Also, while the intention may be to save energy and cost, that is not necessarily the result, say the researchers, from the Mackintosh Environmental Architecture Research Unit (MEARU) at The Glasgow School of Art, working with Strathclyde and Caledonian universities, because in order to dry off the 2 litres that the average load of washing releases into the air, people often turn up the heating.
The three-year research project, titled "Environmental Assessment of Domestic laundering", was funded by the Engineering and Physical Sciences Research Council (EPSRC). A report and press statement were released on 2 November.
Report co-author, Colin Porteous, a professor at MEARU, says:
"Because of increased awareness of the energy consumption of tumble dryers many people are choosing to dry clothes passively within their home."
"This results not only in a severe energy penalty, because of increased heating demand, but also a potential health risk due to higher moisture levels," he adds.
Researchers suggest a strong correlation between drying laundry indoors and increased spore growth, which can exacerbate symptoms for sufferers of asthma, hay fever and other allergies.
They concluded indoor drying of laundry poses environmental, economic and health problems, and the tendency in the UK toward building smaller, more airtight homes, only serves to make things worse.
In ill-ventilated rooms, putting clothes on radiators to dry can account for up to a third of the moisture in the air, and creates ideal conditions for mould spores to grow and dust mites to thrive. Both these conditions are known triggers of asthma.
The researchers also point out that indoor drying of clothes that contain fabric conditioner is likely to increase the amount of cancer-causing chemicals in the air.
Indoor laundry drying also leads to increased use of energy, as radiators are often turned up to help the drying process, and/or windows are opened. This just worsens fuel poverty, already a major issue in the West of Scotland, say the researchers.
The team recommends people dry their laundry outdoors whenever possible, or use energy-efficient, condensing tumble dryers. If you have to dry your clothes indoors, then place them by a south facing window (the message is for people in the UK), using natural light and heat. An even better method is to place the clothes on a south-facing balcony, if you have one.
They also suggest, when creating new housing stock, planners and builders should make sure the designs cater for ways of drying laundry that do not contribute to poor air quality. The researchers have published a design guide with suggestions like: upgrading balconies and sunspaces, ensuring new homes have a drying space with its own heating and ventilation, communal laundry and drying facilities, and installing energy-efficient appliances.
The team is now discussing its findings with social housing authorities, with a view to their proposals being adopted as Housing Associations upgrade existing stock and build new homes.
However they argue more sweeping changes are necessary, including updating the Building Regulations so they apply to all new housing. Such a move would have many benefits, says Porteous:
"Our research gives strong justification for the changes both in terms of health and wellbeing, and associated economic impacts. It is our hope that current statutory and advisory standards will be modified to take them on board ensuring a healthy and economically sustainable living environment."
Written by Catharine Paddock PhD