We need to stop calling recirculating fans “vents.” A fan above your stove that moves smoke from under your microwave to above your microwave is just a noisy “forehead greaser.” If you aren’t venting the heat, humidity, smoke, grease, and odor outside, you’re just moving the problem around!
A lot of houses, especially newer builds and condos, come with an over-the-range microwave that has a fan built into the bottom. It sucks air up from the stovetop, pushes it through a thin mesh filter, and blows it right back into the kitchen, usually at the height of your face. The grease filter catches some of the big droplets. A charcoal filter, if there is one and if anyone has ever replaced it, might catch some odor. Everything else, including the heat, steam, and smoke, stays in the house.
Why It Matters#
Cooking puts a lot into the air. Searing a steak or frying anything sends grease and fine particles into the room. Boiling water adds humidity. And if you cook on a gas stove, you’re also burning fuel indoors. Researchers have found that gas stoves release nitrogen dioxide and other pollutants that can build up in a kitchen to levels you wouldn’t accept outside, especially in smaller homes with poor ventilation.
If you don’t vent it, it goes somewhere. The grease settles on your cabinets, ceiling, and walls as that sticky film that’s impossible to clean. The humidity can lead to condensation and mold. And the smell of last night’s fish hangs around the living room until Thursday.
What Actually Works#
A ducted range hood that exhausts to the outside is the real solution. A few things make a big difference:
- Size and capture. A hood that’s at least as wide as your cooktop, and ideally a little wider, catches more of the rising plume. Deeper hoods capture better than shallow ones.
- Use the back burners. The rear burners sit more directly under most hoods, so they capture much better than the front ones.
- Turn it on before you start cooking, and leave it running for 10 to 15 minutes after you’re done.
- Keep the filters clean. Most metal grease filters can go right in the dishwasher.
- Mind the makeup air. Very powerful hoods pull a lot of air out of the house, and that air has to come back in from somewhere. Building codes in many areas require a makeup air system for hoods over 400 CFM, so talk to a pro before installing a huge one.
If You’re Stuck With a Recirculating Fan#
Not everyone can cut a hole in the wall, especially renters. If that’s you, there are still ways to help:
- Replace the charcoal filter regularly. Most people never have.
- Open a window and run a fan blowing out of it while you cook.
- Use lids on pots and pans to cut down on steam and splatter.
- Consider an induction cooktop or a plug-in induction burner. With no flame, there’s no combustion pollution, and they heat fast.
When you replace that microwave someday, think about whether you can swap it for a real hood. Your cabinets, your lungs, and your forehead will thank you.
