Gas stoves can spew lots of pollution, even when they’re turned off

atmosphere: The envelope of gases surrounding Earth, another planet or a moon.

benzene: A ring-shaped hydrocarbon molecule made from six carbon and six hydrogen atoms. It’s liquid at room temperature and easily evaporates into the air. It’s widely used in industry and a natural constituent of petroleum, gasoline and cigarette smoke. It is highly toxic if breathed in large amounts and may cause cancer after prolonged, lower dose exposure.

chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H₂O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

chemical reaction: A process that involves the rearrangement of the molecules or structure of a substance, as opposed to a change in physical form (as from a solid to a gas).

coauthor: One of a group (two or more people) who together had prepared a written work, such as a book, report or research paper. Not all coauthors may have contributed equally.

develop: To emerge or to make come into being, either naturally or through human intervention, such as by manufacturing.

engineer: A person who uses science to solve problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need. (v.) To perform these tasks, or the name for a person who performs such tasks.

environmental engineer: A person who uses science to study and solve problems in ecosystems — from forests to the human body.

environmental science: The study of ecosystems to help identify environmental problems and possible solutions. Environmental science can bring together many fields including physics, chemistry, biology and oceanography to understand how ecosystems function and how humans can coexist with them in harmony. People who work in this field are known as environmental scientists.

exhaust: (in engineering) The gases and fine particles emitted — often at high speed and/or pressure — by combustion (burning) or by the heating of air. Exhaust gases are usually a form of waste.

fossil fuel: Any fuel — such as coal, petroleum (crude oil) or natural gas — that has developed within the Earth over millions of years from the decayed remains of bacteria, plants or animals.

fracking: Short for hydraulic fracturing. It’s a process that involves pumping liquid at high pressure underground to crack open rocks, especially to extract natural gas. Those cracks are then held open by sand that had been added to the fracking fluid.

fuel: Any material that will release energy during a controlled chemical or nuclear reaction. Fossil fuels (coal, natural gas and petroleum) are a common type that liberate their energy through chemical reactions that take place when heated (usually to the point of burning).

function: The specific role some structure or device plays. (in math) A relationship between two or more variables in which one variable (the dependent one) is exactly determined by the value of the other variables.

greenhouse gas: A gas that contributes to the greenhouse effect by absorbing heat. Carbon dioxide is one example of a greenhouse gas.

hydrocarbon: Any of a range of large molecules containing chemically bound carbon and hydrogen atoms. Crude oil, for example, is a naturally occurring mix of many hydrocarbons.

magnetic field: An area of influence created by certain materials, called magnets, or by the movement of electric charges.

mechanical engineer: Someone trained in a research field that uses physics to study motion and the properties of materials to design, build and/or test devices.

methane: A hydrocarbon with the chemical formula CH₄ (meaning there are four hydrogen atoms bound to one carbon atom). It’s a natural constituent of what’s known as natural gas. It’s also emitted by decomposing plant material in wetlands and is belched out by cows and other ruminant livestock. From a climate perspective, methane is 80 times more potent than carbon dioxide is in trapping heat in Earth’s atmosphere, making it a very important greenhouse gas.

natural gas: A mix of gases that developed underground over millions of years (often in association with crude oil). Most natural gas starts out as 50 to 90 percent methane, along with small amounts of heavier hydrocarbons, such as propane and butane.

nitrogen: A colorless, odorless and nonreactive gaseous element that forms about 78 percent of Earth’s atmosphere. Its scientific symbol is N. Nitrogen is released in the form of nitrogen oxides as fossil fuels burn. It comes in two stable forms. Both have 14 protons in the nucleus. But one has 14 neutrons in that nucleus; the other has 15. For that difference, they are known, respectively, as nitrogen-14 and nitrogen-15 (or ¹⁴N and ¹⁵N).

nitrogen dioxide: A gas ­— often abbreviated as NO₂ — that has become an important pollutant in urban air. Most of this gas in the Earth’s lower atmosphere has been released by human activities. Gasoline- and diesel-fueled vehicles are among the most common sources of NO₂ in cities. Coal- and natural-gas-burning power plants also can emit regionally high amounts. This pollutant can cause breathing problems and aggravate lung-related diseases such as asthma. Nitrogen dioxide is among the pollutants that contribute to the formation of smog and acid rain.

oxygen: A gas that makes up about 21 percent of Earth’s atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).

pollutant: A substance that taints something — such as the air, water, our bodies or products. Some pollutants are chemicals, such as pesticides. Others may be radiation, including excess heat or light. Even weeds and other invasive species can be considered a type of biological pollution.

potent: An adjective for something (like a germ, poison, drug or acid) that is very strong or powerful.

risk: The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)

symptom: A physical or mental indicator generally regarded to be characteristic of a disease. Sometimes a single symptom — especially a general one, such as fever or pain — can be a sign of any of many different types of injury or disease.

technology: The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.

toxic: Poisonous or able to harm or kill cells, tissues or whole organisms. The measure of risk posed by such a poison is its toxicity.

vent: (n.) An opening through which gases or liquids can escape.

World Health Organization: An agency of the United Nations, established in 1948, to promote health and to control communicable diseases. It is based in Geneva, Switzerland. The United Nations relies on the WHO for providing international leadership on global health matters. This organization also helps shape the research agenda for health issues and sets standards for pollutants and other things that could pose a risk to health. WHO also regularly reviews data to set policies for maintaining health and a healthy environment.