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Background: This paper examines the short-term health effects of air pollution on daily hospital admissions in Australian cities (those considered comprise more than 50% of the Australian population) for the period 1996-99. Methods: The study used a similar protocol to overseas studies and derived single city and pooled estimates using different statistical approaches to assess the accuracy of the results. Results: There was little difference between the results derived from the different statistical approaches for cardiovascular admissions, while in those for respiratory admissions there were differences. For three of the four cities (for the other the results were positive but not significant), fine particles (measured by nephelometry--bsp) and nitrogen dioxide (N[O.sub.2]) have a significant impact on cardiovascular admissions (for total cardiac admissions, RR=1.0856 for a one-unit increase in bsp ([10.sup.-4].[m.sup.-1]), RR=1.0023 for a 1 ppb increase in N[O.sub.2]). For three of the four cities (for the other, the results were negative and significant), fine particles, N[O.sub.2] and ozone have a significant impact on respiratory admissions (for total elderly respiratory admissions, RR=1.0552 per 1 unit ([10.sup-4].[m.sup.-1]) increase in bsp, RR=1.0027 per 1ppb increase in N[O.sub.2], RR=10014 per 1 ppb increase in ozone for elderly asthma and COPD admissions). In all analyses the particle and N[O.sub.2] impacts appear to be related. Conclusions: Similar to overseas studies, air pollution has an impact on hospital admissions in Australian cities, but there can be significant differences between cities.

Objective: To examine the short-term health effects of air pollution on daily mortality in four Australian cities (Brisbane, Melbourne, Perth and Sydney), where more than 50% of Australians reside. Methods: The study used a similar protocol to APHEA2 (Air Pollution and Health: A European Approach) study and derived single-city and pooled estimates. Results: The results derived from the different approaches for the 1996-99 period showed consistent results for different statistical models used. There were significant effects on total mortality, (RR=1.0284 per 1 unit increase in nephelometry [[10.sup.-4].[m.sup.-1]], RR=1.0011 per 1 ppb increase in N[O.sub.2]), and on respiratory mortality (RR=1.0022 per 1ppb increase in [O.sub.3]). No significant differences between cities were found, but the N[O.sub.2] and particle effects may refer to the same impacts. Meta-analyses carried out for three cities yielded estimates for the increase in the daily total number of deaths of 0.2% (-0.8% to 1.2%) for a 10 [micro]g/[m.sup.3] increase in P[M.sub.10] concentration, and 0.9% (-0.7% to 2.5%) for a 10 [micro]g/[m.sup.3] increase in P[M.sub.2.5] concentration. Conclusions: Air pollutants in Australian cities have significant effects on mortality.

The association between ambient temperature and lung function in children with asthma is still uncertain. A panel of 270 children (aged 7-12 years) with asthma was recruited from six Australian cities. They performed three successive forced expiratory manoeuvres twice daily for 4 weeks. The highest peak expiratory flow rate (PEF) and forced expiratory volume in 1 s (FEV1) were stored for each session. During the same period, data were obtained daily on ambient temperature, relative humidity and air pollution. Mixed models were used to examine the effects of temperature on lung function, controlling for individual characteristics and environmental factors. Ambient temperature was negatively related to both morning and evening PEF and FEV1 for 0-3 days lag. In general, the effects of temperature were stronger in males than in females for evening PEF, while the effects were stronger in females for evening FEV1. Children with asthma living in southern cities were more sensitive to high temperature than those in the northernmost city. Higher ambient temperature is associated with lower lung function in children with asthma. Preventive health policies will be required to protect children with asthma from increasingly frequent high temperatures.