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Green Building News

The Hazards of Cooking With Gas

Researchers in California report that indoor pollution levels exceed legal outdoor limits in many homes with gas stoves

Cooking with gas contributes to poor indoor air quality, researchers have found. Pollutant levels inside can exceed legal outdoor limits, raising health concerns.

Cooking with gas lowers indoor air quality and raises a variety of health concerns, researchers at the Lawrence Berkeley National Laboratory report.

Scientists found indoor pollution levels in many homes exceeded legal outdoor limits. In an article posted at Indoor Environment Connections, Dr. Brett Singer said, “If these were conditions that were outdoors, the Environmental Protection Agency would be cracking down. But since it’s in people’s homes, there’s no regulation requiring anyone to fix it.

“Reducing people’s exposure to pollutants from gas stoves should be a public health priority,” Singer added.

Researchers estimated that 60% of California homes where a gas stove was used for cooking at least once a week had indoor pollutant levels exceeding legal outdoor limits. The finding means that millions of people are subjected to levels of nitrogen dioxide, formaldehyde, and carbon monoxide in excess of current standards.

Performance of range hoods varied

Previously, Indoor Environment Connections said, researchers found range hoods varied widely in how effectively they remove pollutants. That study focused on seven models ranging in price from $40 to $650, with the “capture efficiency” of the units measured at less than 15% to more than 98%.

The hoods typically did a better job of capturing pollutants from the back burners than from the front of the stove. Hoods with grease screens and metal-covered bottoms didn’t do as well as those with open designs.

One hood was able to capture more than 80% of the pollutants from the front burners, but it was too loud to allow for normal conversation. That suggested to Singer that manufacturers could do better in their designs.

For more information on this topic, see Pollution in the Home: Kitchens Can Produce Hazardous Levels of Indoor Pollutants. Brett Singer’s full report is posted online: A Method to Estimate the Chronic Health Impact of Air Pollutants in U.S. Residences.

In a related project, Berkeley Lab researchers concluded the health consequences of poor indoor air quality “are as significant as those from all traffic accidents or infectious diseases in the United States.” Cooking was said to be a major contributor to the problem, not only because of the gas burners but also because of pollutants given off as foods are cooked.

17 Comments

  1. Eric Sandeen | | #1

    Which hoods worked?
    Is a summary of the findings of the Berkeley study available anywhere? It's a pity that the results of a study "funded by the California Energy Commission, the U.S. Department of Energy, the U.S. Department of Housing and Urban Development, and the U.S. Environmental Protection Agency" are behind a paywall.

  2. User avater GBA Editor
    Martin Holladay | | #2

    Response to Eric Sandeen
    Eric,
    The full report is posted online: A Method to Estimate the Chronic Health Impact of Air Pollutants in U.S. Residences.

  3. Nelson Labbe | | #3

    My worrying experience
    Earlier this year I measured carbon dioxide (CO2) levels while running our gas oven for almost an hour. The CO2 levels went from 500 ppm to 1,900 ppm, with the exhasut fan on! The CO2 levels in the bedrooms upstairs went to 1,700. I think that the OSHA recommended CO2 level is below 1,000 ppm. The CO2 levels in the kitchen didn't fall below 1,000 ppm until almost noon the next day. I'm also worried about the other pollutants such as carbon monoxide, nitorgen dioxide and formaldehyde. I wonder how much pollution we were exposed to around holidays when the oven and several burners would be on for hours a day.
    Thanks Scott for your post on this issue. We don't have a gas stove anymore, only because we were in the process of moving to a house doesn't have a gas stove, but I'm still concerned about those who do.

  4. User avater GBA Editor
    Martin Holladay | | #4

    Response to Jennifer Logue
    Jennifer,
    Thanks for your very helpful post, with the link to the full paper.

  5. Jennifer Logue | | #5

    If they are referring to our old EHP paper, it is publicly avai
    Hello all, I am the first author of this publication and it will be available for free.

    The one behind a pay wall is here:
    http://homes.lbl.gov/sites/all/files/a-method-to-estimate-the-chronic-health-impact-of-air-pollutants-in-us-residences-lbnl-report.pdf.

    All published works are publicly available from LBNL. The format is copy-written by the journal. but the content is public property and we make sure to publish it in a free, accessible format. There may be a slight delay between journal publication and publication on our website (this is because we want the LBL report to have the exact same content as the journal paper, so we don't publish the report until the final version of the paper is accepted). The link may not be in the article you read, but if you google the title, plus LBL you should get the link. If that is not the way you want to find it, you can go to the EETD publication site (http://eetd.lbl.gov/publications) and search for the title or the author. Finally, if you can't find the report, it is best just to email the first author. All of our email addresses are publicly available and we respond fairly quickly.

    1. Brian Schreiber | | #13

      I probably do not understand something but I read the following from the "paper" referred above as:
      Martin's response to Eric:

      The full report is posted online: A Method to Estimate the Chronic Health Impact of Air Pollutants in U.S. Residences.

      The following quote from the REPORT appears to hint at the severity of the problem:
      IAP = indoor air pollutants, IAQ = indoor air quality, DALY = Disability Adjusted Life Years

      "Conclusions: The demonstrated approach may be used to assess regional and national initiatives that impact IAQ at the population level. Cumulative health impacts from inhalation in U.S. residences of the IAPs assessed in this study are estimated at 400–1100 DALYs annually per 100,000 people." MY reading of this text implies that there are about 1000 life years(DALY's) penalty to be paid by 100,000 people annually in reduced life as a result of all this nasty indoor air quality. If that is a reasonable paraphrase then I divide the approx. 1000 DALY's [years] by 100,000 [people] and find a result of 0.01 years/ person or ===> 3.65 days per person penalty. So, this report tells us that bad IAQ causes the average person to last about 4 days less in his 78 year life span. Is this correct? What am I missing? What is the real meaning of Disability Adjusted?

  6. User avater GBA Editor
    Scott Gibson | | #6

    The study is available
    Good point. I followed up with Allan Chen at the Berkeley Lab, who contacted Jennifer Logue, an author of one of the studies. She explains the content of these reports is, in fact, free and public. You can find studies by searching the data base at the Lab's Environmental Energy Technologies Division. The full text of the report on the efficiency of kitchen fans is available here. But as you'll see, it does not mention the fans by brand.

  7. Eric Sandeen | | #7

    Thanks, all
    Thank you - I figured that the formatted paper was property of the journal, but I could not find any other copy. I appreciate the responses!

    Oh, and for Scott - on pages S-3 and later, they do actually identify fans by model number (BROAN 423001, QT230BL, QS330WW, QDE30SS, Air King ESDQ1303, Panasonic NN-­‐SD277BR, and Vent-a-hood PR9-­‐130)

  8. User avater GBA Editor
    Scott Gibson | | #8

    Thanks, Eric
    You're absolutely right.

  9. Kevin Dickson, MSME | | #9

    Are Good Cooking Smells Really Pollution?
    I would think if you don't often burn your food, then the air remains pretty healthy if you cook with electric. Water vapor is the most common byproduct of the actual cooking process.

  10. User avater
    Armando Cobo | | #10

    MUA Units
    Since the "TX Custom Home Code" requires all houses to have professional gas stoves, and the bigger the better, with exhaust fans from 1200-1500cfm, we've starting to use Fantech MUAS650 without the heaters. For the house MUA, we are using the Fantech FIT 120E ERV. Both units work great keeping low CO2s, and really easy to fit between roof trusses.
    (JIC, we receive no compensation form Fantech, though it would be nice if they throw us a free unit now and then)... ;-))

  11. Malcolm Taylor | | #11

    Armando,
    The "TX Custom Home Code". Haha. Nicely put!

  12. User avater GBA Editor
    Martin Holladay | | #12

    In Texas...
    Everything's bigger in Texas. Even the pressure imbalance when you turn on the range hood.

  13. Brian Schreiber | | #14

    Further perusing of Logue's paper indicates some things most perhaps have not read . . . between the lines, so too speak:
    -- The report is documentation for a proposed "methodology" that COULD be used for assessing impacts and for basing remedy's to poor IAQ. It is not a valid, direct assessment of TRUE estimates of impacts of any specific pollutant or toxic element. For example, this report cannot be used to predict the effect of 1900 ppm CO2 in the few hours per yr one is cooking without adequate kitchen exhaust.
    -- This report is an analysis of 77 OTHER reports, models, data synthesized from models as a means to offer its proposed methodology.
    -- Although it concludes some things that imply a LOSS in lost days of people's lives the uncertainty and the fact that it is based on OTHER reports and synthesis of reports data leaves a LOT to be desired as to the validity of using this to offer directives for action, for changes in how one does daily living etc. much less offering alternative solutions for improved kitchen exhaust that is anywhere near cost effective vs tradeoff in days of you life SAVED.

    From the document: "The aggregate data were used to calculate concentrations relevant to assessing chronic residential exposures to 267 chemical air pollutants. Seventy of the pollutants had sufficient toxicological and epidemiological data to calculate chronic health impact using the methodology described below, and were included in this study. They are listed in Table 1. Our analysis did not extend to contaminants from biological sources such as molds and allergens. We thus refer to the suite of pollutants considered as “non-biological”.
    This alone should give on pause when attempting to draw specific conclusions much less extrapolating this report to CO2, kitchen grease, degraded food aerosols floating off the frying pan!

    1. Malcolm Taylor | | #15

      Brian,

      I think the most helpful way to view this blog and the underlying research is, as you say, not to try and draw specific conclusions or extrapolate to other contaminants, but rather to realize that there is problem with particulates from cooking, that this is much worse with a gas stove, and that ventilation is necessary to deal with it.

      1. Brian Schreiber | | #16

        Sure Malcolm, I agree, for the most part, but others above ARE, in fact, all too willing to draw conclusions and extrapolate. . . For this reason I feel motivated to counteract those shrill cries and, therefore, offer the cautionary prose above.

        All the "Woe is me!" stuff and over concern about cooking with gas, to me, is pretty crazy.-- i.e. Mr. Labbe's input above. People have cooked with gas for a century now and it is a reasonable statement that most of those pooooor folks died from causes other than excess CO2, CO, and misc. oxides. Burning natural gas results in 2 parts water vapor and 1 part CO2-- mostly. Tiny levels of pollutants are generated too. . . CO, oxides, particulates .

        CO2, for example, is not directly toxic but simply displaces the amount of oxygen one takes in. CO, the only truly toxic product generated, is a TINY ratio of the various byproducts of combustion. The following constituents are generated from the combustion of natural gas, besides water: CO2, CO, Nitrogen oxides, Sulfur oxides, and particulates.

        The percentage of "pollutants" (only) in products of combustion:
        CO2-- 99.88% . . . uh, nearly 100%!
        CO-- 0.034%
        N-oxides-- 0.078%
        S-oxides-- 0.000008%
        Particulates-- 0.00006%

        1. Malcolm Taylor | | #17

          Brian,
          In some ways I agree, but I also don't think you need to die or even suffer permeant harm for indoor air quality to be problematic.

          I worked in commercial kitchen where the line-hood was not connected to the generator and didn't function during power outages. Within twenty minutes one chef was on the floor and the other didn't now what day of the week it was. Even high ambient CO2 levels, while not permanently debilitative, sure aren't something we should encourage. .

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