Anthropogenic climate change and health in the Global South.

This paper explores evidence relevant to the hypothesis that human-generated climate change (global warming) is already, and will increasingly, add to the existing burden of disadvantage experienced by populations in low-income countries, the 'Global South'. Well recognised health manifestations of global warming include from heatwaves and other extreme weather events, changes to infectious disease patterns, and undernutrition, arising from higher food prices, reduced food availability and reduced nutrient concentrations of many foods. These effects have been called 'primary' and 'secondary'. Although these manifestations will have effects globally, their biggest impact on health is and will be upon poor and vulnerable populations in low-income settings. Also well recognised, manual labourers are increasingly vulnerable from excessive heat and humidity. There is less recognition that climate change interacts with social and political determinants of health, contributing to 'tertiary' health consequences including conflict, forced migration and famine. In turn, these effects may deepen poverty traps in the Global South. Human-generated climate change is principally caused by the policies and lifestyles of populations in high-income countries (the Global North). The recent recognition by the British government that climate change is an emergency is encouraging, and may help motivate the widespread global behavioural changes that are needed to reduce the many risks from global warming, including to the people of the South.

Drought as a mental health exposure.

The mental health impact of drought is poorly quantified and no previous research has demonstrated a relationship between distress and explicit environmentally based measures of drought. With continuing climate change, it is important to understand what drought is and how it may affect the mental health. We quantified drought in terms of duration and intensity of relative dryness and identified drought characteristics associated with poor mental health to evaluate any vulnerability in rural and urban communities. Our methods involved analysis of 100-year longitudinal records of monthly rainfall linked to one wave (2007-2008) of the Household, Income and Labour Dynamics in Australia Survey. Cluster analysis was used to characterise different patterns of dryness and linear regression analysis was used to examine associations with participant distress, as well as the moderating role of rural locality. The results showed that, during a seven-year period of major and widespread drought, one pattern of relative dryness (extreme cumulative number of months in drought culminating in a recent period of dryness lasting a year or more) was associated with increased distress for rural but not urban dwellers. The increase in distress was estimated to be 6.22%, based on 95% confidence intervals. Thus, we show that it is possible to quantitatively identify an association between patterns of drought and distress.

The influence of weather on community gastroenteritis in Australia.

Infectious gastroenteritis is a common illness in Australia as elsewhere. Data from a year-long national gastroenteritis survey in 2001-2002 showed that gastroenteritis was more common in the northern and hotter part of Australia. These data were used to quantify associations between local weather variables and gastroenteritis in people aged >5 years while controlling for socioeconomic status. A distributed lag model was used to examine the influence of weather over a period of days prior to an event and the maximal effect was found at a lag of 2-5 days. The total effect over the preceding week indicated a relative increase from baseline in the probability of gastroenteritis of 2·48% (95% CI 1·01-3·97) for each degree rise (°C) over that period. Given the very high burden of gastroenteritis, this represents a substantial effect at the population level and has relevance for health predictions due to climate change.

Respiratory hospital admissions were associated with ambient airborne pollen in Darwin, Australia, 2004-2005.

BACKGROUND: Although the role of pollen and fungus in specific allergic disorders has been well established, the public health impacts of ambient concentrations of airborne pollen and fungal spores; the shapes of concentration-response relationships; and the relative effects of different taxa are gaps in current knowledge. OBJECTIVE: To investigate associations between daily average ambient pollen and fungal spore concentrations with hospital admissions for total respiratory diseases; asthma; chronic obstructive pulmonary disease (COPD); and respiratory infections in Darwin, Australia, during the period from April 2004 to November 2005. METHODS: We assessed these relationships in a two-stage modelling approach designed to quantify potential non-linear relationships. First, generalized additive models determined the shapes of concentration-response relationships. Second, linear associations were examined using generalized linear models. Non-linear relationships were analysed by categorizing pollen and fungal spore concentrations based on their distributions. RESULTS: Positive linear associations were found between total pollen concentrations and hospital admissions for total respiratory diseases and COPD. While our exploratory first-stage analysis suggested non-linear relationships for total pollen with asthma and respiratory infections, no convincing evidence for these relationships was found in the second-stage analysis. When individual taxa were investigated, associations were the strongest in relation to Myrtaceae pollen (the dominant tree taxa in the region), while positive associations not attaining statistical significance were observed for Poaceae, Cyperaceae and Arecaceae. No associations were evident for any conditions with fungal spores. CONCLUSIONS: Our finding of an association between pollen count and respiratory hospital admissions that could not be explained by asthma admissions suggests that ambient airborne pollens might have a wider public health impact than previously recognized.