Everyone always says eat your green beans. But they may never have said to avoid inhaling them.
"Food generates a lot of small particles. As well as volatile organic compounds, that oftentimes we would like to minimize our exposure to, while we're cooking," said mechanical engineer Woody Delp.
And that's why your kitchen stove might have a hood over it. But how much good is it actually doing?
"You can probably get the aroma of peanut oil and beans throughout the room, which is an indication that this is not removing everything as we're cooking," said Delp.
There is a carefully controlled room at the Lawrence Berkeley National Laboratory where scientists can measure all sorts of things you can't see.
"We should see a number start to come up - and there it is. It's representing the CO2 that is being captured by our hood," said Delp.
The scientists aren't doing this because they don't want people to cook; they are doing it because they want to create a rating system. So when you go out to buy a hood for your stove, you know how well it actually does its job.
"Right now, if you go to buy a range hood, you have no idea how effective it is. You can see how much air it moves but that doesn't necessarily mean it removes the pollutants and the moisture from your home," said Berkeley Lab Staff Scientist Brett Singer.
Scientists say it's especially important for new, energy-efficient homes that are completely sealed off.
"The more you make that home tight, the more you need to pay attention to the chemicals and other pollutants you release into the home. So that's where the extra ventilation comes in," said Singer.
The lab found it's not just the fan that matters; though that's part of it. Hoods that are bigger, work better.
"The plume flows up along the sides of the wok and that puts it even further from the front of the range hood," said Delp.
And if an oven hood doesn't stick out, people should put their food on the back burner. But most important, use the hood on its highest setting. If there is no hood in your kitchen, just open a window.