Cooks love their gadgets, from countertop slow cookers to instant-read thermometers. Now, there’s increasing interest in magnetic induction cooktops(電磁感應爐) – surfaces that cook much faster than conventional stoves, without igniting a flame or heating an electric coil.
Some of this attention is overdue: Induction has long been popular in Europe and Asia(在歐亞流行), and it is more energy-efficient than standard stoves. But recent studies have also raised concerns about indoor air emissions from gas stoves.
Academic researchers(學術研究人員) and agencies such as the California Air Resources Board have reported that gas stoves can release hazardous air pollutants(煤氣爐釋放有害空氣污染物) while they’re operating, and even when they’re turned off.
As an environmental health researcher who does work on housing and indoor air, I have participated in studies that measured air pollution in homes and built models(建造室內空氣汙染的測量和計算模型) to predict how indoor sources would contribute to air pollution in different home types. Here is some perspective on how gas stoves can contribute to indoor air pollution, and whether you should consider shifting away from gas.
對呼吸道的影響：One of the main air pollutants commonly associated with using gas stoves is nitrogen dioxide(二氧化氮), or NO₂, which is a byproduct of fuel combustion(燃燒的產物). Nitrogen dioxide exposures in homes have been associated with more severe asthma(比較嚴重的哮喘) and increased use of rescue inhalers(增加的呼吸救援需要) in children. This gas can also affect asthmatic adults, and it contributes to both the development and exacerbation of chronic obstructive pulmonary disease(發展和惡化慢性阻塞性肺病).
Nitrogen dioxide in homes comes both from outdoor air that infiltrates indoors and from indoor sources. Road traffic is the most significant outdoor source(NO2來自室外交通的排放); unsurprisingly, levels are higher close to major roadways. Gas stoves often are the most substantial indoor source(和室內的煤氣爐), with a greater contribution from large burners that run longer.
The gas industry’s position is that gas stoves are a minor source of indoor air pollutants. This is true in some homes, especially with respect to exposures averaged over months or years.
But there are many homes in which gas stoves contribute more to indoor nitrogen dioxide levels than pollution from outdoor sources does, especially for short-term “peak” exposures during cooking time. For example, a study in Southern California showed that around half of homes exceeded a health standard based on the highest hour of nitrogen dioxide concentrations, almost entirely because of indoor emissions(半數住家在烹調排放NO2濃度最高的時段超過健康標準).
How can one gas stove contribute more to your exposure than an entire highway full of vehicles? The answer is that outdoor pollution disperses over a large area, while indoor pollution concentrates in a small space.
How much indoor pollution you get from a gas stove is affected by the structure of your home, which means that indoor environmental exposures to NO₂ are higher for some people than for others. People who live in larger homes, have working range hoods that vent to the outdoors and have well-ventilated homes in general will be less exposed than those in smaller homes with poorer ventilation(寬敞和通風排氣好的住家較少受NO2汙染的影響).
But even larger homes can be affected by gas stove usage, especially since the air in the kitchen does not immediately mix with cleaner air elsewhere in the home. Using a range hood when cooking, or other ventilation strategies such as opening kitchen windows, can bring down concentrations dramatically.
甲烷和其它有害空氣汙染物: Nitrogen dioxide is not the only pollutant of concern from gas stoves. Some pollution with potential impacts on human health and Earth’s climate occurs when stoves aren’t even running.
A 2022 study estimated that U.S. gas stoves not in use emit methane – a colorless, odorless gas that is the main component of natural gas – at a level that traps as much heat in the atmosphere as about 400,000 cars(估計美國的煤氣爐不燃燒時所洩漏的甲烷相當於40萬輛汽車所排放的CO2).
Some of these leaks can go undetected. Although gas distributors add an odorant(煤氣中加氣味劑) to natural gas to ensure that people will smell leaks before there is an explosion risk, the smell may not be strong enough for residents to notice small leaks.
Some people also have a much stronger sense of smell than others. In particular, those who have lost their sense of smell – whether from COVID-19 or other causes – may not smell even large leaks(有些人嗅覺不好，聞不到洩漏的煤氣). One recent study found that 5% of homes had leaks that owners had not detected that were large enough to require repair.
This same study showed that leaking natural gas contained multiple hazardous air pollutants, including benzene, a cancer-causing agent(致癌的苯). While measured concentrations of benzene did not reach health thresholds of concern, the presence of these hazardous air pollutants could be problematic in homes with substantial leaks and poor ventilation.
為健康和氣候變化而換爐：So, if you live in a home with a gas stove, what should you do and when should you worry? First, do what you can to improve ventilation(立即改善通風), such as running a range hood that vents to the outdoors and opening kitchen windows while cooking. This will help, but it won’t eliminate exposures, especially for household members who are in the kitchen while cooking takes place.
If you live in a smaller home or one with a smaller closed kitchen, and if someone in your home has a respiratory disease like asthma or chronic obstructive pulmonary disease, exposures may still be concerning even with good ventilation. Swapping out a gas stove for one that uses magnetic induction would eliminate this exposure while also providing climate benefits.
There are multiple incentive programs to support gas stove changeovers, given their importance for slowing climate change. For example, the recently signed Inflation Reduction Act(降低通漲法令) of 2022, which includes many provisions to address climate change, offers rebates for the purchase of high-efficiency electric appliances(提供購買高效電器的回扣) such as stoves.
Dozens of U.S. cities have adopted or are considering regulations that bar natural gas hookups in new-construction homes(新建房屋禁止安裝煤氣管道) after specified dates to speed a transition away from fossil fuels. At the same time, at least 20 states have adopted laws or regulations that prohibit bans on natural gas.
Moving away from gas stoves is especially important if you are investing in home energy efficiency measures(投資在家用節能電器), whether you are doing it to take advantage of incentives, reduce energy costs or shrink your carbon footprint. Some weatherization steps can reduce air leakage to the outdoors, which in turn can increase indoor air pollution concentrations if residents don’t also improve kitchen ventilation.
Even if you’re not driven to reduce your carbon footprint – or you’re just seeking ways to cook pasta faster – the opportunity to have cleaner air inside your home may be a strong motivator to make the switch. (本文取自專家資訊網站Conversation Jonathan Levy教授的文章。)
No comments:
Post a Comment