The heightened awareness of the importance of good indoor air quality is translating into new buying behaviours and consumer demands with respect to a building a modern home. The so called ‘indoor generation’ who are part of the ever-growing health and wellness movement are not content with the mediocre standards of the past. Consumers are becoming more educated about the health impact of their indoor environment and it is time that building professionals meet this demand by shifting the way homes are designed and built.
Building a healthy home may seem complicated or even overwhelming but by breaking down the various aspects of a build, the task can be simplified. Firstly consider the material the building is made from, then how the home is decorated or finished, which also includes the ventilation, and finally what we bring into the building and how we maintain the building. For the purposes of this article, I am going to focus on four common mistakes made when building or remodelling.
Overlooking the Importance of Insulation
Insulation is essential to achieve thermal health, one of the 9 Foundations of a healthy home. The term ‘thermal health’ is preferable to the narrower term ‘thermal comfort’ as it includes all of those impacts of thermal conditions on health that extend beyond just ‘comfort’. This is important because temperature and humidity can have a drastic effect on health, with heat waves and cold snaps known to cause significant mortality.
The checklist from the ForHealth team at Harvard states that a healthy building should ‘meet minimum thermal comfort standards for temperature and humidity and keep thermal conditions consistent throughout the day.’ Maintaining this can have a wide range of benefits for the occupants.
Many studies have shown that when thermal comfort parameters fall outside of the acceptable ranges there is a significant impact on human performance in homes, office and, schools. One such study on workplace thermal conditions and health impacts observed that workers experienced itchy, watery eyes, headaches, and throat irritation when thermal factors such as ventilation, humidity, and heat were unfavorable. When indoor environments are too warm, there is evidence of increase in sick building syndrome symptoms, negative moods, respiratory symptoms and feelings of fatigue.
Furthermore, temperature and humidity may impact disease transmission: cold and dry environments have been found to facilitate the spread of the influenza virus because low humidity levels allow virus particles survive longer but also because low humidity lowers our immune system. Studies exposing mice to influenza virus have shown have shown that at low humidity, nasal cilia (the microscopic hairs in our nose) become less effective at removing viral particles and mucous. Airway cells are less able to able to repair damage caused by viruses and, finally, interferons – signalling proteins that tell neighbouring cells that there is trouble ahead- are impacted.
This knowledge is hugely relevant in this era of the SARS-CoV-2 virus and it appears that, like influenza virus, low humidity is associated with increased infection. There may be many reasons behind this and research is still ongoing. What is for sure is that when humidity is lower, the air is drier and the infected aerosols are smaller. When we sneeze or cough, those smaller aerosols can stay suspended in the air for longer and this increases exposure to the disease. When the humidity is higher, the larger aerosols will fall more rapidly onto surfaces, thus removing them from the air where we would be likely to breathe them in. Researchers working on a study in Sydney discovered a 1% decrease in humidity was associated with a 6% increase in Covid-19 cases.
Choosing the insulation that contributes to optimal thermal health means that it must effectively contribute to maintaining thermal consistency (does the job it is intended to do) but also have minimal harmful impact. There are many chemicals that may be present in insulation, but should be avoided due to their harmful impact on health and their ability to trigger asthma and allergy symptoms.
To avoid mistakes when choosing insulation for a healthier home, be aware that:
- Spray polyurethane foam has been shown to induce asthma.
- Formaldehyde, required for chemical foaming action in urea formaldehyde foam, is a VOC that can irritate the airways and the skin. It may cause exacerbation of asthma and cause allergic contact dermatitis.
- Due to the flammability of polystyrene, insulation made from this material may contain fire retardants. These fire retardants, such as HBCDD, can cause risk to health through inhalation, and are listed by the European Union as a ‘substance of very high concern’.
- Isocyanate, which is needed for the foaming action in polyurethane foam and urea formaldehyde foam, may cause contact dermatitis, lung damage and asthma.
Insulation can also release dust and fibers into the air when it is being installed. Airborne fibers and dust can irritate the eyes, nose, throat and lungs. This can affect anyone, although the effects are likely to be more serious in those with asthma or allergies.
A new build provides a unique opportunity to ensure the home is as healthy as possible from the inside out. But if the project is a renovation or redesign of an existing room, it may be tempting to make the mistake of leaving the current insulation in place. Before making that decision it is worth considering that as insulation ages, it can become a threat to indoor air quality.
Over time, old insulation may introduce more and more dust particles and volatile organic compounds into the air. Insulation may also be providing a home for pests such as rodents and cockroaches. A cockroach allergy is a common trigger of year-round allergy and asthma. Studies show children who are allergic to cockroaches, and are exposed to them, need to go to the hospital for asthma more often than other children with asthma.
Insulation that has become wet over time is not only rendered useless but may also become moldy. Mold can cause sneezing, wheeze, cough and itchy skin even in those with no respiratory issues. In those impacted by asthma, it can be a serious trigger, so when choosing an insulation it is important to find one that is mold and mildew resistant.
It is also worth remembering that insulation can also release dust and fibers into the air when it is being installed. Airborne fibers and dust can irritate the eyes, nose, throat and lungs. This can affect anyone, although the effects are likely to be more serious in those with asthma or allergies. Installers should of course wear appropriate PPE and homeowners should move out during installation.
Fiberglass insulation is a material which can be made without some of the potentially sensitising chemicals that are present in some types of insulation, such as halogenated flame retardants. It is a reasonable, cost-effective option for consumers wishing to find healthier options for their homes. Familiarity with your client’s asthma or allergy triggers and any other health conditions or sensitisations will help guide you in selecting an appropriate insulation product and third party certification can also act is a helpful guide.
Ignoring Dust/Particles
Housewives of the past knew that keeping house contributed to health and wellness. They may not have been privy to the specific science behind the importance of ridding the home of dust but they had an awareness that dusting was good for the family. And they were right. Dust is far from an innocuous irritation. It acts as a sink or reservoir for numerous toxins, allergens and irritants that pose serious threats to our health. Failing to consider the removal of these particles is a serious misstep in planning a healthier home.
About one-third of household dust is created inside the home. The components differ depending on the construction and age of the building, the climate, the cleaning and the smoking habits of the occupants, so there’s no one recipe for house dust. Human skin cells are part of this debris, as are pet skin cells (dander) and dust mites. There are decomposed insects, some food debris (especially in the kitchen), fibers from carpets, bedding and clothes, and particulate matter from smoking and cooking.
Man-made chemicals make up the mix as well. For example, flame retardant chemicals that are used in consumer products migrate out of those products into air and dust. Flame retardants are Persistent Organic Pollutant (POPs), a name given to chemicals that are resistant to breakdown in the environment, and thus they can persist in dust for many years. Studies have documented that the amount of chemical that is present in indoor dust can be directly correlated with amount of chemical found in the blood of people living and working in those environments, providing evidence of the significant role dust can play in overall chemical exposure.
The other two-thirds of the indoor dust load actually comes from outside. This dirt and dust is tracked in on shoes and clothes and on the feet and fur of pets. It blows in through open windows, doorways and vents and it contains bacteria, viruses, pollen, mold spores, soil particles and lead.
Pests and domestic animals introduce allergens to the indoor environment which can trigger an immune response in humans. These pests and animals are primarily dust mites, cockroaches, mice, rats, cats and dogs. Dust mites are microscopic pests that feed on shedded human and animal skin cells, typically burrowing in bedding, mattresses and furniture upholstery. It is their faeces and body parts that pose a harmful threat to health as allergen. Mites have been associated with asthma, allergic rhinitis (hay fever), and other allergic reactions. Cockroach allergen too is a known trigger for asthma and has been identified as a risk factor for hospitalization in children with asthma. Pests like mice and rats release allergens in their urine and when the urine dries, the dust becomes resuspended and inhaled, potentially causing an allergic reaction.
We humans are exposed to these components in dust in three different ways:
1) Inhalation of resuspended dust. Dust on a person’s clothes, furniture, upholstered materials, from vacuuming or folding laundry is continuously suspended and resuspended through normal activities like walking through the house and is subsequently inhaled.
3) Ingestion from hand-to-mouth. This occurs when dirt and dust accumulate on our hands and are transferred to food or are ingested directly through hand to mouth contact. It is estimated that adults ingest up to 100 mg of house dust per day and children up to 200 mg per day.
When constructing of a healthier home, to ignore the threat of particles/dust to our health and in particular to those impacted by asthma and allergies would be seriously remiss. A whole house filtration system integrated into the HVAC system of the home is a great way to purify the air throughout the home and negates the need for air purifiers in each room. Because HVAC systems work by forcing air through ducts it is possible that these systems themselves can be a source of particle spread if they don’t have an effective filtration system. Effective filtration to protect those impacted by asthma and allergies requires that the filter is capable of capturing particles of different sizes and that a high percentage of pollen, dust mite allergen and cat allergen is captured. The filter must have capacity to remove particles during accelerated loading and post-cleaning and should also comply with strict limits on ozone emission.
Choosing Inappropriate Flooring
Flooring covers a substantial proportion of the home and so any emissions from installed flooring can contribute significantly to the indoor air quality. Choice of flooring may seem overwhelming as there is a wide variety available. Knowledge of some of the chemicals that may be emitted from the flooring material will make the choice significantly easier.
These harmful chemicals may include VOCs, phthalates, biocides and fungicides and organo-tin compounds. VOCs are chemicals emitted as gases from liquid and solid materials. Some VOCs are known asthma triggers. They can also cause eye, nose and throat irritation, headaches, loss of coordination and nausea, damage to liver, kidney and to the central nervous system.
Phthalates are plasticisers that are used to make rigid plastic more pliable and flexible and are potential carcinogens. They are also linked to asthma, birth defects, learning disabilities, reproductive problems and liver toxicity.
Biocides and fungicides may be added to flooring to prevent the growth of bacteria and fungi. These may include silver, ammonium bromide and mercaptobenzothiazole. Biocidal chemicals used in flooring can be sensitizing and can also cause contact dermatitis and respiratory irritation.
Because PVC may degrade or discolour at higher temperatures organo-tin compounds may be used as heat stabilisers. Organo-tins however have been shown to be toxic to the immune system and to the reproductive system.
All of these chemicals can pose a potential risk in the home and the choice of flooring type can have a major impact depending on an individual’s sensitivity to certain compounds and materials.
A second, but very significant, consideration is the adhesive used when installing the floor. Adhesives used to secure the flooring can emit harmful chemicals that can impact on those with sensitive airways. Click fit or nail-down installation should be considered instead of adhesive. If an adhesive must be used, select a low-VOC type. Third party certification is a good guide when choosing low emission flooring and adhesive.
Finally consideration must be given to the interaction of the flooring with potential allergens and how the flooring should be cleaned. Sticky allergen particles can be more difficult to remove from some types of flooring and if a floor necessitates the frequent use of strong chemical-laden cleaning products which themselves can release harmful chemicals, then it may be a poor choice in the long run.
Linoleum or laminate wood flooring are easy to clean and so have been recommended for a long time for those suffering from asthma and allergies. However, laminate or linoleum type flooring do not retain dust and allergens- unlike carpet which may trap/retain dust and allergens- and regular mopping and cleaning is required to prevent aerosolization of dust and particles as people walk on the flooring. The joins between pieces of flooring can be different shapes – square, bevelled, etc. – and this can determine how easy or hard it may be to remove allergens. Easy to clean surfaces, so that irritants and allergens can be kept to a minimum without too much effort, is crucial.
Natural material such as solid wood floors, tiles or recycled wood can also all make good choices that are less chemically treated. However, natural flooring materials can be very expensive. This must be balanced against the fact that cheaper products are more likely to be manufactured with potentially harmful chemical ingredients.
The choice of flooring should be driven by knowledge of the sensitivities of the occupant. It is essential to consider which type is most appropriate for the individual client and has less impact on asthma and allergies. Third party certification is a good guide when choosing low emission flooring and adhesive. Certification of flooring for those impacted by asthma and allergies should depend on the substantial reduction of allergen on the floor after cleaning and minimal increase in allergen levels in the air during cleaning. Furthermore, any certified flooring should emit minimal VOCs- both from the adhesive and from the flooring itself.
Choosing Conventional Paint
Conventional paint can contain many chemicals that may be harmful to health in general and, in particular are considered a problem to those impacted by asthma and allergies.
Volatile organic compounds (VOCs) are probably the most cause for concern but other chemicals such asmercury, propylene glycol and glycol ethers may also be present. VOCs are chemicals emitted as gases from liquid and solid materials, and in particular are associated with oil based paints. Some VOCs are known asthma triggers. They can also cause eye, nose, and throat irritation, headaches and nausea.
Exposure to high concentrations of VOCs for extended periods can cause long-term damage to certain systems of the body, including to the nervous system, liver and kidneys. According to the U.S. Environmental Protection Agency, some VOCs are suspected carcinogens. Children are especially susceptible to harmful effects: A study published in 2010 investigated VOC levels in children’s bedrooms and found that higher levels of propylene glycol and glycol ethers led to a greater likelihood of conditions, such as asthma, eczema and rhinitis. Another study has shown that paint fumes can be especially dangerous for newborn babies, causing an increased the risk of childhood leukaemia.
A fresh coat of paint will continue to emit VOCs into the air even after it appears completely dry so it is wise to ventilate a room for 72 hours after painting, even if the smell of paint fumes has already dissipated, as some of the most toxic VOCs can be odorless.
Though the majority of VOC off-gassing typically happens during the first week after painting, surfaces can continue to emit harmful chemicals for years to come. In the air, these chemicals can cause chemical reactions with other pollutants such as fine particulates and ozone, both of which have been found to have negative health impacts.
Paint products should be selected carefully, taking due consideration of any chemical sensitivities the home occupants may have. Water-based paints have significantly lower solvent and VOC content and are generally a healthier choice. Use of a water-based paint also removes the need for strong cleaning chemicals for paintbrushes and therefore removes an additional source of VOCs.
In the past decade significant steps have been taken to reduce and remove the amount of harmful chemicals used in paint so that now there is a much wider choice of paint available.
This has been in response both to consumer pressure and tighter regulations around the VOC content of paints. Significant advances have occurred in the paint sector, including better formulation technologies and new additive options that has led to the development of healthier paints that can perform on par with traditional solvent based products. This has been necessary as consumers are unlikely to purchase a healthier product if it is less effective than the alternatives.
This progress has, and continues to be, a challenge as some constituents of paints are necessary for paint to perform properly yet are known allergens or irritants. Biocides are one such example- these are essential to prevent mold growth in the paint, but are potentially harmful to those with sensitive airways. Third party certification indicating a paint is healthier should ensure that constituents such as biocides are present at the lowest level at which they are effective and so is a helpful and trustworthy guide to choosing the right product for your build.
In general, with these advances, labelling on paint tins has become more transparent and informative making it easier to select appropriate products. Considering all these developments, to choose a conventional paint is certainly considered a mistake when building a healthy home.
Conclusion
Building a healthier home does not need to be complicated or difficult but it does help to have an understanding of the health impact of poor indoor air quality and some knowledge of the potential toxicants, irritants and allergens that may be emitted from various materials and products in the home. Taking time to learn about the health impact of living with poor indoor air and the consequences this may have on those living with asthma and allergies and other respiratory illnesses will provide insight and understanding that will simplify and facilitate the building of a healthier home. The modern consumer has an expectation that their building professional is educated about healthy indoor environment, it is no longer considered an optional extra. It is now necessary to go beyond code to meet this demand and deliver a better, healthier build.
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Medical & Lifestyle Author Dr Anna O’Donovan
About Dr. Anna O’Donovan – Medical & Lifestyle Author
Anna is a mum of three children, one with allergies, and she suffers from allergies and asthma herself. She is a qualified doctor and worked as a General Practitioner and as a dentist for a number of years. She is also an award-winning author.
Key Words
indoor air quality, insulation, environment, construction industry, design, air quality, asthma, healthy, allergies, allergens, air purifiers, healthy home, air cleaner, building materials, flooring, adhesives, paint, VOCs, chemicals, cleaning products, irritants, pollutants
References and further reading
EEBA, the leading resource for information and education for sustainable building Click here
Construction Instruction, helping you build better, longer lasting, healthier homes Click here
Harvard T.H.Chan School of Public Health 9 Foundations Click here
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