Uncovering the harmful pollutants inside our buildings

When you think of air pollution, car exhaust pipes and factory smokestakes might come to mind. But there are certain pollutants that we are exposed to while indoors. Despite this, indoor air is essentially unregulated and unmonitored in Australia.

One group of pervasive indoor air pollutants is known as volatile organic compounds (VOCs). They are emitted by consumer products, such as air fresheners, cleaning supplies, and personal care products, and react with ozone to generate secondary pollutants such as formaldehyde. In industrialized cities, consumer products now constitute half of the VOC emissions from fossil fuel sources.

The aim of our work was to better understand the concentration and prevalence of VOCs within indoor environments in Australia. And from this, future work can now examine the effectiveness of strategies to reduce pollutants, to achieve healthier indoor environments.

Our work involved systematically evaluating 25 years (1991–2016) of peer reviewed scientific investigations into indoor concentrations of VOCs. We found that new homes had the highest VOC levels among all studies of domestic housing, and for nearly all pollutants, indoor levels were several times higher than outdoor levels. Among the most prevalent compounds indoors were terpenes, such as d-limonene and a-pinene.

Next, motivated by one of the gaps in the literature, we conducted our own indoor air quality investigation, by evaluating the concentration and prevalence of VOCs at a large Australian university.

We analysed 41 VOCs across 20 locations and found that indoor concentrations were higher than outdoor concentrations for 97% of all VOC measurements. We also found that certain types of VOCs were concentrated in particular buildings eg. The highest indoor to outdoor concentration ratios of formaldehyde (27), toluene (9), p-xylene (12), and m-xylene (11) were in a green building; highest of benzene (6) in renovated offices; and highest of o-xylene (9) in meeting areas.

This highlights that building materials and fragranced consumer products continue to be important sources of indoor VOCs, even in buildings with green certifications. Overall we have found that university indoor environments may be important sources of pollutants. Our assessment of the literature revealed that to enable comparisons among studies and with exposure guidelines, a standard approach for sampling and reporting VOC data is needed. Greater attention should be focused on indoor environments that are underreported and with vulnerable populations. Finally, what is also needed, and what has not yet been conducted, is a nationally representative study of indoor VOCs in Australia.

Building on the results from our university VOC study, future work can examine the effectiveness of strategies to reduce pollutants, such as through fragrance-free policies, selection of low-emitting construction materials and furnishings, evaluation of the green building certification scheme, and ongoing monitoring and assessment of indoor environments.

Our research has been presented by Professor Peter Rayner, and Dr. Cathy Oke at the CAUL Roadshow events in Canberra, Melbourne, and Sydney. Professor Anne Steinemann presented our research at a University of Melbourne public lecture titled “Hidden Hazards: Common Consumer Products and Indoor Environments.” Our research has generated enthusiastic discussion and keen interest from attendees. Nigel Goodman presented our research at an international conference in Philadelphia PA, USA (Indoor Air, July 22-27, 2018).

Image: Fragranced consumer products like these can contribute negatively to indoor air quality. Credit: Your Best Digs via Flickr (CC BY 2.0)

Excerpt from the CAUL Hub 2018 Annual Progress Report.