Thermal variability and the geography of optimal temperature for child survival: childhood respiratory-infection mortality in 171 countries: a systematic analysis of the Global Burden of Disease Study 2023 and the C-LSAT high-resolution climate dataset
- 1National Center for Children's Health, Beijing Children's Hospital, Capital Medical University, Beijing, China
Abstract
BackgroundIn adults, cold-attributable mortality exceeds heat-attributable mortality roughly 17-fold. Child-specific evidence has begun to emerge only recently--a nationwide Brazilian case-crossover study located the minimum mortality temperature (MMT) for under-five deaths, and a 56-country survey-based analysis linked monthly temperature anomalies to under-five mortality--but no multi-country, climate-zone-resolved estimate of the childhood respiratory-infection MMT exists, and whether temperature variability is independently associated with childhood respiratory mortality at the global scale is unknown. We quantified both.
MethodsWe combined Global Burden of Disease 2023 mortality estimates--lower respiratory infection (LRI) deaths at ages 0-19 years and asthma deaths at ages 0-24 years, 171 countries, 1990-2023--with 0.5{degrees} monthly land temperature and diurnal temperature range (DTR) fields from C-LSAT/C-LDTR (1901-2023). Four exposure dimensions (annual mean, DTR, seasonal amplitude, interannual variability) entered two-way fixed-effects models with Driscoll-Kraay standard errors. A quadratic term in mean temperature located the MMT, with percentile confidence intervals from a 300-replication country-cluster bootstrap. Future-exposure leads, country-level detrending, and permutation tests assessed contemporaneous causality, applied to both the linear coefficients and the quadratic term generating the MMT; national pneumococcal conjugate vaccine (PCV3) coverage and ambient PM2.5 exposure series were added as time-varying mechanistic covariates.
ResultsThe childhood LRI MMT was 17.1 {degrees}C (95% CI 14.7-19.8), the 36th percentile of the annual-temperature distribution; zone estimates were 24.7 {degrees}C in tropical and 15.8 {degrees}C in subtropical countries, with weak temperate and no subarctic identification. The quadratic term underpinning the MMT, however, failed both falsification checks--future temperatures reproduced the U-shape and country-level detrending erased it--so these MMT values describe a trend-level geographic pattern of the annual construct rather than a contemporaneous dose- response. Interannual temperature variability was positively associated with LRI (+0.278, 95% CI 0.102-0.454; p = 0.002) and asthma mortality (+0.836, 95% CI 0.447-1.226; p = 2.6 x 10{square}{square}) per 1 {degrees}C, but future-exposure models returned nearly identical significant coefficients and detrending erased significance, supporting only a trend-level association; adjustment for national PCV3 coverage and PM2.5 exposure left these estimates essentially unchanged. Annual mean temperature was likewise inversely associated with both outcomes at the trend level; DTR and seasonal amplitude showed no independent within-country effects.
ConclusionsThis study provides the first multi-country, climate-zone-resolved geography of the optimal temperature for childhood respiratory survival, spanning 171 countries; because the underlying quadratic association is trend-level, the estimates are directional. The observed variability-mortality associations are trend-level signals rather than contemporaneous causal evidence; daily-scale, child-specific designs are required to determine whether short-term thermal variability affects paediatric respiratory mortality.
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BibTeX
@misc{li2026thermal,
title = {{Thermal variability and the geography of optimal temperature for child survival: childhood respiratory-infection mortality in 171 countries: a systematic analysis of the Global Burden of Disease Study 2023 and the C-LSAT high-resolution climate dataset}},
author = {D. Li and J. Liu and S. Sun and H. Chen and W. Shen and X. Wang and C. Shen},
howpublished = {medRxiv},
year = {2026},
month = aug,
doi = {10.64898/2026.08.31.26361864},
url = {https://www.medrxiv.org/content/10.64898/2026.08.31.26361864v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Thermal variability and the geography of optimal temperature for child survival: childhood respiratory-infection mortality in 171 countries: a systematic analysis of the Global Burden of Disease Study 2023 and the C-LSAT high-resolution climate dataset
AU - D. Li
AU - J. Liu
AU - S. Sun
AU - H. Chen
AU - W. Shen
AU - X. Wang
AU - C. Shen
PY - 2026
DA - 2026/08/31
PB - medRxiv
DO - 10.64898/2026.08.31.26361864
UR - https://www.medrxiv.org/content/10.64898/2026.08.31.26361864v1
AB - BackgroundIn adults, cold-attributable mortality exceeds heat-attributable mortality roughly 17-fold. Child-specific evidence has begun to emerge only recently--a nationwide Brazilian case-crossover study located the minimum mortality temperature (MMT) for under-five deaths, and a 56-country survey-based analysis linked monthly temperature anomalies to under-five mortality--but no multi-country, climate-zone-resolved estimate of the childhood respiratory-infection MMT exists, and whether temperature variability is independently associated with childhood respiratory mortality at the global scale is unknown. We quantified both. MethodsWe combined Global Burden of Disease 2023 mortality estimates--lower respiratory infection (LRI) deaths at ages 0-19 years and asthma deaths at ages 0-24 years, 171 countries, 1990-2023--with 0.5{degrees} monthly land temperature and diurnal temperature range (DTR) fields from C-LSAT/C-LDTR (1901-2023). Four exposure dimensions (annual mean, DTR, seasonal amplitude, interannual variability) entered two-way fixed-effects models with Driscoll-Kraay standard errors. A quadratic term in mean temperature located the MMT, with percentile confidence intervals from a 300-replication country-cluster bootstrap. Future-exposure leads, country-level detrending, and permutation tests assessed contemporaneous causality, applied to both the linear coefficients and the quadratic term generating the MMT; national pneumococcal conjugate vaccine (PCV3) coverage and ambient PM2.5 exposure series were added as time-varying mechanistic covariates. ResultsThe childhood LRI MMT was 17.1 {degrees}C (95% CI 14.7-19.8), the 36th percentile of the annual-temperature distribution; zone estimates were 24.7 {degrees}C in tropical and 15.8 {degrees}C in subtropical countries, with weak temperate and no subarctic identification. The quadratic term underpinning the MMT, however, failed both falsification checks--future temperatures reproduced the U-shape and country-level detrending erased it--so these MMT values describe a trend-level geographic pattern of the annual construct rather than a contemporaneous dose- response. Interannual temperature variability was positively associated with LRI (+0.278, 95% CI 0.102-0.454; p = 0.002) and asthma mortality (+0.836, 95% CI 0.447-1.226; p = 2.6 x 10{square}{square}) per 1 {degrees}C, but future-exposure models returned nearly identical significant coefficients and detrending erased significance, supporting only a trend-level association; adjustment for national PCV3 coverage and PM2.5 exposure left these estimates essentially unchanged. Annual mean temperature was likewise inversely associated with both outcomes at the trend level; DTR and seasonal amplitude showed no independent within-country effects. ConclusionsThis study provides the first multi-country, climate-zone-resolved geography of the optimal temperature for childhood respiratory survival, spanning 171 countries; because the underlying quadratic association is trend-level, the estimates are directional. The observed variability-mortality associations are trend-level signals rather than contemporaneous causal evidence; daily-scale, child-specific designs are required to determine whether short-term thermal variability affects paediatric respiratory mortality.
ER -