Shifts in the seasonal distribution of deaths in Australia, 1968-2007.

Studies in temperate countries have shown that both hot weather in summer and cold weather in winter increase short-term (daily) mortality. The gradual warming, decade on decade, that Australia has experienced since the 1960s, might therefore be expected to have differentially affected mortality in the two seasons, and thus indicate an early impact of climate change on human health. Failure to detect such a signal would challenge the widespread assumption that the effect of weather on mortality implies a similar effect of a change from the present to projected future climate. We examine the ratio of summer to winter deaths against a background of rising average annual temperatures over four decades: the ratio has increased from 0.71 to 0.86 since 1968. The same trend, albeit of varying strength, is evident in all states of Australia, in four age groups (aged 55 years and above) and in both sexes. Analysis of cause-specific mortality suggests that the change has so far been driven more by reduced winter mortality than by increased summer mortality. Furthermore, comparisons of this seasonal mortality ratio calculated in the warmest subsets of seasons in each decade, with that calculated in the coldest seasons, show that particularly warm annual conditions, which mimic the expected temperatures of future climate change, increase the likelihood of higher ratios (approaching 1:1). Overall, our results indicate that gradual climate change, as well as short-term weather variations, affect patterns of mortality.

Associations between ambient PM2.5 concentrations and respiratory symptoms in Melbourne, 1998-2005.

Particulate matter (PM) has been widely associated with adverse effects on respiratory health, both overseas and in Australia. This study aimed to investigate the impacts of ambient particles of <2.5 microm diameter (PM2.5) in Melbourne on adverse respiratory symptoms. Two cohorts of adults were recruited in 1992-1998, and completed detailed respiratory questionnaires in 1998-1999 and 2004-2005. The mean age at baseline was 37.2 years, 55% were female, and the mean time lapsed between the baseline and follow-up questionnaires was 5.2 years. PM2.5 exposure was assessed from gravimetric data and routine nephelometry at monitoring stations located centrally with respect to the residence of most participants. Daily exposures to PM2.5 were averaged over the previous 12 months and mean daily exposure was 6.8 microg/m3. Logistic regression models were used to examine associations between PM2.5 exposure and adverse respiratory symptoms. Adjustment was made for age, gender, current smoking status, and medication use, but further adjustment for atopy did not alter the results. There was insufficient variability in PM2.5 exposure among participants over the study period to provide convincing evidence for or against associations between PM2.5 and adverse respiratory symptoms.

The Importance of Humidity in the Relationship between Heat and Population Mental Health: Evidence from Australia.

Despite many studies on the effects of heat on mental health, few studies have examined humidity. In order to investigate the relationship among heat, humidity and mental health, we matched data from the Social, Economic and Environmental Factors (SEEF) project with gridded daily temperature and water vapour pressure data from the Australian Bureau of Meteorology. Logit models were employed to describe the associations among heat (assessed using temperature, °C), humidity (assessed using vapour pressure, hPa) and two measures of mental health, (i) high or very high distress (assessed using K10 scores ≥ 22) and (ii) having been treated for depression or anxiety. We found a one-unit increase in temperature and vapour pressure was associated with an increase in the occurrence of high or very high distress by 0.2% (p < 0.001, 99% CI: 0.1-0.3%) and 0.1% (p < 0.001, 99% CI: 0.0-0.3%) respectively. However, when humidity rose to the 99th percentile of the sample, the estimated marginal effect of heat was more than doubled (0.5%, p < 0.001, 99% CI: 0.2-0.7%). Neither heat nor humidity was related to having been treated for depression or anxiety in the last month. Humidity compounds the negative association between hot weather and mental health and thus should be taken into account when reforming the health care system to respond to the challenge of climate change.

Impacts of Climate Change on Inequities in Child Health.

This paper addresses an often overlooked aspect of climate change impacts on child health: the amplification of existing child health inequities by climate change. Although the effects of climate change on child health will likely be negative, the distribution of these impacts across populations will be uneven. The burden of climate change-related ill-health will fall heavily on the world's poorest and socially-disadvantaged children, who already have poor survival rates and low life expectancies due to issues including poverty, endemic disease, undernutrition, inadequate living conditions and socio-economic disadvantage. Climate change will exacerbate these existing inequities to disproportionately affect disadvantaged children. We discuss heat stress, extreme weather events, vector-borne diseases and undernutrition as exemplars of the complex interactions between climate change and inequities in child health.

Climate change, aeroallergens, natural particulates, and human health in Australia: state of the science and policy.

The objective of this article is to systematically review and assess what is known about the impacts of climate change on aeroallergens and other naturally derived particulates, and the associated human health impacts, and to examine responses to these in Australia, focusing on adaptation. Prior research was searched using several general and discipline-specific research databases. The review concludes that whereas there is little original research on the impacts of climate change on aeroallergens and other naturally derived particulates in Australia, or the human health consequences of these, research from overseas suggests that these impacts may be adverse and of considerable magnitude. More research is required to assess the impacts of climate change on these airborne particles and associated diseases in Australia and other parts of the Asia-Pacific. There are important policy implications of this review. There is a need for enhanced monitoring of the atmospheric environment and associated health conditions in Australia. Education about climate change and human health in general, and air quality and related diseases specifically, is required for the community, health professionals, and others. Improvements are needed in the preparedness of infrastructure, such as health care facilities and early warning systems, particularly for aeroallergens, and all of these adaptive policy responses require further research.

Climate change and rising heat: population health implications for working people in Australia.

The rapid rise in extreme heat events in Australia recently is already taking a health toll. Climate change scenarios predict increases in the frequency and intensity of extreme heat events in the future, and population health may be significantly compromised for people who cannot reduce their heat exposure. Exposure to extreme heat presents a health hazard to all who are physically active, particularly outdoor workers and indoor workers with minimal access to cooling systems while working. At air temperatures close to (or beyond) the core body temperature of 37°C, body cooling via sweating is essential, and this mechanism is hampered by high air humidity. Heat exposure among elite athletes and the military has been investigated, whereas the impacts on workers remain largely unexplored, particularly in relation to future climate change. Workers span all age groups and diverse levels of fitness and health status, including people with higher than "normal" sensitivity to heat. In a hotter world, workers are likely to experience more heat stress and find it increasingly difficult to maintain productivity. Modeling of future climate change in Australia shows a substantial increase in the number of very hot days (>35°C) across the country. In this article, the authors characterize the health risks associated with heat exposure on working people and discuss future exposure risks as temperatures rise. Progress toward developing occupational health and safety guidelines for heat in Australia are summarized.

Non-heat related impacts of climate change on working populations.

Environmental and social changes associated with climate change are likely to have impacts on the well-being, health, and productivity of many working populations across the globe. The ramifications of climate change for working populations are not restricted to increases in heat exposure. Other significant risks to worker health (including physical hazards from extreme weather events, infectious diseases, under-nutrition, and mental stresses) may be amplified by future climate change, and these may have substantial impacts at all scales of economic activity. Some of these risks are difficult to quantify, but pose a substantial threat to the viability and sustainability of some working populations. These impacts may occur in both developed and developing countries, although the latter category is likely to bear the heaviest burden.This paper explores some of the likely, non-heat-related health issues that climate change will have on working populations around the globe, now and in the future. These include exposures to various infectious diseases (vector-borne, zoonotic, and person-to-person), extreme weather events, stress and mental health issues, and malnutrition.