Most Indian kitchens today have some form of mechanical ventilation already, a wall-mounted exhaust fan, a chimney hood, or both. Most also run on LPG or PNG. Having the equipment is not the same as it working. A chimney that is undersized, mounted too high, set to recirculate instead of duct outside, or simply switched on too late does very little for the pollutants that matter most.
This guide is not about buying ventilation. It is about why cooking pollution still builds up in kitchens that already have a hood or fan, and what changes that.
What you're actually trying to remove
Two pollutants matter most: nitrogen dioxide (NO₂) from gas combustion, and fine particulate matter (PM2.5) from oil, spices, and browning food.
Field studies on gas stove cooking have measured NO₂ peaks reaching into the hundreds of parts per billion during active cooking, often exceeding the US EPA's 1-hour outdoor NO₂ standard (100 ppb, the level set by the National Ambient Air Quality Standards) within a few minutes of lighting a burner. Homes without an exhaust hood in place have been observed to exceed that outdoor standard. PM2.5 comes mainly from the cooking process itself, frying and high-heat cooking generate far more than boiling or steaming, and a US simulation study across 1,000 homes identified cooking as the largest indoor source of PM2.5 in the homes modelled.
Neither pollutant requires visible smoke to reach potentially harmful indoor concentrations, and neither is something you'd necessarily notice in the moment. NO₂ in particular is colourless and odourless on its own. NO₂ exposure at these levels is linked to worse asthma symptoms and higher asthma risk in children, and to increased risk of chronic lung and cardiovascular disease in adults with repeated exposure over time. PM2.5 penetrates deep into the lungs and bloodstream; long-term exposure is linked to heart disease, stroke, and reduced lung function, and short-term spikes, like a cooking session, can worsen existing respiratory or cardiac conditions. For a wider look at what's typically in indoor air and where it comes from, see our overview of indoor air pollutants and how indoor concentrations compare with outdoor air.
For context: cooking-level NO₂ and PM2.5 concentrations fall in the same range CPCB classifies as Poor to Severe on India's own AQI scale. AQI itself is calculated from a full day's average rather than a short cooking-time spike, so this isn't a literal AQI reading, but it puts the scale in perspective: a closed kitchen with the stove on can briefly reach concentrations most people would go out of their way to avoid if reported as the day's outdoor air quality. If you want to see how CPCB's scale is built and how it differs from other systems, we cover it in India AQI vs US AQI, and you can check your local reading via the AQI checker.
One question worth answering directly: does it matter if you cook on LPG or PNG? Both burn gas at the cooktop and produce NO₂ and CO. PNG is sometimes marketed as "cleaner-burning," but that claim is usually about broader environmental factors, not measured indoor NO₂ or CO from home cooking, and we couldn't find solid data showing a real difference between the two for kitchen air. Ventilation matters the same amount either way; switching fuels isn't a shortcut around it.
Why an installed hood or fan often underperforms
Capture efficiency, not CFM, decides what actually gets removed. Capture efficiency is the percentage of pollutants generated at the cooktop that are pulled directly into the hood and exhausted, rather than escaping into the room. Laboratory testing on residential hoods has found capture efficiency ranging from over 90 percent down to around 30 percent, on hoods with similar airflow ratings. What changes it: mounting height above the burner, how far the hood overhangs the front burners, and which burner is in use. Front burners, closer to the cook and further from the hood, are consistently captured worse than back burners on the same hood. A CFM number on the box tells you almost nothing about this, and capture efficiency is rarely disclosed by chimney manufacturers selling in India, who tend to advertise suction (m³/hr) alone.
Recirculating hoods are not a meaningful control for combustion gas. A recirculating (ductless) hood passes air through a grease and carbon filter and releases it straight back into the kitchen. It reduces odour and traps some grease, but it does nothing for CO or heat, both of which pass straight through. These carbon filters are built and marketed for odour and VOC removal, not NO₂ (our filter explorer covers what different filter media are actually tested for). We found no evidence that they're tested or rated for NO₂ removal, and any effect would likely be small and quickly used up. If your hood is not connected to ducting that exits the building, treat it as a partial solution for grease and smell, not for combustion gas. Check this once: if there is no visible duct running from the hood to an external wall or shaft, it is almost certainly recirculating.
Mounting height matters more than most installers treat it. A hood mounted higher than the manufacturer's recommended range, often done for headroom or aesthetics, loses capture efficiency sharply, because the plume has more distance and more air currents to disperse into before reaching the filter.
Clogged filters quietly cut airflow. A grease filter loaded with months of residue can reduce a hood's real-world airflow well below its rated CFM, even though the motor itself is unchanged. This is one of the most common gaps between a hood's spec sheet and how it actually performs in daily use.
What "suitable for Indian cooking" actually means
Most of the engineering research behind hood design and capture efficiency testing was done in North America and Europe, on cooking patterns generally lighter than a typical Indian kitchen: shorter sessions, less oil, less continuous high heat. There isn't much research comparing capture efficiency directly across cooking styles, so what follows is engineering reasoning applied to Indian cooking, not a finding from Indian-specific studies.
Indian cooking often involves deep frying, tempering (tadka), and spice roasting, which can generate substantially more oil aerosol and particulate per session than boiling or light sautéing. Meals are often cooked back-to-back rather than as one short session, so the exhaust runs longer and under heavier load than the intermittent use most hoods are tested around. Tempering in particular is one of the heaviest short bursts of oil and heat in the whole cooking process, and it often happens right at the front of the hob.
Ducted matters more here, not less. The case for ducted over recirculating was covered above; the reason it matters even more in an Indian kitchen is simple. Combustion gas exposure scales with how long and how often the stove runs, and longer, more frequent sessions mean more cumulative NO₂ and CO if that gas has nowhere to actually leave the building.
Size with margin above the bare minimum. A hood sized for light, occasional cooking will be working at its ceiling constantly in a kitchen that fries or tempers daily. Where budget allows, more headroom on suction capacity matters more here than in a kitchen that mostly boils and steams.
Baffle filters tend to hold up better under continuous heavy oil load. This is a mechanical trade-off, not a brand preference. A baffle filter is a durable metal design that tolerates grease well and mainly requires periodic cleaning, though coatings and welds can still wear over many years. A filterless system routes oil past a sealed motor, and how well that holds up under heavy, frequent frying depends on whether the auto-clean mechanism genuinely uses heat to liquefy grease, or simply collects it in a cup with a fan, which leaves the motor more exposed to grease over time. Under daily frying and tempering, baffle is the more forgiving mechanical choice; filterless leans harder on that auto-clean mechanism working as intended.
If you temper on the front burner, front overhang matters more than the suction rating on the box. Tempering is one of the oiliest, highest-heat steps in Indian cooking, and the front burner is where capture efficiency is weakest on most hoods (covered above). If that's your habit, check the hood's front overhang and mounting height before you check its m³/hr figure.
Motor design and build quality matter more the longer and more often you cook, but you can't check this before buying. Manufacturers rarely publish anything that lets you compare it directly. It's one reason two hoods with similar suction ratings may not perform equally well over years of regular use, alongside things like duct installation and maintenance.
Noise matters because a noisy exhaust gets switched off. In an open-plan or kitchen-dining layout, a hood that's unpleasant to run for the length of a full Indian cooking session will get turned off early, especially once the visible smoke has cleared. Ventilation that isn't running doesn't help, however good its rated capture efficiency is.
In short: a ducted hood, sized with margin, positioned to actually cover the front burner if that's where you temper, with a filter type matched to how much you fry rather than how little maintenance you want.
The role of windows and other kitchen features
A few features of the kitchen's layout and how it's used during cooking either support the exhaust system or work against it.
A window right behind or beside the hood can reduce capture efficiency if it creates a cross-draft across the cooktop. Not every open window nearby is a problem; it depends on wind, window size, and whether the resulting airflow cuts directly across the burners. When it does, the draft shears the rising plume sideways before the hood has a chance to capture it, pushing smoke and oil aerosol into the room instead of up into the filter. This is why several chimney manufacturers' own installation guidance advises against a window directly behind or adjacent to the hood, or recommends keeping it closed while the hood is running.
Cross-ventilation should flow past the stove, not through it. The useful version of "open a window" is air entering from one side of the kitchen, away from the hob, and exiting through the hood on the other. That supplies the makeup air the exhaust needs without disturbing the plume directly above the burner. When to open windows in the rest of the home depends on outdoor AQI and indoor build-up, which we walk through in should I open my windows? and the ventilation guide tool.
Crack a window or door on the opposite side of the kitchen while the exhaust runs, not just for comfort. A strong exhaust running without enough incoming air depressurises the kitchen. If there's another gas appliance nearby, like a gas geyser, that negative pressure can pull its combustion products back indoors instead of out through its own vent. This is one of the mechanisms behind stale indoor air that isn't obvious from smell alone.
Closing the kitchen door has trade-offs. It contains pollutants to a smaller volume so the exhaust clears them faster, but a fully sealed kitchen also starves the exhaust of makeup air; a door left slightly ajar, combined with a window on the opposite wall, tends to work better than either extreme.
Duct length and bends quietly cut into a hood's real-world airflow. A hood's rated CFM or m³/hr figure is measured with no ductwork resistance at all. Every extra metre of duct, and especially every 90-degree bend, adds resistance that reduces the airflow actually reaching the kitchen. A kitchen positioned near an exterior wall, with a short, straight duct run, will get meaningfully closer to a hood's rated performance than one at the far end of a flat with a long or bent duct path to the outside. This is worth weighing during a kitchen layout or renovation, not only when picking a hood.
If ducting outside isn't possible at all (compact or fully enclosed kitchens with no external wall or shaft), place a HEPA air purifier in an adjoining living space, not beside the cooktop (our guide on air purifier placement covers why proximity and room geometry matter). It can help reduce PM2.5 that escapes into the rest of the home, but does little for exposure at the stove itself, where levels are highest, and nothing for NO₂ or CO. Keep it away from heavy frying directly, since grease clogs filters faster than ordinary dust, and clean intake sensors on a schedule (see sensor cleaning). Ducted exhaust remains the primary fix; this is a backup for the rest of the house, not a replacement for it. If you're choosing a unit for that adjoining space, the air purifier finder and buying checklist help narrow it down.
Habits that matter as much as the equipment
- Switch on the exhaust before you start cooking, not after you notice smoke or smell. NO₂ builds within the first few minutes of the burner lighting, well before anything is visible.
- Use the back burners for anything producing a strong plume (frying, tempering, roasting spices) if your hood design and burner layout allow it, for the capture-efficiency reasons covered above.
- Leave the exhaust running for several minutes after cooking ends, to clear NO₂ and fine particulate that linger after visible smoke has settled.
- Clean or replace grease filters on a regular schedule. A visibly clean filter can still be significantly loaded on the inside; go by time or usage, not appearance alone.
- If you have an exhaust fan without a hood, or in addition to one, make sure it has somewhere to draw makeup air from. Covered in more detail above, alongside other window and layout factors.
This article is general guidance, not medical advice. If you have asthma, severe allergies or persistent respiratory symptoms, consult a qualified doctor.
Sources
- Institute for Policy Integrity, NYU School of Law, The Emissions in the Kitchen (gas stove NO₂ and PM2.5 emissions).
- Kadiri et al., Determinants of Indoor NO₂ and PM2.5 Concentration in Senior Housing with Gas Stoves, Toxics (2024), via PMC.
- Kadiri et al., Effectiveness of HEPA/Carbon Filter Air Purifier in Reducing Indoor NO₂ and PM2.5 in Homes with Gas Stove Use in Lowell, Massachusetts, Toxics (2025), via PMC/PubMed.
- World Health Organization, WHO Guidelines for Indoor Air Quality: Selected Pollutants (2010), nitrogen dioxide chapter.
- US EPA, Health and Environmental Effects of Particulate Matter (PM).
- CPCB, National Air Quality Index (breakpoints and categories).
- Lawrence Berkeley National Laboratory, Performance Assessment of U.S. Residential Cooking Exhaust Hoods.
- California Energy Commission, Effective Kitchen Ventilation for Healthy Zero Net Energy Homes.
- Lawrence Berkeley National Laboratory, Development of a Standard Capture Efficiency Test Method for Residential Kitchen Ventilation.
- ASHRAE Standard 62.2, Ventilation and Acceptable Indoor Air Quality in Residential Buildings.
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