State of the Environment

2001

Human Settlements Theme Report

Australia State of the Environment Report 2001 (Theme Report)
Lead Author: Professor Peter W. Newton, CSIRO Building, Construction and Engineering, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06747 7

Emerging issues (continued)

Population health and well-being

As indicators in this report suggest, recent health trends for Australians have been generally positive, although Indigenous communities have largely missed out on the improvements. For Australians in the 21st century, health-related risk factors can be assigned to several major categories (after Guest et al. 1999):

Emergence of new diseases

As the battle to control known diseases continues, other new threats have emerged. Diseases once thought to be retreating have re-emerged. Worse still, new diseases have emerged-many of them unpreventable or untreatable at present. Some have affected international trade and tourism, while others have led to the mass slaughter of poultry and farm animals, as in the case of outbreaks of foot-and-mouth disease in the UK in February 2001. Many have overwhelmed health services and caused significant illness and death (WHO 1999).

Several different factors contribute to the emergence or re-emergence of diseases, including social, economic, political and ecological factors, and the interactions of organisms, hosts and the environment (Longbottom 1997). The changing distribution of populations, the increase in international travel, the development of resistance to antimicrobials, changes in human behaviour and changes in the environment have all contributed to disease emergence.

Australia is not immune to the emergence of new diseases. Recently recognised diseases/organisms in Australia include bat paramyxovirus which causes respiratory disease in humans and horses (Selvey and Sheridan 1994), and a lyssavirus which causes neurological symptoms in humans (Allworth et al. 1996). The first reported outbreak of Japanese encephalitis in Australia occurred in the Torres Strait in 1995, with the first case reported on the Australian mainland in 1998 (AIHW 2000a). There has also been a resurgence of some vaccine-preventable diseases, with widespread outbreaks of measles, pertussis and rubella (Longbottom 1997).

Environmental changes and health

Scientific evidence suggests that the trends in global warming and changing patterns of extreme weather conditions seen in the past few decades may signal unprecedented rapid climate change. Predicted impacts within the next 50 to 100 years include regional decreases in agricultural production, increased prevalence of diseases spread by mosquitoes and other insects, water shortages, and the displacement of tens of millions of people in developing countries through rising sea levels.

Considerable attention has been drawn over the past few years to the possible effects of global warming on human health. This enhanced greenhouse effect, combined with increased ultraviolet radiation as a result of stratospheric ozone depletion, may already be affecting human health in many parts of the world (WHO 1996). Particularly important are the spread of vector-borne diseases and exposure to ultraviolet radiation.

Exposure to ultraviolet radiation

Ozone in the atmosphere absorbs much of the dangerous ultraviolet (UV) radiation before it reaches the ground, but we can still receive enough to cause sunburn and more serious health problems (ARPANSA 1999a). Depletion of the stratospheric ozone layer results in people and the environment being exposed to higher intensities of UV, particularly its more damaging component, UV-B. (See the Atmosphere Theme Report for more details.)

Parts of the body most affected by UV exposure are the skin, eyes and immune system. Exposure to sunlight is known to be associated with various skin cancers, accelerated skin ageing, cataracts and other eye diseases, and possibly has an adverse effect on a person's ability to resist infectious diseases (UNEP 1998, WHO 1998a, ARPANSA 1999b).

Short-term or acute effects of UV exposure include sunburn and photosensitivity. The skin is the principal human barrier to the outside environment, and thus the first line of defence against foreign objects that may threaten health (Longstreth et al. 1998). Long-term or chronic effects of UV exposure include skin dryness, blemishes, ageing, freckles, moles, solar keratosis (pre-cancerous growth of skin cells) and skin cancer, including non-melanocytic skin cancer and melanoma (Longstreth et al. 1998, WHO 1998a, ARPANSA 1999c).

Exposure to UV radiation is also known to impair vision by damaging the cornea, ocular lens and retina (Ewan et al. 1991, ARPANSA 1999c). Effects of UV on the eye include photokeratitis, pterygium, retinal damage such as age-related macular degeneration, cancer of the eye and cataracts.

There is some evidence to suggest that UV exposure of the skin at hazardous levels suppresses some immune response mechanisms in humans.

Vector-borne diseases

Climatic changes are also expected to increase the activity of arboviruses and other viruses by extending the habitats of their mosquito vectors. They may also create a suitable environment for malaria transmission. Globally, a mean temperature increase of 1-2geographical areas, leading to increases in cases of vector-borne diseases, especially in populations living just outside the areas where these diseases currently occur (WHO 1998b). Changes in precipitation and temperature could radically alter the patterns of vector-borne and viral diseases by shifting them to higher latitudes and higher altitudes, thus putting larger populations at risk (McMichael 1991, Patz et al. 1996, WHO 1996).

It is widely recognised that weather is important in the genesis of outbreaks of human arboviral disease in Australia. The main mosquito-borne diseases of concern in Australia are encephalitis (caused by Murray Valley encephalitis and Kunjin viruses), epidemic polyarthritis (caused by Barmah Forest and Ross River viruses), dengue fever and malaria. Heavy rainfall and flooding may result in outbreaks of Murray Valley encephalitis, while these and other environmental factors such as rising sea levels may lead to greater tidal penetration of coastlines and an increasing incidence of Ross River virus infections (Patz et al. 1996, Mackenzie et al. 1998).

Telehealth

Throughout the world, people living in rural and remote areas struggle to access timely, quality specialised medical care. Residents of these areas often have substandard access to specialised health care, primarily because specialist physicians are more likely to be located in metropolitan areas and large urban centres. Innovations in computing and telecommunications technology, however, have made it possible for many elements of medical practice to be accomplished when the patient and health care provider are geographically separated (Telemedicine Information Exchange 1999).

Telehealth or telemedicine refers to the delivery of health services at a distance through the transfer of information, including audio, video and graphic data, using telecommunications. Telehealth has been developing in Australia since the Flying Doctor Service used pedal radios to communicate with remote settlements from 1928 (http://www.rfds.org.au ). More recent years have seen a rapid expansion of telehealth services that provide for considerable reductions in cost for services to remote areas. Current telehealth activities in Australia encompass videoconferencing consultations, counselling and communication, medical image and data transfers, multidisciplinary and specialist support for health workers and clients, education and training, administration activities, access to databases for health workers and consumer information (ANZTC 1999). Because of telemedicine, geographical isolation need no longer be an insurmountable obstacle to the basic needs of timely and quality medical care (Telemedicine Information Exchange 1999).

Improving the quality of indoor environments

Australians will continue to spend over 90% of their time in indoor environments of various kinds. We are thus exposed to pollutants in buildings, outdoors and vehicles. In the past, environmental control has been on the basis of outdoor pollutant concentrations, but it is now realised that exposures in buildings and transit vehicles can be much more significant than outdoors. Risk assessment and control needs to be based on a total exposure assessment, the sum of exposures in all micro-environments that we live in.

To improve the indoor air quality of buildings, the challenges are twofold: to improve the ventilation in buildings and to increase the use of low-emission building products and appliances.

The mechanical ventilation rates of commercial buildings and the air infiltration rates of dwellings have been reduced over the last 15-20 years to conserve energy, but with detrimental effects on indoor air quality when indoor pollutant sources are significant.

The most effective way to control indoor pollutants is to limit their introduction into indoor environments by reducing emissions from source materials. Low-emission products are now manufactured for interior paints, reconstituted wood-based panels and unflued gas heaters, but the methods by which pollutant emissions from these products are assessed and the criteria by which emissions are considered 'low' are yet to be standardised and defined. CSIRO research has established preliminary test methods (Brown 1998a, 1999b, 1999c, 2000) that could form the basis of standards, but further research on risk assessment criteria is needed to establish acceptable product emission limits. These limits could then be used in green labelling schemes, an approach now gaining currency in other developed countries.