Indoor air pollution
We all know that smoking indoors will damage not only your own health but also that of every other household member. But did you also know that:
1. Heating your home with an unflued gas heater could expose you to high levels of dangerous air pollutants?
2. Adhesives and sealants used in many pressed-wood products could emit pollutants for years to come?
3. Many commonly used cleaning products and toiletries could give off a cocktail of air toxics? Indoor air pollution is increasingly recognised as one of the top five public health problems. In Australia, the CSIRO estimates it could cost us approximately $10 billion a year in health costs and lost production. This figure is only estimated because there’s little data available so far on the level of pollutants in Australian homes and the number of people affected.
Indoor air quality is expensive and difficult to measure — pollution levels can vary from time to time, from house to house, or even from one room to the next. But studies so far have established that some air pollutants are generally much more highly concentrated indoors than outdoors, particularly in new and newly renovated buildings, mobile homes, houses heated with unflued gas appliances, and in households where people smoke.
Despite our ‘outdoors’ image, Australians may spend 90% or more of our time indoors, where air pollution levels can be worse than outdoors.
Health effects
Just as varied as the range of potential indoor air pollutants are their health effects. Symptoms can be mild and non-specific such as headaches, tiredness or lethargy; similar to colds and flu such as irritated eyes, nose or throat; or more severe such as aggravation of asthma or allergic responses. They can even lead to respiratory diseases, cancer or death.
Not all pollutants’ health effects are well known, and even less is known about their cumulative effects or how they’ll compromise your health if you’re constantly exposed. People who are generally more sensitive to air pollutants include newborns and young children, elderly people, heart patients, people with bronchitis, asthma, hay fever or emphysema, and smokers. Some effects may show up soon after a single exposure, others only after years.
For specific health effects, check
Heating and cooking
Smoking
Inside your home
Biological allergens
Most homes have many sources of potential indoor air pollutants. Whether they’ll affect your health — and if so, to what degree — depends on many factors, such as the type of pollutant and level of exposure, your personal sensitivities, age and pre-existing medical conditions and the level of ventilation inside your home:
Except for the few cases where outdoor air pollutants cause problems indoors (say from car emissions if you live near a busy road), opening windows regularly can greatly improve the air quality inside. Good ventilation prevents air pollutants from building up and pushes them out of the room.
In some situations it may be best to leave windows open for most of the time you’re inside; in others, when you want a fast exchange of air, creating a draught by fully opening windows and/or doors for a few minutes might work best. If you ventilate this way when you’re heating, you’re wasting less energy than leaving a window ajar all the time.
Heating and cooking
To minimise our energy consumption and reduce greenhouse gas emissions, our efforts have concentrated in the past few decades on making houses more energy-efficient — at the expense of indoor air quality, it now transpires. The challenge now is to find ways of ensuring good indoor air quality while maintaining energy efficiency.
Unflued gas appliances
Heating with natural gas is popular in Australia. It’s widely available, comparatively cheap and valued for its lower impact on the environment — it emits far less of the greenhouse gas carbon dioxide than most of the electricity produced for heating. But unflued gas appliances can also be a major source of indoor air pollution.
These appliances have no flue or chimney to vent combustion particles and gases to the outside. It’s estimated around 600,000 Australian homes are heated with unflued gas heaters. So every winter, around two million people are potentially exposed to the two gas combustion pollutants of most concern:
Nitrogen dioxide (NO2) is a colourless and odourless gas that irritates the mucous membranes of the eyes, nose and throat and causes shortness of breath after exposure to high concentrations. Children and people with asthma and respiratory diseases are particularly at risk.
Carbon monoxide (CO) is equally hard to detect. It reduces the blood’s ability to carry oxygen to vital organs and is very poisonous at high levels. Symptoms of exposure include headache, tiredness, dizziness, nausea, confusion and shortness of breath. Exposure to high levels can even lead to death within minutes. Most susceptible are people with heart disease, smokers, young children and unborn babies.
Unflued gas heaters also release water vapour, which can contribute significantly to mould problems in poorly ventilated homes.
In good condition and properly used, unflued gas heaters only release small amounts of these pollutants, which aren’t likely to affect your health. But levels can build up with insufficient ventilation or if the heater is faulty, inappropriately installed, not serviced regularly or just old.
Older (pre-1990s) heaters are more likely to produce higher levels of nitrogen oxides (NOx) than newer ones that comply with pollutant emission limits set in the late 1980s. However, health and scientific experts still doubt that all associated health problems have been solved with these lower limits.
CSIRO tests of some new low-emission heaters found that some, while conforming to the Australian standard, still had NOx emissions about three times above the (lower) limit set by the World Health Organization. And those with low NOx emissions also released relatively high levels of formaldehyde.
In Victoria in 2000, five people died from CO poisoning from a gas heater: three in a caravan heated with an unflued gas heater and two in a room where a flued gas heater had a leaking flue. Two studies (one looking at unflued gas heating in homes, the other in schools) found that where there were higher levels of NO2, there were higher incidences of asthma symptoms and colds and sore throats respectively.
Solid fuel heating
Respirable suspended particles (fine particles, for short) are very small particles that almost behave like a gas you can inhale deep into your lungs. Depending on their type, size and your length of exposure, they can cause ill health or, in extreme cases, death.
The major sources of fine particles indoors are wood and kerosene heaters and environmental tobacco smoke. They can escape from poorly installed or badly maintained solid fuel heaters, from leaks in the flue or from opening the heater door for refuelling.
In Australia, a study found particularly high levels of fine particles in households where people smoked and where solid fuel was used for heating.
Tips for cleaner indoor air
Ensure good ventilation whenever you use an unflued gas heater.
In some states, you can only install an unflued gas heater if the heater and your room space meet certain conditions — check with your local gas supplier.
Don’t use it in a confined space for long periods of time and never in a small room such as a bedroom, bathroom or caravan.
Never use it if it releases a strange smell or if it gives you uncharacteristic headaches or nausea.
Have it serviced at least every two years.
Turn the heater off while you’re using a gas cooker in the same room (and don’t use a gas cooker to heat a room) otherwise the gas combustion pollutants can build up to well above ‘safe’ levels. Use a rangehood that’s vented outside or open a window while cooking.
If you notice a persistent yellow-tipped flame on your gas stove, it could be releasing higher pollutant emissions. Ask your gas provider, plumber or gasfitter to adjust the burner so the flame is blue.
Carbon monoxide levels can also pose problems indoors if your garage is attached to the house. So keep the connecting door closed when you leave and arrive with the car, and never leave the car (or a petrol lawnmower) running inside the garage.
This article was last reviewed in August 2003.
Smoking
Environmental tobacco smoke (ETS) is a major contributor to indoor air pollution. It’s a mixture of gases and fine particles containing around 4000 chemicals, including 43 that are known to cause serious health problems, including cancer, in humans.
Some of the air pollutants in ETS include carbon monoxide, formaldehyde, respirable suspended particles and nitrogen dioxide.
ETS causes eye, nose and throat irritation and may affect the cardiovascular system. Babies and children and anyone with asthma are particularly at risk of respiratory infections and irritations.
Smoking indoors can increase the level of respirable particles to more than 10 times the outdoor level. In Australia, the ban on smoking in public buildings should have reduced fine particle concentrations there, but it can still be a problem in private homes.
Tips for cleaner indoor air
Don’t smoke indoors or let others do so.
This article was last reviewed in August 2003.
Inside your home
If you’re lucky enough to move into a brand-new home this year, put good ventilation at the top of your agenda, as many of the commonly used construction products can release air toxics in high concentrations — and many are likely to remain at high levels for weeks or months to come. Of most concern to human health are formaldehyde and volatile organic compounds (VOCs).
Formaldehyde
This colourless, pungent-smelling gas is emitted by gas stoves and in tobacco smoke. But the most likely source for high levels indoors are common building products such as medium-density fibreboard (MDF), plywood and particleboard. The resins used in their manufacture can release formaldehyde gas for many years. Emissions usually decrease over time and are highest in new or newly renovated buildings.
Formaldehyde can irritate the eyes, nose, throat and lungs. It can cause cancer in animals and may cause it in humans. High exposure can cause breathing difficulties and trigger attacks in people with asthma.
In Australia, high formaldehyde levels have been found in mobile homes and caravans (which contain many pressed-wood products and can be poorly ventilated), and in buildings that had recently been insulated with urea-formaldehyde foam insulation (UFFI), but levels there decreased after several months when the foam had dried.
Australian-made ‘low-emission’ pressed-wood products are claimed to release less formaldehyde than some imported products. In one case, though, CSIRO tests found their emissions to be about twice as high as the European low-emission specifications.
Volatile organic compounds (VOCs)
The term VOCs covers a great range of compounds, among them benzene, toluene, chlorofluorocarbons, halons, carbon tetrachloride and some pesticides. In any building you may find as many as 150 of these carbon-containing chemicals which often have an odour and evaporate at room temperature.
Floor coverings such as carpets, tiles and polished wood (or the adhesives, varnishes and paints used to lay and seal them) often contain VOCs, as do cleaning fluids and polish, textile finishes, scents, sprays and tobacco smoke.
Only a few VOCs have been studied in detail and little is known about their cumulative health effects when mixed with other air pollutants. Many are known to cause cancer in animals and some to cause it in humans. Symptoms of excessive VOC exposure include eye, nose, throat and skin irritation, headache, vomiting, drowsiness, visual disorders and memory impairment.
In Australia a recent CSIRO study found higher indoor VOC levels in established buildings compared to outdoor levels, and very much higher levels in new homes.
Lead and asbestos
Old houses can also harbour indoor air pollutants that can pose a health hazard when renovating. Lead and asbestos were both widely used building materials in the past — lead in paints (before 1970) and asbestos in products such as asbestos-cement sheets and roofing sheets, textured paint, vinyl floor tiles, pipe lagging and fire-resistant boards (before the mid 1980s).
Lead paint and asbestos-containing materials pose no danger when intact and left alone, but when disturbed or removed can release fine particles you can breathe in or swallow.
In the body, lead can harm virtually every system, particularly the brain, kidneys and reproductive organs. Children under four and pregnant women are most vulnerable.
Because the health risks associated with asbestos exposure are well known (they include lung cancer, mesothelioma and asbestosis), asbestos is no longer allowed in building products for the home and will be prohibited in all forms from December 31, 2003.
Tips for cleaner indoor air
Ensure good ventilation after moving into a new or newly renovated home.
Reduce the number of products you use that contain VOCs and choose low-emission alternatives whenever possible. For example, use flyscreens or mosquito nets rather than insect sprays. And if you must use indoor pesticides on a large scale, avoid spills, leave the building for a few hours afterwards and ventilate well.
Limit your use of spray toiletries and strong-smelling cleaning products in non-ventilated areas.
Before putting away dry-cleaned clothes, air them well outside or in a well-ventilated room you’re not using.
The same advice applies to new, freshly lacquered or oiled furniture than can emit VOCs, especially when individual pieces are packed airtight in the factory for you to assemble at home.
Take special care when you strip old paint or clean walls with flaking paint that could contain lead. Contact your health department or lead advisory service for advice on how to remove it safely, or get a professional to do the job.
Don’t rip, cut, sand or remove asbestos-containing materials — your health department can give advice on sealing, enclosing or removing the source.
Consider using materials that are by nature non-emitting, such as wood, bricks, glass, granite/stone, powder-coated or finished metals or stainless steel.
Look for ‘low-emission’ pressed-wood products — the CSIRO has a list of useful websites you may want to consult if you’re after low-emission products certified by overseas labelling schemes
Have joinery done without the use of solvents and caulking compounds.
Finish surfaces with water-based or low-emission (‘zero-VOC’) coatings.
Ensure good ventilation (open windows and use a fan) when painting.
When buying a new carpet, ask the retailer for information about lower-emission carpets and underlay, and ask them to unroll and air it before it’s laid. Ensure good ventilation afterwards.
This article was last reviewed in August 2003.
Biological allergens
Biological allergens (allergy-causing substances) can cause health problems for the 20–40% of us who are sensitive to them. Allergic reactions occur only after repeated exposure to a specific biological allergen, so even if you haven’t had problems in the past, you may suddenly become very sensitive to them.
Dust mites, pets and pollen
Of most concern in the Australian context are house dust mites, given our high asthma rates. But other animal allergens (from cats, dogs, birds or even cockroaches) can also spell problems for some people.
The allergens are usually contained in the animal’s droppings, saliva or dander (tiny skin scales) and can become airborne when small particles dry and fall off. In people sensitive to them, inhaling these allergens can trigger a reaction in the lungs (asthma), nose (hay fever or allergic rhinitis) or skin (dermatitis or eczema).
And on warm days, when you leave doors and windows open, the small airborne pollen grains most grasses, trees and shrubs release can cause similar reactions in people sensitive to these allergens.
Moulds and fungi
These are fine, often invisible filaments whose spores become airborne and can be inhaled. Damp areas in the house (such as bathrooms, cellars and poorly ventilated rooms) are particularly susceptible to mould and fungal growth, as are water-damaged carpets and building materials. Unflued gas or kerosene heaters can also contribute to mould problems because of the water vapour they release.
In people sensitive to mould spores, inhaling them can cause various allergic reactions. Mould can also produce poisons known as mycotoxins which, when absorbed, can sometimes affect the nervous system. Some fungi can also infect various parts of the body, particularly the lungs and skin.
Tips for cleaner indoor air
If you’re allergic to dust mites, contact your local Asthma Foundation for comprehensive advice on how to reduce your exposure. Basic advice includes using bedding that can be washed in hot water and/or dust mite-proof covers, and avoiding furnishings and carpets that accumulate dust.
Vent your clothes dryer and rangehood to the outside.
When showering, bathing, cooking, washing or using a clothes dryer, open windows (or use an exhaust fan or rangehood) so the steam won’t settle inside.
Keep your house warm and dry.
If you’re sensitive to animal allergens but don’t want to live without a pet, keep it out of living and sleeping areas.
This article was last reviewed in August 2003.
Cars and buildings
New cars
Indoor air pollutants can also lurk in new cars, especially in the first six months after manufacture. When the CSIRO assessed three new cars from different manufacturers, it found very high VOC levels that could even pose a safety problem, as they can irritate the senses and impair performance and memory.
BRI and SBS
‘Building-related illness’ is a clinically diagnosed illness directly related to exposure to indoor air pollutants — the symptoms can be traced to a specific pollutant in a building.
‘Sick building syndrome’ refers to a set of symptoms a number of people inside a particular building suffer chronically, which disappear when they’re out of that building. These symptoms can’t be traced to a specific pollutant.
This article was last reviewed in August 2003.
More information
In Australia, no central authority is responsible for indoor air — national, enforceable standards only apply to workplace and outdoor air environments. But Commonwealth and state and territory governments are working with organisations such as the CSIRO, NHMRC, Standards Australia and the Gas Association to formalise regulations to improve indoor air quality.
Control at the source is generally seen as the most important strategy for achieving it. A few voluntary industry initiatives have started tackling some of the problems with the development of lower-emission building products and gas heaters.
If you want more information on indoor air pollution, check the following links:
Environment Australia has compiled a State of Knowledge report on indoor air pollution.
The Commonwealth Department of Health and Ageing has published the comprehensive brochure Healthy Homes: a guide to indoor air quality in the home for buyers, builders and renovators. Download it here.
If you think the air quality in your home is affecting your health but you can’t pinpoint the source, the CSIRO can assess your indoor air for a cost of $1500–$3500 upwards. Contact the business development manager.
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