A range hood's job goes beyond clearing smoke and cooking odors — for a gas or propane stove specifically, it's addressing measurable indoor air pollution, and how well it does that job varies a lot between models.
What a range hood is actually removing
Gas and propane stoves release combustion byproducts into the air as they burn, including nitrogen dioxide (NO2), a pollutant the EPA has identified as causing respiratory symptoms, particularly in people with asthma. Recent research modeling actual US homes found that typical gas stove use raises long-term indoor NO2 exposure meaningfully — and that ventilation is one of the biggest factors determining how much of that exposure actually reaches the people in the kitchen. Electric and induction cooktops don't produce this NO2 byproduct at all, since there's no combustion involved, which is a genuine advantage of those cooking technologies if avoiding this exposure is a priority — but for a household keeping a gas stove, hood quality and consistent use are the practical levers that matter.
Capture efficiency, and consistent use, both matter — a lot
The same research found that people without an outside-venting hood, or who have one but don't use it, are exposed to roughly 25% more long-term stove-attributable NO2 than average. People with a well-performing, outside-venting hood (measured in that research at 75% capture efficiency) who use it every time they cook were exposed to roughly 70% less long-term NO2 than average — a genuinely large difference, not a marginal one. This means two things matter almost equally: buying a hood that actually vents outside (not simply recirculating filtered air back into the room) and rated for reasonably high capture efficiency, and actually turning it on every time the stove is used, not just for particularly smoky or smelly cooking.
Recirculating vs. vented-outside hoods are not equivalent
A vented hood pulls air through ductwork to the outside, physically removing pollutants and moisture from the home entirely. A recirculating (ductless) hood filters air through a charcoal or grease filter and releases it back into the kitchen — it can reduce smoke and odor to some degree, but does not remove gaseous pollutants like NO2 from the home the way true outside venting does. If installation allows for it, a properly vented hood is a meaningfully better choice for actual air quality, not just a marginal upgrade over a recirculating model.
CFM sizing should match stove output, not just kitchen size
Range hood airflow capacity, in CFM (cubic feet per minute), should be matched to the stove's total BTU output — a general guideline used by some manufacturers suggests roughly 1 CFM per 100 BTUs of cooktop output, though specific manufacturer guidance for a given range is worth checking directly. An undersized hood, even a "vented" one, won't effectively capture and remove what a powerful cooktop actually produces, regardless of its recirculating-vs-vented design.
The one thing people forget
Turn the range hood on before starting to cook, not partway through or only when something starts smoking — capture efficiency depends on the hood already having established airflow before pollutants are released, and switching it on reactively after cooking has already started misses some of the exposure the hood could have prevented from the very first moment of cooking.