Cold Spells Linked to Pediatric Asthma in Coastal Australia

A twenty-year observational study conducted in Queensland, Australia, has identified distinct associations between extreme temperature events and hospitalizations for asthma among children and adolescents. The research, published in BMC Public Health, analyzed weekly hospitalization data from two coastal cities with different thermal environments: Cairns, a tropical city, and Brisbane, a subtropical city. By focusing on children and adolescents aged five to nineteen years, the study provides a long-term perspective on how extreme weather conditions may influence respiratory health in vulnerable populations living in coastal regions.

The investigators utilized the Universal Thermal Climate Index, or UTCI, to define cold spells and heat waves, offering a standardized metric for assessing extreme thermal conditions. Over the two-decade period from 2000 to 2019, these extreme events occurred during approximately six to ten percent of weekly observations across the Statistical Area Level 2 regions in both cities. The study employed multilevel negative binomial regression models with random intercepts to examine the relationship between these weather events and asthma hospitalization rates, allowing for the analysis of complex data structures and regional variations.

In models adjusted for sulfur dioxide, a key air pollutant, the results indicated that cold spells were associated with increased asthma hospitalization rates in both cities. In Brisbane, the relative risk was 1.11, with a 95 percent confidence interval ranging from 1.03 to 1.19, suggesting a statistically significant increase in hospitalizations during cold spell weeks. In Cairns, the relative risk was 1.18, with a confidence interval of 0.99 to 1.41, indicating a similar positive association, although the precision of this estimate was lower. These findings highlight the potential impact of cold extreme weather on pediatric asthma outcomes in both tropical and subtropical coastal settings.

Conversely, the study found inverse associations between heat waves and asthma hospitalizations in Brisbane, where the relative risk was 0.84, with a 95 percent confidence interval of 0.78 to 0.90. This suggests that heat wave weeks were associated with a lower rate of asthma hospitalizations in the subtropical city. In Cairns, the heat wave estimate was 0.82, but the confidence interval of 0.65 to 1.04 indicated that this association was imprecise and not statistically significant. The varying results between the two cities underscore the importance of considering local thermal environments when assessing the health impacts of extreme weather.

The researchers also conducted stratified analyses to explore how age, sex, socioeconomic status, and land-cover characteristics might modify these associations. Formal interaction tests revealed age-related effect modification in Brisbane for both cold spells and heat waves, with p-values of 0.007 and 0.045, respectively. This suggests that the impact of extreme temperature events on asthma hospitalizations may differ depending on the age of the child or adolescent. However, interactions for other subgroups, such as sex and socioeconomic status, were not statistically significant, indicating that the primary associations were consistent across these demographic groups.

Between-city heterogeneity tests did not provide statistical evidence that the city-specific estimates differed significantly, suggesting that the overall patterns of association were similar in both Cairns and Brisbane. Nevertheless, the precision of the estimates varied, with some associations being more robust in one city than the other. The study also adjusted for other air pollutants, including nitrogen dioxide and particulate matter with a diameter of 2.5 micrometers or less, to account for potential confounding effects. The direction of the associations remained largely consistent across these different pollutant-adjustment models, although some estimates showed attenuation, particularly for heat waves.

Sensitivity analyses using alternative percentile thresholds and consecutive-day criteria for defining extreme weather events showed greater variability in some estimates, particularly for cold spells in Cairns. This suggests that the specific definition of extreme weather events can influence the observed associations. Distributed lag models were also employed to examine the timing of the associations, revealing positive cold-spell estimates at lag zero and inverse heat-wave estimates over short lags. These patterns varied by city and pollutant model, indicating that the immediate and short-term effects of extreme weather on asthma hospitalizations may differ depending on the local context.

The findings of this study suggest that UTCI-defined extreme temperature events are associated with pediatric asthma hospitalizations in coastal Queensland, with cold spells generally linked to increased hospitalizations and heat waves showing more variable and sometimes inverse associations. The long-term nature of the study and the inclusion of two cities with different thermal environments provide valuable insights into the complex relationship between extreme weather and respiratory health in children.

Subject of Research: Association between extreme temperature events and pediatric asthma hospitalizations in coastal Queensland, Australia

Article Title: Extreme weather and paediatric asthma hospitalisations: a 20-year study in tropical and subtropical coastal cities

Article References: Wang, J., Cortes-Ramirez, J., Davies, J. M., & Hu, W. (2026). Extreme weather and paediatric asthma hospitalisations: a 20-year study in tropical and subtropical coastal cities. BMC Public Health. https://doi.org/10.1186/s12889-026-29584-3

Image Credits: AI Generated

DOI: 10.1186/s12889-026-29584-3

Keywords: pediatric asthma, extreme weather, cold spells, heat waves, coastal cities, Queensland, hospitalizations, climate health, UTCI, respiratory health, Extreme, weather