Indoor Air Quality Testing Guide: Cost & Contractors

Indoor air quality testing is essential to make sure your family does not suffer any possible harmful effects of pollutants you may have at home. Find out the cost of testing indoor air.

Everyone is concerned about the outside air quality in our towns and cities. Vehicle exhaust fumes, garden refuse fires and smog; all these and more are the subject of rigorous debate in national and state government as well as local and neighbourhood issues. But how many people know anything about the problems of air quality in the home? I expect it’s not many. We probably spend most of our life indoors, whether it is at school or work, relaxing in the evening or sleeping at night so doesn’t it make sense to keep the quality of air inside our homes as good as we would hope for outside. After all we may not be able to change the quality of the outside air but we certainly can have a go at improving the air inside our own homes.

What problems can interfere with the quality of your air?

For the purposes of this article we won’t worry about the problems of outdoor quality. We will assume we live in an enclosed box that has its own separate air supply. We won’t worry about what happens at work or school because we cannot really affect these places, they come under the jurisdiction of others. What we are really worried about are those factors that are inherent in our own homes.

So what are these factors and what can we do about them? If we can’t do anything ourselves, can we employ a professional to do the job for us? If so, then how much will it cost? First of all let’s list the factors and then expand on each of them and see what we can do.

  • Asbestos
  • Mould
  • Lead based paint
  • Humidity
  • Radon
  • Second hand smoke
  • Combustion pollutants
  • Volatile organic compounds
  • Asthma triggers


This substance at one time was thought to be the wonder building material. Asbestos occurs naturally in the ground as a set of six silicate minerals. Their structure is in the form of thin fibrous crystals. Each fibre that you can see is made up of millions of microscopic fibrils that are released into the air through mechanical abrasion amongst other processes. Asbestos has been mined for more than 4000 years but it became the ‘must have’ building material at the end of the nineteenth century when people began to notice its useful physical properties.

The best of the mineral’s properties being:

  1. Sound absorption
  2. Tensile strength
  3. Affordability
  4. Fire resistance
  5. Heat insulation
  6. Electrical insulation

Unknown to a lot of people (or disregarded by the few) were the harmful effects upon the human body when asbestos was inhaled; lung cancer, asbestosis and mesothelioma. It wasn’t until the 1990s that asbestos was finally banned.

Use of asbestos was extremely widespread but the harmful aspects of asbestos only come into play when the substance is disturbed and the microscopic fibrils are released. For this reason asbestos is still found in older buildings where it does its job often unknown to the occupants. Once the substance is noticed and the presence of fibrils ascertained (by damage or wear and tear) the substance has to be removed by a qualified and licenced removal company and disposed of at a licenced site.

If you live in a house that was built before the 1980s it is quite possible that you have asbestos somewhere in your home whether you like it or not. If you have asbestos then you almost certainly have the tiny fibrils floating in the air and being inhaled.

There are strict rules concerning the presence, identification and removal of asbestos in most countries but this article is not the place to go into these. If you are in any doubt as to whether you have asbestos in your home you must hire a company to identify and remove the substance for you.


These are living plants that produce spores. The spores float in the air and adhere to damp surfaces where they start to grow. The obvious damp surfaces that will affect humans are the mucus membranes around the eyes, nose, mouth and respiratory system.

If molds are inhaled or touched they can cause the body to react with symptoms similar to hay fever caused by pollen. Typical symptoms include sneezing, runny nose, sore eyes and rashes. Moulds and pollen can also trigger asthma attacks.

You will never remove spores or pollen from the air, they are everywhere. Normally they are quite harmless but if the mould starts growing indoors in damp places then the concentrations can rise and the classic symptoms start to be seen. The best way to prevent mould growth is to control the moisture in the home. Dehumidifiers and air conditioning are two obvious methods to solve this problem.

Lead Based Paint

Lead has been recognised for many years as a harmful pollutant of the environment. Lead used to be very common as an additive in ordinary household paints until 1978. Although no new lead based paint has been used since then there are still many houses that have their indoor and exterior surfaces finished with this kind of paint. There are many ways in which lead can be ingested, the most notable being that of children putting painted items into their mouths. This however is not really relevant to today’s article; we are more concerned with how lead based paint can affect indoor air quality.

Normally lead based paint is quite safe until it starts to have mechanical wear and tear and the paint starts to chip and produce dust or when the paint is improperly removed and dust is produced by sanding, scraping and open flame burning.

When lead is ingested by whatever means into the human body it is distributed throughout the body using the circulatory system (the blood). The lead starts to accumulate in the:

  • Bones
  • Nervous system
  • Kidneys
  • Immune system
  • Reproductive system
  • Developmental system
  • Cardiovascular system

Lead also affects the capacity for the blood to carry oxygen around the body.

Obvious symptoms in children include:

  • Learning problems and low IQ
  • Behavioural problems and hyperactivity
  • Reduced growth rate
  • Deafness
  • Anaemia

Excessive lead exposure can cause seizures, unconsciousness and death.

Ways to reduce lead exposure from the air:

✓ Inspect and maintain all painted surfaces and restore any that have signs of deterioration.

✓ Keep the home dust free by using a HEPA filter vacuum cleaner.

✓ Clean areas where paint receives friction wear, producing dust. This is usually windows, doors and drawers. Wipe these areas with a damp rag or sponge to remove dust and paint chips.

✓ If you are having renovations or painting done in the house make sure the contractor is Lead Safe Certified.


Relative humidity is the fraction (expressed as a percentage) of water vapour in the air at a given temperature compared with the maximum amount of water vapour the air is capable of holding at that temperature. So, if the air is holding as much water vapour as it is able then it is said that there is 100% humidity.

The optimum indoor humidity level is reckoned to be in the range of 30% to 50%. If the indoor humidity level is higher than 60% then the conditions are favourable for the growth of mould and mildew with the adverse effects on health that these produce.

If the indoor relative humidity is below 30% there is once again a risk of health problems, but this time due to the mucus membranes drying out and lowering the body’s resistance to respiratory diseases.

Air quality due to humidity is measured in air changes per hour (ACH). Older houses tend to have a lower ACH value whose average is about 1 to 2. Newer houses have an ACH value of about 5. Remember that if the ACH value is low then so is the air quality.

Some tips to keep the indoor ACH value high are:

✓ Open windows to increase ventilation and reduce the occurrence of moisture and odours from cooking and bathing.

✓ Ventilate stagnant areas within the home to reduce the build-up of pollutants in a specific area and their subsequent dispersal around the home.

✓ Use a dehumidifier in summer and a humidifier in winter (this may vary depending on what is normal for your ambient humidity). The object is to keep the relative humidity within the optimum range.

✓Use filters on your central heating furnace. These have a sticky coating that will trap dust, lint and clothing fibres and prevent them from dispersing throughout the house.


This substance is a naturally occurring radioactive gas found in the ground in areas of igneous rock and is a by-product of the decay of uranium. It is present in all building stone and seeps into houses through cracks. In the past there were enough draughts and cracks in houses to prevent the build-up of harmful concentrations of radon. With the improvements of building practices and building materials, homes have become better insulated and resistant to draughts so that the radon that normally escaped harmlessly into the environment now becomes trapped in unventilated pockets within the home.

Radon causes the most cases of lung cancer among people who do not smoke and overall is the second commonest cause of lung cancer.
If you live in a high radon area (and you should already know this or if you don’t look on your government’s website where information about radon and radon areas is freely available) then you should think about having your home checked for high concentrations of the gas. Many professional companies will carry out the monitoring and if it found that you have high radon concentrations can easily install radon vents which collect and divert the gas to outside.

Second-hand smoke

We all know about the problems caused by smoking tobacco but there is almost as much risk in being the victim of inhalation of second-hand smoke, i.e inhaling the smoke that others have already exhaled. Second-hand smoke is also called environmental tobacco smoke, involuntary or passive smoking.

Inhaling second-hand smoke can cause lung cancer and other smoking related respiratory diseases as well as heart disease and stroke. The Environmental Protection Agency (EPA) has published estimates of the results of inhaling second –hand smoke and reckons that approximately 3000 non-smokers die of lung cancer each year. It is especially harmful to children who often have no say in the matter as to whether they inhale other people’s smoke. It can worsen the symptoms of asthma, increases the risk of ear infections and SIDS (Sudden Infant Death Syndrome).

Combustion pollutants

If you have one of the following in your home then you probably have some kind of combustion pollutant as well:

  • Space heater
  • Gas stove
  • Wood stove
  • Fireplace
  • Gas water heater
  • Dryer

The types and concentrations of pollutants present in your home will depend on the type and age of the appliance, how well it has been installed, how well it is maintained, whether it is vented to the outside and what kind of fuel it uses.

Normally carbon monoxide is formed by the following processes:

  • gas or kerosene heaters without proper vents to outside
  • Poorly maintained flues, chimneys and furnaces
  • Backdraughts into the house from water heaters, furnaces, and multifuel and wood stoves and fireplaces. These are often caused by negative pressure in the home being the result of badly designed attic fans and air conditioning circuits among others
  • Natural and bottled gas stoves
  • Gasoline fuelled generators
  • Internal combustion engine exhaust fumes as a result of cars running stationary in enclosed spaces such as garages and workshops
  • Tobacco smoke
  • Gasoline and diesel driven vehicles from attached garages, parking areas and nearby roads
  • Incomplete combustion in poorly maintained gas stoves, unvented heaters and others
  • Improperly sized flues or blocked and disconnected ones
  • Leaking flues

The most common combustion pollutants include carbon monoxide and nitrogen dioxide:

Carbon monoxide. This is a colourless, tasteless, toxic and odourless gas that prevents oxygen from being delivered around the body. It is caused by the incomplete combustion of organic fuels. Because you cannot see or smell it the toxic fumes can build up rapidly within the home until they reach dangerous concentrations. The effects of exposure to carbon monoxide (CO) can vary depending on the individual, their age and their overall health, the concentration and length of prolonged exposure.

Average levels of carbon monoxide in the home without any fossil fuel burning appliances is between 0.5 and 5 parts ppm. Gas levels in homes that have well maintained and adjusted fossil fuel appliances range up to  15 ppm. Levels in homes that have poorly maintained and adjusted fossil fuel appliances may start at 30 ppm and rise rapidly.

✓ The ways to reduce the concentration of carbon monoxide in the home are:

✓ Keep combusting appliances well maintained and properly adjusted.

✓ If you are getting a nee unvented heater, consider buying a vented one.

✓ Use the correct fuel for the specific appliances. Use the fuel as recommended by the manufacturer.

✓ If you have a gas stove, get a vented exhaust fan.

✓ When buying wood stoves ensure they are properly sized and the emissions meet EPA standards.

✓ Have an annual inspection by a trained and licenced professional of all fossil fuel appliances, chimneys and flues. Have the professional clean, tune up and maintain the appliances and get rid of any possible leak as soon as it occurs.

✓ Prevent cars idling in the garage or outside open doors and windows.

There are some very low-cost carbon monoxide detectors available to buy that are worthwhile putting in all rooms with a combustion appliance or fireplace. Always follow the manufacturer’s instructions for siting the detector and make sure the fitted batteries are working properly.

Nitrogen dioxide. This substance is also a colorless and odorless gas but it causes irritation of the mucus membranes in the eyes, nose and throat, problems with breathing and shortness of breath, additional risks associated with respiratory infections.

Nitrogen dioxide in the home is predominantly caused by combustion such as:

  • Unvented fossil fuel combustion appliances such as gas stoves
  • Poorly maintained and installed vented appliances
  • Welding operations
  • Tobacco smoke
  • Kerosene heaters and lamps

As stated earlier nitrogen dioxide (NO2) irritates the mucus membranes of the eyes, nose, throat and lungs. In addition high dose exposure can lead to pulmonary oedema and permanent lung injury. If the exposure is continued it can lead to acute and chronic bronchitis. Low level exposure can affect persons already at risk such as asthmatics, those with chronic obstructive pulmonary disease and young children.

The steps needed to reduce exposure to this gas are the same as those for carbon monoxide, basically keeping all appliances well maintained and venting to outside.

Volatile organic compounds. These gases, also known as VOCs, are emitted by many ordinary everyday products used or even stored within the home. These include:

  • Household paints and varnishes
  • Wood preservatives
  • Paint strippers
  • Cleaning supplies and disinfectants
  • Insecticides
  • Pesticides
  • Office equipment such as some furniture, printers, copiers, correction fluid
  • Some craft materials such as glues and adhesives, photographic solutions and permanent markers
  • Building materials
  • Moth repellent
  • Air fresheners
  • Aerosol sprays
  • Dry cleaning solutions and dry cleaned clothing
  • Gasoline and kerosene

As with the other pollutants already mentioned, the severity of the adverse reaction will depend on the level of exposure, length of time exposed, general health of the person, the age and vulnerability of the person.

Some of the ways to reduce exposure to these VOCs are quite simple to implement and make sense if you think about them.

✓ Read the manufacturer’s instructions on the original container regarding storage, use and disposal and carry them out.

✓ Ventilate the area when using these products.

✓ Follow any instructions on the label or on the Safety Data Sheet (you can download this from the manufacturer’s website).

✓ Do not store opened containers within the house.

✓ One of the easiest VOCs to measure is formaldehyde. Identify the product and remove it from the house. If you cannot remove the panelling or surfaces which have been treated with the product then use an inert sealant.

✓ Rather than use pesticides use pest management techniques to reduce the need.

✓ Buy small quantities so there is less chance of storing opened containers.

✓ Dispose of unwanted product or empty containers in accordance with your local and national waste disposal regulations.

✓ Keep all products out of the reach of children and pets.

✓When using cleaning materials containing VOCs never mix them with other substances unless the label says it is safe to do so.

You must always follow the instructions on the label at all times. For example if the instructions say to use it in a well ventilated area, this means that preferably you should use it outside or in an area equipped with an exhaust fan. At the very least open all the windows to provide a through draught.

✓ VOC gases can leak from containers even if they are tightly closed so the best way to reduce the exposure is to keep the absolute minimum in the home. Instead keep them in a well ventilated area and away from contact with children.

✓ When you no longer need the products or the original container is empty you must not just throw them into the household garbage can. They must be regarded as toxic waste and disposed of according to the rules and regulations laid down in the environmental legislation in force in your country or state.

How do we prevent indoor air pollution?

The most obvious way to prevent your indoor air quality from becoming substandard is to prevent the pollutants from getting into your home in the first place.

Do you feel ill or have certain symptoms when you are at home and when you go out do the symptoms miraculously disappear?

Can you smell or see mildew or mold? Is there condensation on the windows or walls? Is the indoor air stuffy or stale? These all point to possible problems with ventilation which lead to poor indoor air quality.

Is your garage attached to the house? Do you store fuel for the lawnmower or car in there? How about paints, are they stored there too? All these can seep into the home and affect the air quality. Have you had work done on the house recently? Have you bought new carpets or furniture? Chemicals can be given off by these and disperse around the home too.

Ok. Hopefully, we have now identified that there is a problem with the air quality, what do we do about it?

Smoking. Do not smoke tobacco indoors. This is one of the main indoor pollutants. If you smoke then try not to smoke in the house or your car, smoke outside and ask your guests to do so as well.

Radon. If you live in a high radon area, then have your home checked for the presence of the gas. Depending on where you live you may now have to supply official radon concentration data when you decide to sell your house. Luckily it is easy to arrange for a test and also easy to remedy the problem.

Humidity. Keep the humidity in your home below 50%. If the humidity is any higher then you will encourage mold and mildew to grow. Using a dehumidifier or having air conditioning with help keep the water vapor to a manageable level. Make sure you clean the filters too. Fix any indoor water leaks too as these will also help molds to grow. Use exhaust fans to ventilate kitchens and bathrooms. Kitchen exhaust should vent to the outside air. Don’t use a gas stove without an outside vent.

Carbon monoxide. Buy a carbon monoxide detector (or better than one buy a few) and install them in accordance with the manufacturer’s instructions. At least put one in the room where you have the fireplace or gas stove or in fact any appliance that burns fuel. Put one in each of the bedrooms. Make sure you have a regular inspection of each of your fuel-burning appliances by an approved and licensed professional.

VOCs. Do not store gasoline, kerosene or heating oil indoors, either in the garage or in the basement. Throw away those almost empty paint cans and make sure the lids are firmly on the rest. If you must store fuels, paints and other chemicals then make sure it is in a sheltered place with lots of ventilation and not connected to the house. How about buying a small garden shed specifically for your chemicals? You mustn’t forget to keep it locked so the children don’t end up playing there when the weather is wet. Choose low VOC furniture and furnishings for your home. Don’t use pesticides or artificially perfumed air fresheners.

Dust and pet hair. Keep the place clean and use a vacuum cleaner with a HEPA filter to remove accumulated dust and hair. Reduce asthma triggers by not having too many soft furnishings like carpets or curtains. Place mattresses and pillows in airtight hypoallergenic covers to reduce exposure to dust mites. Wash bedding weekly to remove dead skin.

Houseplants to improve indoor air quality

In the late 1980s, NASA realized there was a problem with purifying the air in confined space craft facilities filled with VOCs. You obviously can’t just open a window for more ventilation on an orbiting space station, can you?

Working with the Associated Landscape Contractors of America they studied the effects that houseplants would have on air quality. The study found that there were several ordinary plants that were able to filter VOCs from the atmosphere.

Aloe vera. This succulent plant can help to reduce the levels of formaldehyde and benzene in your indoor air.

Spider plants (chlorophytum comosum). These resilient plants are great for potting indoors as they are very difficult to kill even if you neglect them. They have lots of foliage and tiny white flowers. In addition to their resilience, they help reduce levels of benzene, formaldehyde, carbon monoxide and xylene. As an afterthought, they are also safe to have in the house if you have pets.

Gerbera daisy (gerbera jamesonii). These are a bright flowering houseplant and are very good at getting rid of dry cleaning solvent trichloroethylene. Put one in the laundry room, your bedroom or if you have a walk-in closet and can provide lots of sunlight for it then it can do its job there too.

Snake plant (sansevieria triasciata ‘Laurentii’). This plant is also known as mother-in-law’s tongue and is probably the best plant for filtering out formaldehyde. Formaldehyde is very common in cleaning products, toilet paper, tissues as well as other personal care items.

One of these will do well in the bathroom as it loves the low light and humid air. These plants release oxygen at night so would be good to have one in your bedroom.

Golden pothos (Scindapsus aureus). This plant is another one that filters out formaldehyde. This will look lovely in a hanging basket because of its flowing cascade of greenery. Although they do best in bright indirect light with little water, they will stay green even if kept in the dark so one in your garage might help with the car exhaust. This plant is poisonous so don’t have it near small children and pets.

Chrysanthemum (chrysanthemum morifolium). As well as having bright colorful flowers, this plant helps to reduce levels of benzene commonly found in glue, plastics, paint, and detergent. Place it near an open window in direct sunlight as it loves bright light. Choose one that is suitable for indoor growing, not an outdoor variety.

Red-edged dracaena (dracaena marginata). This plant helps to remove xylene, trichloroethylene and formaldehyde, very common in gasoline, lacquers and varnishes. Although this plant grows slowly, be careful because it can reach up to 15 feet high.

Weeping fig (ficus benjamina). This plant will help filter out pollutants present in new carpets and furniture such as benzene, trichloroethylene and formaldehyde. This plant grows best in bright indirect light but can be difficult to get the watering conditions right.

Azalea (rhododendron simsii). This plant helps to filter out formaldehyde. Azaleas will grow best in cool areas of about 60°to 65°F (15°to 18°C). They prefer to have their leaves misted every few days.

English ivy (hedera helix). This plant will reduce airborne faecal matter as well as filtering formaldehyde. It likes moist soil and at least four hours of direct sunlight.

Warneck dracaena (dracaena deramensis ‘Warneckii’). This plant will filter out pollutants associated with oils and varnishes. It doesn’t need direct sunlight and can grow up to 12 feet high.

Bamboo palm (chamaedorea sefritzii). This plant, also known as the reed palm, likes shady indoor areas and can produce flowers and small berries. It is one of the best for filtering out trichloroethylene and benzene.

Heart leaf philodendron (Philodendron oxycardium). This plant is a climbing vine which is toxic if ingested so don’t use it if you have small children or inquisitive pets. It is however brilliant at removing all kinds of VOCs. It is a very low maintenance plant that loves places with low light.

Peace lily (spathiphyllum). This plant was the best, according to NASA, at removing formaldehyde, trichloroethylene, benzene, toluene and xylene. They like shade and only needs to be watered once a week.

How to DIY monitor your living spaces

If you need reliable results that will withstand scrutiny and that is admissible in real estate transactions then you must always have a licensed professional to test your air quality and produce a report. It can be expensive however if you just need to get an idea as to whether you have pollutants in your home and don’t need reliable results. Buying a kit and testing your home yourself is good as a screening tool to see if you need a more professional evaluation.

Radon testing kits. Of the many methods available, the ‘charcoal canister’ is the easiest for the DIY homeowner to buy. Using two charcoal packets for each test you will get results to screen your home for high levels of radon. This needs to be done annually. If the report is returned indicating high levels then it is recommended to have a professional conduct a continuous monitoring test with an alpha particle track testing device.

radion testing kit

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Mold testing. Mould is present in the air everywhere so if there was a commercial mold test it would always give a positive result. The problem with mold is if it finds favorable damp conditions on which to settle and grow. The best detectors for mold are the nose and eyes. Once you have decided that you have a problem then, by all means, try to tackle it yourself or call in a professional.

mold testing kit

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Carbon monoxide. In the case of carbon monoxide it is much better to have continual monitoring rather than testing. Carbon monoxide monitors are not very expensive and you should put one on every level of the house or in every room that has a fuel-burning appliance. If you have an attached garage then you should put a monitor in the room that shares a door with the garage.

Carbon monoxide monitor

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Lead paint. If you are considering renovating a building that was built before 1978 you must test for lead paint. DIY kits can be bought that involve taking a swab from suspected areas. The kits can be unreliable so if in any doubt always have a test done by a qualified professional. Identified lead paint can either be removed or encapsulated to render harmless.

lead paint test

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VOCs. Usually, just one test kit will identify most of the common VOCs. Use this test kit if you are having a physical reaction to something in the home but cannot identify it.

voc test kit

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Professional help for testing

In most countries, there are now legal requirements of vendors engaged in selling their houses to notify both the real estate agent and the prospective purchaser of any occurrence of indoor air quality pollutants and any work done to mitigate the presence and render them harmless.

Unfortunately, DIY home kits can be very unreliable and so are not acceptable as proof in home buying transactions. In this case, you will need the services of a qualified licensed professional who will conduct tests in accordance with national procedures and produce a reliable report.

Factors affecting costs

As always the cost to have the test done and a written report will vary depending on certain factors.

The size of your home. Not only will the professional be testing the air quality, he will also be trying to find the cause of the result. If your home is large then there will be more places to look for the culprit.

The number of pollutants. Sometimes you might want to test for just one pollutant whereas you may be after the results from many pollutants. Obviously, the specialist test for one factor will take less time and cost less.


The costs involved will vary depending on the type of testing required and the qualifications of the professional.

Figures shown in this section are indicative only and reflect an average value. Costs will vary depending on various factors.

Cost to test indoor air quality
Lower end$150
Higher end$900
Typical range$300 to $600
National average$400

The cost to buy DIY kits will vary depending on the supplier and where you propose to purchase the kit.

Costs to buy testing kits
Radon (Air Chek Inc.)$17 per packet. including analysis and report
Carbon monoxide monitor$20 to $40
Lead based paint swab kit$24 for pack of 8 swabs
Mould test kit$
VOC test kit$105 to $300


We all live in a sea of airborne particles and pollutants and our houses are full of them. Sometimes we can withstand their effects and sometimes we cannot. Whether we can or can’t there is no arguing that breathing in pollutants can be harmful to our health and our bodies in general. The obvious answer is to check if we have a problem, identify the source and remedy the problem. We hope this article has given you something to think about and helped you decide whether to have your indoor air tested for quality.

Thank you for reading.

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