SoE 2006 > Atmosphere > 3.5 Indoor air quality

3.5 Indoor air quality

The long-term health impacts of the large number of chemicals found in indoor air are poorly understood.

Indoor air quality is an important issue for human health. It is estimated that people spend between 75% and 95% of their time indoors where the quality of the air can be poorer than outdoors.

Ongoing research continues to highlight the impacts on indoor air quality, especially the out-gassing or release of formaldehyde from building materials, fixtures and fittings, and also the operation of unflued gas heaters in areas with poor ventilation.

The implementation of the Smoke-free Environment Amendment Act 2004 in hotels and licensed clubs, and the rise in smoke-free homes means that there is a large increase in indoor areas which are now free of tobacco smoke.

NSW indicator

Introduction

Indoor air includes air in homes, schools, shopping centres, vehicles, and indoor workplaces. Australians spend approximately 85% of their time indoors, much of it at home (EPHC 2004). The quality of indoor air depends on factors such as the type of building materials used; the types of products used indoors (including paint, electrical appliances, furniture and cleaning products); the proximity to outdoor sources of air pollution; types of indoor heating or cooling used; building ventilation rates; the use of the building (including whether smoking occurs); and diurnal, seasonal and climatic conditions. Many pollutants, such as nitrogen dioxide, carbon monoxide, fine particles and formaldehyde, can be present at higher concentrations indoors than outdoors (Sheppeard et al. 2002; DEH 2004). The National Occupational Health and Safety Commission sets exposure standards for workplaces, but there are no Australian standards for indoor air in other settings.

The primary concern with indoor air pollution is the link between pollutants and human health. The long-term health impacts of the large number of chemicals found in indoor air are poorly understood. Some are suspected of contributing to long-term effects such as cancer and damage to the nervous, immune and reproductive systems. Some indoor air pollutants (nitrogen dioxide and fine particles) can cause breathing difficulties, especially for at-risk groups such as people with asthma or other lung problems, very young children and frail older people. Pollutants from tobacco smoke can lead to respiratory and heart disease, cancer and foetal harm. Other indoor pollutants, such as formaldehyde, are associated with readily observable immediate health effects such as irritation of the eyes, nose and throat or of the nervous system, often experienced as headaches.

A number of chemicals are directly emitted from cleaning chemicals or the surfaces of building materials and other products. For example, formaldehyde is emitted by processed wood products such as particleboard, and brominated flame retardants are emitted by computers and couches. Research suggests that exposure should be avoided or minimised by choosing safer products (with less hazardous ingredients or lower emissions).

Indoor air pollutants also include moulds, which can affect people with respiratory problems, and bacteria such as Legionella pneumophila (Legionella) which causes Legionnaires' disease and can be contracted by inhaling infected aerosols generated by engineered warm-water sources such as spa pools or tepid water system showers. Outdoor sources of contamination include cooling towers or soils containing Legionella.

Current status and trends

Monitoring in NSW homes has identified environmental tobacco smoke, solid-fuel heaters and unflued gas as important indoor sources contributing to poor indoor air quality as they raise concentrations of fine particles, carbon monoxide and nitrogen dioxide (Sheppeard et al. 2002; DEH 2004).

The NSW Health Survey is a continuous, computer-assisted telephone survey that looks at health-related behaviours and other risk factors across NSW. Data from the 2002 survey shows that unflued gas heaters remain the primary heater in around 20% of homes (NSW Health 2003b). Solid-fuel heating is used in around 15% of homes.

In 2003 pollutant monitoring undertaken in Sydney homes found that those using unflued gas heaters frequently had nitrogen dioxide concentrations exceeding the WHO 1-hour guideline of 110 ppb (guideline exceeded at least once on 67% of house-days tested) (DEH 2004). A small number of homes also exceeded health guidelines for carbon monoxide and formaldehyde, also emitted by unflued gas heaters.

The NSW Health Survey also reported that 84.3% of households in NSW were smoke-free in 2004, an increase of 14.5% since 1997 (NSW Health 2000; NSW Health 2005). Between 2001 and 2005, the Environmental Tobacco Smoke and Children community education project (see 'Response to the issue') found that the number of smoke-free homes had increased by 56% and the number of smoke-free family cars by 42%.

In the 10 years since 1997, notified cases of Legionnaires' disease in NSW have ranged between 33 and 88 per annum (NSW Health 2006).

Information on these forms of indoor air pollution has improved. However, there is little information available on many of the chemicals released to indoor air from solid-fuel heaters and out-gassing from household products, including those suspected of contributing to adverse health effects.

Response to the issue

Tobacco smoke

The Smoke-free Environment Amendment Act 2004 has extended the areas where smoking is no longer allowed. The Smoke-free Environment Act 2000 introduced smoking bans in restaurants and their bars; cafes and cafeterias; shopping centres, malls and plazas; community centres; and dining areas of hotels. Amendments that commenced in 2005 restrict smoking to only one room or area of a licensed venue, comprising less than 50% of the combined bar, gaming and other recreational areas. From 2007, smoking will not be permitted in any enclosed public place in NSW.

The Environmental Tobacco Smoke and Children community education project aimed to reduce infant and child exposure to environmental tobacco smoke in cars and homes in NSW. Managed by a joint task force with members from NSW Health, the Cancer Council NSW, the Heart Foundation (NSW Division), Sudden Infant Death Syndrome Association, and Asthma NSW, the project comprised mass media advertising, resources and training for health professionals, information and resources for parents, community grants, a website and ongoing evaluation.

Ventilation and building design

Minimum standards relating to ventilation are contained in the Building Code of Australia (BCA) (ABCB 2006) which has been given the status of a building regulation throughout Australia.

The role of the BCA in promoting better indoor air quality may increase in the future as the Australian Building Codes Board (ABCB) recommended in 2004 that sustainability, which is to encompass indoor environmental quality, should be a goal of the BCA and should be considered in future reviews (ABCB 2004). A new agreement among the Commonwealth, states and territories is expected to adopt this recommendation.

Home heating

NSW Health has produced a fact sheet about the potential risks from unflued gas heaters in homes, and distributed brochures through community health centres and Divisions of General Practice in NSW (NSW Health 2004d). The Australian Standards Committee is considering improved labelling of unflued gas heaters to make consumers more aware of the potential risks of exposure to emissions (Standards Australia 2005). NSW Government programs to reduce outdoor air pollution from solid-fuel heaters will also assist in reducing indoor fine-particulate emissions from these appliances (see Atmosphere 3.3).

Home renovation dusts

In 2005, NSW Health and DEC jointly developed the Do-It-Yourself Safe Program to increase awareness of the hazards and risks encountered by home renovators. Typical home renovations can create airborne hazards such as asbestos fibres from fibro, copper chrome arsenate from treated timber, lead from old paint, and VOCs from a variety of products such as lacquers and paints. Being aware of the hazards and risks involved will assist renovators to minimise or eliminate any impact.

Volatile emissions from surfaces, furnishings and consumer products

The Office of Chemical Safety is reviewing exposure to, and the health effects of, formaldehyde. This will lead to advice for minimising human exposure to this hazardous chemical (NICNAS 2005).

Legionnaires' disease

The Public Health (Microbial Control) Regulation 2000 was introduced in NSW to deal with air and water quality in relation to Legionnaires' and other diseases. It makes the water treatment industry more responsible and accountable for ensuring that water-cooling and warm-water systems are installed, commissioned, operated and maintained in such a way as to prevent the proliferation of the Legionella bacteria. Building occupiers can maintain their cooling towers either in accordance with requirements prescribed within the regulation, or by a performance-based approach (Standards Australia 2002). To assist the water treatment industry, a code of practice for the control of Legionnaires' disease has been reviewed and updated (NSW Health 2004e).

National Indoor Air Project

The Commonwealth Department of the Environment and Heritage (DEH) is currently conducting an Indoor Air Project, in consultation with health agencies. This project is designed to assess whether there are grounds for a national response to Australia's indoor air problems and, if so, to identify options for national actions. The intention is to release a public discussion paper in 2006 seeking input from the community on potential responses to identified problems with indoor air quality.

Building rating schemes

Introduced in 2003, Green Star is a voluntary environmental rating system administered by the Green Building Council of Australia. Green Star evaluates the performance of a building at the design stage in eight categories, one of which is Indoor Environmental Quality. The system assesses a number of factors – ventilation, lighting, occupant comfort and indoor pollutants – against performance-based, non-prescriptive targets. In addition to currently assessing Class 5 (Commercial Office) buildings, rating tools are being developed for other building types.

The National Australian Built Environment Ratings Scheme is a national initiative, managed by the NSW Department of Energy, Utilities and Sustainability. The scheme measures an existing building's overall environmental performance during operation. Energy, greenhouse efficiency and water components of the tool have been implemented to date; other components, including indoor air quality, will be developed during 2006 and 2007.

Future directions

There is growing awareness of indoor air quality, and researchers and governments are still developing their understanding of the pollutants and associated health risks found in indoor environments. Governments need to continue research and monitoring to better understand and quantify the extent of the problems so that effective responses can be developed where needed. Long-term health impacts of low levels of chemical mixtures may be particularly important.

There is also a need for greater understanding of the prevalence of mould and its associated health effects, and of effective mitigation strategies.

Regulatory action is reducing Legionella contamination and levels of tobacco smoke indoors, but policy responses to other indoor air quality problems are less developed. Emissions from unflued gas heating and from surfaces, furnishings and consumer products are in need of attention. Potential responses being examined by DEH's Indoor Air Project include the development of national guideline values for indoor air pollutants, emissions labelling for products such as particleboard and paint, and information resources for consumers.

There is growing interest in the potential for increasing the role of building codes and requirements for better ventilation and management of indoor air quality. There is also growing interest in the potential to control the construction and installation of domestic appliances and furnishings. The ABCB has recommended that future BCA building codes should include sustainability criteria towards these ends (ABCB 2004).