Combustion Products

Combustion Products

Burning fossil fuel creates indoor air pollution

Do you or someone in your household experience regular and unexplained flu-like symptoms? Of course, the reason for this may be just another bout of the common cold; or it may be a reaction to poor indoor air quality. In the order of importance, the by-products of burning fossil fuels come just after tobacco smoke as a major source of harmful pollution.

When you add excessive heat to a substance, such as rubbing a match stick on the rough side of the match box, it may begin to react violently with other chemicals. The reaction creates even more heat that sometimes can’t dissipate quickly enough into the air and, therefore, shows itself as a flame or even explosion. In our case, the chemicals in the fuel you use for heating or cooking react with the chemicals in the air – hopefully not too violently, but enough to produce a flame. The reaction is so quick, that the chemicals aren’t very choosy about the type and number of other chemicals they need to combine with.

A carbon atom, the main ingredient of fossil fuels, for example, may react with one or two oxygen atoms. The ‘mono’ in monoxide stands for ‘one’ or ‘single,’ i.e. the carbon combines with only one oxygen atom during the burning process, simply because there aren’t enough oxygen atoms available in an improperly operating appliance. In a well-maintained appliance enough air is available and the carbon can react with two oxygen atoms and produce the harmless carbon dioxide (‘di’ for two). The gas in the bubbles of your soft drink is carbon dioxide. The chemical formulas show you the difference: combine one atom of carbon (C) with one atom of oxygen (O) and you get carbon monoxide (CO). Do the same with two oxygen atoms and you get carbon dioxide (CO2).

wood_stoveMost homes do have one or more appliances that burn gas, oil, kerosene, coal or wood for cooking and heating purposes. For some home owners, however, an open fire or scented candle is nothing but fashion or decoration. Major appliances are usually vented to the outside, but smaller, unvented devices release their exhaust gases straight into the room. Do you always use the kitchen fan or range hood when you cook your meal over a gas flame? That is, if you have one at all, or perhaps it is too noisy. Many families around the world still cook on unvented stoves that are wood or coal-fired.

The outside air may follow Santa Clause’s example and come in through the chimney.

Unvented appliances contribute all their exhaust gases to indoor air pollution, but problems may also arise with improperly maintained vented appliances. Modern homes are very well ‘weatherized.’ That means outside air finds it hard to penetrate sealed windows and doors when there is lower air pressure inside. The outside air may follow Santa Clause’s example, however, and come in through the chimney. The pressure differences allows the so-called ‘backdraught’ to overcome the draught of the chimney or flue. On such occasions your guests will cough and rub their eyes and your new fireplace may be more of an embarrassment than a source of pride. A much more obvious reason for a backdraught is, of course, a blocked or partially blocked flue. But a less obvious reason is the stealthy escape of combustion gases through cracked or poorly maintained and installed ventilation systems.

The appliance itself can be at fault as well. Appliances need maintenance. Does the flame get enough air to burn efficiently, and is the burner still functioning as it is designed to do? Be honest, since you bought the heater or stove, perhaps many years ago, has it had professional maintenance? I’m guilty of neglect myself at times. The last thing on my mind is to call a plumber to have my gas heater inspected. “I will get around doing it soon,” that’s what I say.

Easy to forget are pollutants that are forced into your home from outside. No, not industrial pollution, as this would be beyond the subject of this book. I’m talking about home-made outside air pollution.

For example, your garage may be attached to your house or under the same roof. Brickwork is never airtight, especially if there are water pipes or electric cables in the adjoining walls, and garage fumes may enter the living area. If not the garage, perhaps you have a hobby room or garden shed nearby from where lawn mower fumes and woodburnig or soldering gases may drift into your home.

What substances make combustion products so harmful? The major hazardous components are carbon monoxide (CO), nitrogen and sulphur dioxide (NO2, SO2) and microscopic particles (particulate matter). The burning process releases a variety of other gases as well, which can also be very harmful to your health, in particular if the wood you are burning contains additives such as arsenic-based timber treatments.

Health Effects of Combustion Products

We know that the health effects of combustion products can be very subtle at first. Accidents aside, the pollutants can give us a simple headache, may lead to lung disorders, and in extreme cases death. Alright the latter isn’t quite so subtle. But when you consider that over 1,000 carbon monoxide deaths occur in the US every year, then the extreme cases aren’t so rare either.

The effects can be immediate, but health problems may not show up for many years. What the effect will be like, depends on whether a person is particularly susceptible to combustion pollutants, what type and the amount he or she was exposed to and, of course, how long the exposure lasted. As you can imagine, someone with an existing lung disorder, for example, is very likely to suffer more than a healthy person does. In the following I will show you the health problems associated with the most common combustion pollutants.

Carbon Monoxide Poisoning

What has no color, no taste, no odor, and is poisonous? That is an inappropriate question at this point, as the heading of this chapter gave away the answer already. The burning of organic material, such as wood, coal, gas, kerosene, oil, produces carbon monoxide (CO) amongst other gases. The amount is very little if the appliances are well maintained, but if the appliances operate improperly and restrict the flow of air towards the flame or the fire, then the CO concentration in your room can become fatal. Engine exhausts may also contain a large proportion of carbon monoxide, which can enter your home from an attached garage.

Carbon monoxide is a poison that, in high enough concentrations, will suffocate a person.

The gas is responsible for many suicidal and accidental deaths. When you inhale the gas, the lungs will release it into your blood stream where it will attach to hemoglobin. Hemoglobin is the red protein in your blood that is responsible for carrying oxygen to every part of your body, including vital organs and the brain. Hemoglobin finds it much easier to combine with carbon monoxide than with oxygen, though. When carbon monoxide replaces between 30% to 40% of the oxygen, a person may develop a headache, is nauseated or vomits, feels dizzy and is confused. People with chronic heart disease may experience increased chest pain. Body parts with high oxygen needs, such as the heart muscles and the brain, are the first affected. A level of above 60% may lead to unconsciousness and death after prolonged exposure. Infants, the elderly, and people with a low hemoglobin level and with heart or respiratory disorders may react to much lower levels.
Carbon monoxide poisoning

The mechanism of how carbon monoxide replaces oxygen also provides the answer for emergency treatment – provide oxygen. If you or someone in your family shows any of the symptoms, turn off suspected appliances, get into fresh air immediately, then seek professional treatment. Unfortunately, this is the easy part. The hard part is to recognize that carbon monoxide poisoning is the cause before it is too late. As mentioned earlier, you can’t see or smell the gas and the symptoms are similar to common illnesses. Nevertheless, it will help your doctor in the diagnosis when you tell him or her that you suspect carbon monoxide poisoning.

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