When the kitchen smells even with extraction on

Usually because the extraction is grease-laden - either pulling too little air to clear the cooking smells, or the built-up stale grease itself is the smell (often both). A running extraction should clear the cooking smells, so if the kitchen smells anyway, the extraction itself is often the problem. Two grease-related causes: it's grease-choked (clogged filters, grease-laden ductwork, a strained fan), so it pulls too little air to clear the smells, which linger despite the fan running; or the built-up old grease in the system is itself the source of a stale, rancid smell that pervades the kitchen regardless of the extraction (and the running fan can spread it). Often both together - a grease-laden system under-performs and smells. So a smell despite the extraction usually means a grease-laden system needing cleaning. (Other causes - drainage, a ductwork fault, make-up air - are possible if cleaning doesn't resolve it.) So it smells because the extraction is grease-laden. So because the extraction is grease-laden. This is general commentary.

Yes - old, stale grease built up in the canopy, ductwork and fan develops a rancid smell that pervades the kitchen regardless of the extraction, and the running fan can spread it. Beyond under-performing, a heavily grease-laden extraction can be the source of the smell itself. Old grease accumulated in the system (canopy, ductwork, fan) develops a distinctive rancid, stale-grease odour - the smell of the aging grease, not of current cooking. This smell pervades the kitchen regardless of whether the extraction is on, because it's coming from the grease in the system. And the running extraction can make it worse - drawing air over the greasy surfaces and wafting the smell around (and out to the neighbours). So yes - a grease-laden system is a genuine source of odour, and one that running the extraction doesn't fix (and may spread). Cleaning removes the grease and the smell. So yes - stale grease in the system smells. So yes - the built-up grease can smell. This is general commentary.

Usually yes, where a grease-laden system is the cause - cleaning restores the airflow (so it clears the cooking smells) and removes the stale grease (the smell source), resolving both; other causes can be checked if it persists. When the smell is caused by a grease-laden extraction (the common case), cleaning addresses it directly: removing the grease restores the airflow, so the system clears the cooking smells effectively again; and it eliminates the built-up stale grease that was the odour source. So cleaning usually clears the smell - resolving both the under-performance and the stale-grease smell. It also controls the fire risk (a bonus). If the smell persists after a proper clean, other sources may be involved (a drainage or grease-trap smell, a ductwork fault, a make-up-air problem), which can then be investigated. But cleaning is the first and usually effective step for a kitchen that smells despite the extraction. So usually yes - cleaning clears a grease-caused smell. So yes, usually, when grease is the cause. This is general commentary.

No - masking doesn't fix the cause (a grease-laden extraction) and leaves the fire risk; the smell will persist and the grease keeps building, so cleaning the system is the real answer. Air fresheners or masking agents cover the smell temporarily but do nothing about its cause. If the smell is from a grease-laden extraction (under-performing and/or the grease smelling), masking leaves the underlying problem: the extraction still isn't clearing the smells (so they keep returning), the stale grease is still there (still smelling), and - importantly - the grease build-up remains a fire risk. So masking is a poor response: it hides a symptom of a real problem (a neglected, grease-laden, fire-risk extraction) rather than fixing it. The real answer is to have the extraction cleaned - which removes the grease, clearing the smell at its source, restoring the airflow, and controlling the fire risk. So no - don't mask it; clean the system. So no - masking leaves the cause and the fire risk. This is general commentary.

Then other sources may be involved - a drainage or grease-trap smell, a ductwork fault (a leak), or a make-up-air problem - which can be investigated; but a grease-laden extraction is the common cause, so cleaning is the right first step. A grease-laden extraction is a common cause of a kitchen that smells despite the extraction, so cleaning it usually resolves the smell. But if a proper clean doesn't fully clear it, other sources should be considered: a drainage or grease-trap smell (a different origin - drains, traps, waste); a ductwork fault (a leak letting smells escape or drawing them in); a make-up-air or ventilation imbalance (poor air movement letting smells linger); or another source in the kitchen. So if cleaning doesn't fully resolve the smell, investigate these other possibilities. But cleaning the extraction is the right first step (addressing the common cause, and the fire risk), before looking further. So other sources can be checked if cleaning doesn't fully resolve it. So investigate other sources if it persists. This is general commentary.

Often yes - if the smell is from a grease-laden extraction, that same grease is a fire risk, so the smell can be a useful warning that the system needs cleaning for safety as well as odour. When a kitchen smells because the extraction is grease-laden (under-performing and/or the grease smelling), the smell and the fire risk share a cause: the built-up grease. So a persistent stale-grease or cooking smell despite the extraction running can be a useful warning sign that the system is grease-laden - which means it's a fire risk (the grease is fuel) as well as an odour problem. In that sense, the smell is doing you a favour by flagging a system overdue for cleaning. Cleaning it addresses both at once: clearing the smell and removing the fire fuel. So a grease-caused smell often does signal a fire risk - another reason to have the system cleaned promptly, not just to fix the smell. So yes - the smell can flag a fire-risk grease build-up. So often yes - the grease is a fire risk too. This is general commentary.