The Health Hazards of Natural Gas 
by Agnes Malouf and David Wimberly 
UPdate Summer 2001

     Thinking of cooking with gas? Think again.With natural gas rolling ashore in Nova Scotia, it is tempting to believe industry and government promises that if only we could plug into this rich new local resource we could see our fuel bills drop and free up money in the budget for the nicer things in life.
     But would we still feel the same way if we were to learn that, in trying to save those hard-earned dollars, we were undermining our health by polluting the air we breathe in our very homes? It may be discouraging to hear, but now is the time to listen to what the experts have to say before we make what may be the wrong decision for us and for our families.
     Living with natural gas can be a health hazard both for people who are healthy and for those who are already ill. It is especially risky for people who have weakened immune systems, including those who are asthmatic, allergic, or chemically sensitive.  Gas appliances create a constant low level exposure to gas which can 
cause or increase illnesses.  Natural gas is a sensitizer, which means that exposure can lead to intolerance and adverse reactions both to 
it and other substances in our environment.  
     The British medical journal, The Lancet, reported in1996 that the use of domestic gas appliances, particularly gas stoves, was linked to increased asthma, respiratory illness, and impaired lung function especially in young women.  Women using gas stoves had double the respiratory problems of women cooking on electric stoves. The same study showed that using extractor fans which vented the cooking fumes outside did not reduce adverse effects of gas. 
     The Canada Mortgage and Housing Corporation (CMHC) Clean Air Guide (1993) identified gas water heaters, furnaces, unvented space heaters and cook stoves as significant contributors to chemical contamination in the home. They recommended that gas appliances be replaced with electrical ones to reduce indoor air pollution.
 In a combined series of studies of 47,000 patients, two doctors found that "the most important sources of indoor pollution responsible for generating (environmental) illness were the gas cook stoves, hot water heaters, and furnaces" writes Dr. Bill Rea, of the Dallas Environmental Health Centre.
     "Traditionally natural gas is a pollutant chemical that can worsen both classical allergy and chemical sensitivity.  This effect has been seen mostly in areas where natural gas is in widespread use," wrote Dr. Gerald Ross, Past President of the American Academy of Environmental Medicine in1997.
     "For the chemically susceptible individual this gas may be the worst form of fuel," writes Dr. T. G. Randolph.  But surprisingly, his studies found that when gas stoves were removed from the home of a person with chemical sensitivities, not only did their health improve, but so did the health of all family members.
 Other studies have found that children living in homes with gas stoves had more than double the risk for respiratory symptoms, including asthma. Asthma patients who used a gas stove seven or more times a week were found to have doubled their risk of emergency room treatment. Infants who grow up in households with gas are almost twice as likely to develop childhood asthma as those who live with second-hand smoke. (Second hand smoke itself doubles a child's risk of developing asthma.) These studies have all been published in respected medical journals.
     When natural gas is burned, as in cooking and heating, the chemicals create nitrogen dioxide, carbon monoxide, fine particulates, polycyclicaromatic hydrocarbons, volatile organic compounds (including formaldehyde) as well as other chemicals. Just imagine what you are breathing when you bend over a gas cook stove to stir your food or when you open the oven door. This stuff sticks to your food, so you eat it as well. It sticks to clothes in gas dryers so you are covering your skin in it. It is lighter than air so it rises up into your living and sleeping areas, concentrating higher up nearer your head. This is one reason why gas is more of a health hazard than fuel oil which is heavier than air and thus sinks.
 It's been estimated that, when a typical gas oven and three burners are turned on, they release the same amount of combustion by-products as a typical gas water heater.  Regulations require that all gas water heaters (and gas furnaces) be connected to a chimney or a side vented directly outdoors. Not so for stoves. Gas driers are also not vented through chimneys, but through side vents.  Side vents are usually located low on buildings, and vented fumes can re-enter the living areas through windows, doors and cracks. 
     At a conference on air quality and children's health sponsored by the New Brunswick Lung Association, much attention was given to the respiratory problems caused by moulds.  Natural gas turns out to be a contributor to mould growth.
     One of the principal products of gas combustion is water vapour. Cooking with gas or burning gas in any way without perfect venting generates considerable amounts of moisture. When this moisture remains inside a building it is enough to be a significant contributor to moulds. This excess moisture also provides better growing conditions for dust mites, viruses and bacteria.
     Natural gas brings harmful chemicals into homes through the methane it contains. Methane (which  gives the flame its blue colour as it does in propane) is an asphyxiant. It typically contains impurities and additives including radon and other radioactive materials, BTEX (benzene, toluene, ethylbenzene and xylene), organometallic compounds such as methylmercury, organoarsenic and organolead. Mercaptan odorants  are also added to natural gas so that it can be detected by scent before reaching explosive levels.
     The components of the gas itself, as well as products of incomplete combustion including nitrogen diozide, carbon monoxide and others, have health implications individually and synergistically, as they combine with each other and with other indoor pollutants.
     "Natural gas is dangerous for several reasons," says health advocate Helen Lofgren .  "Even if you don't use the gas appliance, it is always there, leaking into the environment. It is dangerous for everybody, even those who do not notice its effects. If apartment buildings converted to gas stoves and water heaters, the total effect could be quite serious," Lofgren adds. "Unplanned leaks and the danger of explosion compound the risks of gas."
 Is there a safe way to use natural gas in the home? Yes and no. If you are going to use gas furnaces or water heaters, the adverse effects can be lessened considerably by putting them in a separate building downwind of the house with underground connections. Failing this, putting a state-of-the-art, totally sealed furnace and water heater in a separate sealed room with outside air intakes ducted directly into their combustion chambers, and automatic fans forcing exhaust up a chimney that extends above the roof line, will result in a substantial lessening of harmful effects.  No side venting should ever be allowed.  
     Even taking all these precautions, when combustion gases leaving a chimney cool they become heavier than air.  Depending on wind conditions, they can reenter the living space. And there is really no way at present to reduce the risk of gas appliances like stoves and clothes dryers. It is safest not to have any combustion at all inside the house.
     Natural gas hearings in Nova Scotia have looked at whether there should be a gas pipeline and who should own it.  But there has been no government assessment or public hearings into the health effects of home use of natural gas.
 Natural gas isn't all bad news. Using gas to fire up the generators that produce electricity to heat our homes and run our appliances and in large industrial settings makes environmental and economic sense.  Natural gas is a relatively clean-burning fuel and it is less polluting of our air than the coal and oil fuels we have traditionally burned.
     But let's keep it far away from the air we breathe inside our houses, apartment buildings and schools.  If we consider health care costs and the impact of living with illness, bringing natural gas into our homes is not a sensible choice.

For More Information:
Natural Gas websites: (note especially the Medical-Environmental Report) and

The Healthy Home Handbook: All You Need to Know to Rid Your Home of Health & Safety Hazards by John Warde, Random House Inc., 1997. 
Agnes Malouf is a teacher and is a member of the Board of the Nova Scotia Allergy and Environmental Health Association. 

David Wimberly is an environmentalist who has been concerned about the health hazards of natural gas for many years. He has made presentations on behalf of AEHA-NS and other organizations at several natural gas public hearings since1996. He can be reached by email at for additional information.