Posted tagged ‘air pollution’

Use your range hood for a healthier home, advises indoor air quality expert Brett Singer

March 9, 2018

Photo courtesy of Brett Singer.

Most Americans don’t realize cooking can be a major source of indoor air pollutants, unless they’ve recently burned something on the stove. But studies have shown that cooking-related contaminants can cause health problems such as respiratory illness and asthma attacks.

To learn more, I spoke with Brett Singer, PhD, a scientist at Berkeley Lab who investigates indoor air quality. Recently, he measured the levels of pollutants emitted from gas cooking burners and ovens in several Bay Area homes. I asked him about this study and for advice on how to reduce cooking pollutants.

Are harmful pollutants emitted when cooking?

“A gas burner almost always produces significant quantities of nitrogen dioxide, which is a respiratory irritant. Depending on the burner configuration, it can also produce carbon monoxide, which is regulated by the Environmental Protection Agency. In general, newer cooktop burners don’t produce much carbon monoxide because of design improvements. Finally, the gas produces ultrafine particles, smaller than 100 nanometers, which are dangerous because they can move around your body in ways that larger particles can’t.

Electric burners don’t produce carbon monoxide and produce only small amounts of nitrogen dioxide. But an electrical coil burner can produce ultrafine particles, particularly when you first turn it on.

Cooking food on either type of burner also produces fine particles and some organic chemicals, including acrolein and polynuclear aromatic hydrocarbons that are known to be hazardous. Frying, broiling and other cooking at high temperatures generally produces more pollutants.

However, these pollutants can be easily addressed with good kitchen ventilation, which is especially important if you live in a small home.”

What did your in-home study find?

“We went into moderately sized homes — eight 1,400 to 2,500-square-foot homes and one small apartment — with common, well-functioning equipment that had been in use for a few years. We measured the concentrations of pollutants in the kitchen and elsewhere as we boiled and steamed water on the cooktop and/or oven, with and without ventilation. We found issues in half of these homes and that’s not good. In four of the homes, we showed that the gas-cooking burners emitted enough nitrogen dioxide to exceed the health standards for outdoor air.”

What are your tips to minimize these cooking pollutants?

“The first tip is to ventilate when you cook, and to ventilate more the more you cook. Range hoods are the most effective way to do this, if your range hood actually moves air out of the kitchen. If you have a range hood that just recirculates air back into the kitchen, you need to use another exhaust fan — for example, from a nearby bathroom — or open windows.

You also need to use your hood or exhaust fan regularly. Based on several surveys, many people only occasionally use them. People report not using them because they’re noisy, because people forget to turn them on or because they aren’t needed unless removing smoke, odors and moisture — like when frying something stinky. Those are good reasons to use ventilation, but people can’t sense pollutants, so they may not be ventilating sometimes when it’s really needed.

If you’re buying a new range hood, buy a quiet one that you like. If it isn’t quite as efficient but you’re happy with it and you’ll use it, then great. To improve on that, a range hood needs to have higher flow rates and cover the front burners.

Beyond that, almost any range hood works better if you cook on the back burners. If you put it on a low speed and cook on a single back burner, then you’ll typically capture 50 to 70 percent of the pollutants.”

What is the ultimate goal of your research?

“The goal of our work on kitchen ventilation is to help people cook all they want  — with gas or electric — without exposing themselves to harmful air pollutants. This is an important part of our broader work on high performance homes that use very little energy and provide a healthier environment for their occupants. We try to provide the science to inform builders, retrofit contractors and the general public.”

This is a reposting of my Scope blog story, courtesy of Stanford School of Medicine.

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Air Pollution Lurks Inside Your Home

April 29, 2013
photo of stir-frying

Photograph by kfisto via Creative Commons licensing.

How would you like a job that involves grocery shopping at Trader Joes with the company credit card and cooking dishes like stir-fry? This describes Tosh Hotchi’s job, but he isn’t a chef. He is part of a research team that studies how to build healthy efficient homes, including how to improve the quality of air inside a home through better ventilation. Hotchi is helping to study a major source of indoor pollutants – cooking.

When people think of air pollution, they usually picture a factory spewing a plume of toxic chemicals. But indoor air pollution causes significant health effects such as respiratory illness, asthma attacks, cancer and premature death. Californians spend over 45 billion dollars each year on these health impacts, according to a study by the California Air Resources Board.

Scientists at the Lawrence Berkeley National Laboratory (Berkeley Lab) have investigated which indoor air pollutants cause the greatest health consequences. In a paper published in Environmental Health Perspectives, they reported that fine particles with a diameter of 2.5 mm or less, formaldehyde and acrolein are the worst indoor contaminants for nonsmoking households.

Fine particulates are found indoors mainly due to cooking, burning candles or incense, and outdoor sources that leak inside. Formaldehyde is mainly emitted by materials used in home construction and furniture, such as particle board, paneling and foam insulation. Acrolein in the home is primarily from cooking, especially oils. All three of these contaminates also come from tobacco smoke.

“Think about what your putting in your home,” says Melissa Lunden, a Berkeley Lab staff engineer. “Most of us have to cook, but do you need the candles, incense and air fresheners? Freshening your air requires taking stuff out, not putting more stuff in.”

Berkeley Lab scientists are now looking for ways to improve indoor air quality, by developing better standards for residential buildings and new tests to measure these hazardous pollutants. Since cooking is a major source of indoor air pollutants, they have also evaluated the effectiveness of cooking exhaust hoods. Their study results showed that indoor air quality can be significantly improved by simply cooking on the back burners of your stove, using higher fan settings, and turning the fan on before you start cooking. Further research on cooking-induced pollutants is underway using a new demonstration kitchen to study real-life cooking conditions. During these studies, Tosh Hotchi’s stir-fry and cookies are just a happy bonus for his coworkers like Melissa Lunden.

For more information about indoor air pollution, check out my KQED Quest blog.


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