the ppb number displayed is an indication of change, not a concentration of anything specific. They also drift, and they respond strongly to alcohol — which is why cleaning near the monitor spikes the reading. |
| Field test | Passive badge samplers analysed by a laboratory give real per-compound numbers. Worth doing once for a new build or after major renovation; not a routine household test. |
| Laboratory test | VOC speciation by GC-MS from a passive or pumped sample — US EPA TO-17 or equivalent thermal desorption GC-MS (indicative ₹6,000–₹20,000) |
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
Opening windows dilutes indoor VOCs with outdoor air that almost always contains less of them. Free, immediate, and the correct first answer for most VOC problems.
Caveat: Trades against outdoor particulates. On a high-AQI day, ventilate when outdoor levels are lowest — usually mid-morning to early afternoon.
- Activated carbon, by weightDepends
Substantial with sufficient carbon mass and contact time
Genuine adsorption of most VOCs. The effectiveness is a function of carbon mass, granule size and residence time in the bed.
Caveat: This is where air purifier specifications become evasive. Ask for carbon mass in grams or kilograms. A serious VOC filter carries hundreds of grams to several kilograms; a carbon-impregnated mesh weighs tens of grams and is essentially an odour pad.
- Impregnated / chemisorbent mediaPartial
Potassium permanganate and similar media chemically convert specific compounds including formaldehyde, which plain carbon adsorbs poorly.
Caveat: Compound-specific. Media that handles formaldehyde well may do little for solvents.
- Photocatalytic oxidation (PCO)Depends
Uses UV and a catalyst to break VOCs down. Laboratory performance varies widely.
Caveat: Incomplete oxidation can produce formaldehyde and other by-products from the compounds being destroyed, and some units generate ozone. Treat claims sceptically and look for independent by-product testing.
- Source substitutionEffective
Low-VOC paints, solid wood or low-emission board, unscented cleaning products. Prevents the problem rather than chasing it.
What does not work
Each of these is commonly assumed — or actively marketed — to help with volatile organic compounds (vocs). None of them do.
HEPA filtration
HEPA is a mechanical particle filter. VOC molecules are thousands of times smaller than the particles it captures and pass through completely unaffected.
Ionisers
No meaningful VOC removal, and the reactive chemistry involved can generate formaldehyde and ozone as by-products.
Ozone generators
Ozone reacts with some VOCs, but the reaction products include formaldehyde and ultrafine particles. You are trading a problem for a worse one, in a room you are breathing in.
Air fresheners
They add VOCs and mask odour. This is the opposite of remediation, and it is worth stating plainly because it is the most common household response.
Houseplants
Chamber studies showed VOC uptake at rates that, scaled to a real room's air exchange, would require an implausible number of plants. Keep them because you like them.
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.
- Air out new furniture, mattresses and rugs in a ventilated space — a balcony or spare room with the window open — for as long as you can before bringing them into a bedroom.
- Specify low-VOC paint and give a freshly painted room a week of ventilation before sleeping in it.
- Store solvents, paints and adhesives outside the living envelope. A sealed tin still emits.
- Never use an air freshener to deal with a smell you have not identified. Find the source instead.
- Ventilate during and after cleaning — most spike events in monitored homes are cleaning products, not outdoor air.
How to read an air purifier's carbon claim
Almost every air purifier sold in India claims activated carbon. The claims are not comparable, and the specification that distinguishes them is almost never printed.
What matters is carbon mass and contact time. A gas passing through a thin carbon-coated mesh spends milliseconds in contact with it and little is adsorbed. A gas passing through a deep bed of granular carbon spends far longer and much more is adsorbed.
So the question to ask a manufacturer is: how many grams of activated carbon does this filter contain? A unit designed for VOC removal will answer with a number in the hundreds of grams or in kilograms. A unit whose carbon is a deodorising layer will not answer at all.
Important
Frequently asked questions
Does a HEPA filter remove VOCs?
How much activated carbon does an air purifier need for VOCs?
Is a TVOC reading on my monitor accurate?
How long does new furniture off-gas?
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.
National Ambient Air Quality Standards (NAAQS), notification dated 18 November 2009
Central Pollution Control Board, Ministry of Environment, Forest and Climate Change · published 2009-11-18 · checked 2026-08-01
India's legally applicable ambient air standards. They are ambient (outdoor) standards — India has no equivalent statutory indoor air quality standard for homes.
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.