People with asthma and allergies are advised to avoid volatile organic compounds (VOCs)1,2, but in certain circumstances these can be unavoidable. When carrying out necessary tasks such as painting the home, how can you reduce your exposure and what should you be looking out for in your paint?
Organic solvents are the main source of VOCs in paint. A solvent is the carrier or vehicle for the paint. Organic solvents carry the paint to the wall and allow it to spread; it then evaporates leaving the paint on the wall in an even film. Unfortunately, this evaporation of organic solvents is the main source of VOC. This can cause “Eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidney, and central nervous system”3. These side effects are not restricted to those suffering from asthma, however throat and lung irritation can cause a substantially greater problem for those suffering from asthma as it can prompt an asthma attack2.
In the past decade significant steps have been taken to reduce the amount of organic solvents used in paint. However, often the lower-solvent compounds are the most effective. In the development of more desirable paints, significant steps have been taken to ensure that the quality of the paint also remains a priority. For a consumer product to be commercially successful it must appeal to the mainstream; consumers won’t purchase a ‘greener’ product if it is less effective than the alternatives4.
Water-based paints were created in response to demand for healthier and greener paint options. These paints use water as the carrier or vehicle. Advances in formulation mean that some water-based paints now perform on par with solvent based paints. Water-based paints have significantly lower solvent and VOC content, and are easier to clean up, also removing the need for toxic mineral spirits. With the removal of solvent from paint, certain functional properties need to be replaced with substitute compounds.
Microorganisms can’t grow in cans of solvent based paints, therefore water-based paints, require a preservative to suppress any significant microbial growth. In 2017, a well known paint company removed a preservative from a paint line that was on sale in an independent DIY chain. Unfortunately, as this was a water based paint, this removal allowed bacteria to grow in the paint cans. When the paint was applied to walls, it resulted in a smell that was compared to cat urine and rotten animals! This smell was due to the production of ammonia and hydrogen sulphide by bacteria in the paint cans5.
The company has since re-added the preservative to the paints, and did maintain that the paint only emitted these odours ‘in exceptional circumstances’, the DIY chain also compensated people affected by this problem (although not always to their satisfaction)5.
Chemicals and their function in paint
Paints are generally made up of several compounds that carry out specific functions listed below6:
|Pigments||To impart colour and opacity|
|Binder||A polymer (or resin) to hold the pigment in place|
|Extender||Larger pigment particles that are added to give additional functionality – strengthening the film, improving adhesion, etc|
Either an organic solvent or water can be used to reduce the viscosity of the paint and to make it easier to spread
|Additives||To modify the properties of the liquid paint or dry film, eg anti-fungal.|
There are a range of other chemicals that may be found in paints and may pose health concerns in general7. These include:
Formaldehyde is added to paint to inhibit bacterial and fungal growth. However there are several health concerns with respect to the off-gassing of formaldehyde from freshly painted indoor surfaces. An increase in formaldehyde and VOC levels after painting correlates with asthma and bronchial hyper-responsiveness8. A relation between nocturnal attacks of breathlessness and indoor concentrations of formaldehyde and VOC in the home was also found9. The United States Environmental Protection Agency (EPA) recognised that everyone is exposed to small amount of formaldehyde in the air, and exposure can cause irritation of the eyes, nose and throat and neurological effects10.
Acetaldehyde is added to paint as a binder. Although it is also present in the environment in low levels, and is even produced in the body after the breakdown of alcohol, exposure to acetaldehyde off-gassing can cause irritation of the eyes, skin and respiratory tract11. Acetaldehyde is also a specific inducer of airway hyper-responsiveness in asthmatic patients12.
Phenylmercuric acetate is used as a preservative to prolong the shelf life of paint by inhibiting the growth of bacteria and fungus in water-based paints. In one particular published case, a child exposed to paint fumes in his home for 10 days was hospitalized with acrodynia, a form of mercury poisoning. A follow up study investigated homes painted with the same brand of paint and found increased mercury concentrations in the urine of inhabitants. The particular brand of paint contained 2 ½ times the EPA recommended limit for mercury13. Phenylmercuric acetate has been banned for use in paint in several markets including the European Union and the USA.
Water based paints can contribute to a lower overall VOC exposure, however a study in 2010 showed a correlation between PGEs (propylene glycol and glycol ethers) and greater risk of developing asthma and allergic diseases. PGE is a VOC that has a lower volatility than other VOCs, and still performs very well as a solvent. For this reason it can be used in water based paints in order to reduce the overall VOC levels, but nevertheless has its own exposure concerns14.
What are ‘Healthier’ Paints?
Significant innovation has occurred in the paint sector in the last decade, including better formulation technologies and new additive options. These have facilitated the development of more sustainable paints that can perform on par with traditional solvent based products15.
The production of more sustainable, ‘healthier’ paints has been in response both to consumer pressure, and tighter regulations around the VOC content of paints. Following application, paints can continue to emit VOCs as they dry. Standardised testing for the determination of the VOC profile of paint, measures emission at specified time points eg 24, 48 and 96 hours16. While most people would ventilate a room well while they are painting, ventilation may be required for a period of time after the paint has actually been applied.
How to identify low VOC paints?
Several programs exist that test paint and provide a certification mark, based on the paints’ compliance with their testing standard. As well as determining relative safety, these certification marks may also measure performance of the paint.
The Green Seal Certification for paints assesses these products on the basis of environmental impact. It includes testing for performance, health and environmental requirements, end-of-life management, packaging and labelling requirements. In terms of health aspects, there are a range of chemicals that are banned, and limits are defined of VOCs in the paint product, as well as once applied and emitted17.
UL Environment – Greenguard
Greenguard certification is primarily focussed on promoting healthier indoor environments and was first established to assist EPA purchasing decisions. The Greenguard certification for paint, tests for total VOC levels in the paint, as well as emissions over time. This standard is primarily focussed on air quality and does not measure performance characteristics18.
Scientific Certification Systems (SCS)
The SCS Indoor Advantage Gold is also focused on indoor air quality. Compliance with this certification standard is measured based on indoor air quality modelling and VOC emission over time. Similarly to the UL Environment standard, the SCS Certification does not address performance characteristics of the paint19.
asthma & allergy friendly®
The asthma & allergy friendly® Certification Program is operated by Allergy Standards Ltd in collaboration with the Asthma and Allergy Foundation of America, Asthma Canada and is also operated internationally through a global certification mark. Paint certification is based on the impact on the indoor environment for those suffering from asthma and allergies. The programme assesses the chemical constituents of the paint for toxins and allergens, as well as testing VOC emissions over an extended time course. Finally the physical performance characteristics are measured to ensure the quality of the product20.
What should you do next?
While avoidance of triggers is a key part of an asthma management plan, this may not always be an option. In these circumstances, steps should be taken to minimise exposure as much as possible.
- Minimise sources of VOCs – select a paint that has been designed (and tested!) to be low in VOCs. Select a paint that has been certified by a third party agency if possible, and educate yourself as to what that certification means
- Use of water based paint to remove the need for white spirits and therefore to remove an additional source of VOCs
- If you are particularly sensitive to the chemicals contained in paint, use appropriate protective clothing – gloves, goggles, face mask
- Paint well in advance of use of the room if possible, to allow time for VOCs to complete their emission timeline
- Always paint in a well ventilated area. Paints can emit VOCs for many hours following application (up to 14 days!) and so even after painting the area should be kept as well ventilated as possible.
You should always follow your healthcare professional’s advice. If the purchase and use of paint is absolutely necessary, try to minimise exposure and select the most inert paint possible based on defined, tested measures.
About the author
Thanks to Dr. Tim Yeomans for this insightful article.
Dr. Tim Yeomans is the Centre Manager for Shannon Applied Biotechnology Centre, a collaboration between two third level colleges in Ireland. Tim holds a PhD in Microbiology and postgraduate qualifications in Technology Commercialisation and Innovation Management. Tim has worked in research and development for 20 years, both in industry and academia. In his role in Shannon ABC, Tim is responsible for the scientific direction of the Centre, intellectual property management and business and technology development.
chemicals, paint, VOC, healthier, allergen, asthma, allergy, certification, asthma & allergy friendly
- National Asthma Council Australia [online]. Accessed June 2018
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- Norback, D., Bjornsson, E., Janson, C., Widstrom, J., & Boman, G. (1995). Asthmatic Symptoms and Volatile Organic-Compounds, Formaldehyde, and Carbon-Dioxide in Dwellings. Occupational and Environmental Medicine, 52(6), 388–395
- Agency for Toxic Substances and Disease Registry (ATSDR). 1999. Toxicological Profile for Formaldehyde. Addendum to the Profile for Formaldehyde. 2010. Atlanta, GA: U.S. Department of Public Health and Human Services, Public Health Service
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- Sánchez-Toril, F & Prieto, L & Peris, R & Perez, JA & Millan, Monica & Marín, J. (2000). Differences in airway responsiveness to acetaldehyde and methacholine in asthma and chronic bronchitis. The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology. 15. 260-5. 10.1034/j.1399-3003.2000.15b07.x. .
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- Choi, H, Schmidbauer, Sundell, J, Hasselgren, M, Spengler, J and Bornehag, CG. Common Household Chemicals and the Allergy Risks in Pre-School Age Children. 2010 PLoS ONE 5(10): e13423. doi:10.1371/journal.pone.0013423
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