Defense
Student: Jose Angel Riandes González
Program: Meteorologia
Title: “The Impact of Heatwaves on the Risk of Cardiovascular and Respiratory Mortality Among the Elderly Population in California"
Advisor: Prof. Dr. Fábio Luiz Teixeira Gonçalves - IAG/USP
Judging Comitee:
- Prof. Dr. Fábio Luiz Teixeira Gonçalves – Presidente e Orientador - IAG/USP
- Dra. Samya de Lara Lins de Araujo Pinheiro – PETROBRAS (por videoconferência)
- Dra. Fernanda Rodrigues Diniz - CIELO
- Prof. Dr. Charles Jones - Universidade de Santa Barbara (por videoconferência)
- Prof. Dr. João Paulo Assis Gobo – UNIR (por videoconferência)
Abstract:
This study evaluates the impacts of heatwaves on mortality from cardiovascular
(CVD) and respiratory (RES) diseases among elderly individuals (≥ 65 years) in
California, combining statistical analysis of historical series (1986–2010) with
climate projections for the near (2051–2075) and distant (2076–2100) future under
RCP 4.5 and RCP 8.5 scenarios. Generalized additive Poisson models (GAM) and
distributed lag non-linear models (DLNM) were employed to estimate the relative
risk (RR) and excess mortality attributable to heat exposure, accounting for various
configurations of heatwave intensity and duration, as well as assumptions of
population adaptation and non-adaptation. Historically, counties such as Los
Angeles and Alameda exhibited declines in CVD mortality, while Fresno, Riverside,
and San Bernardino showed increasing trends in both CVD and RES mortality,
reflecting structural and environmental disparities. Heat Index (HI) exposure and
heatwave frequency were notably higher in inland counties. Under RCP 8.5,
projections indicate that Riverside may experience over 5,600 dangerous heat days
(HI > 54 °C) by 2100, while in San Bernardino, HI75 is projected to rise from
32.9 °C to 51.8 °C, significantly increasing physiological stress. RR analysis revealed
that coastal counties are more sensitive to peak thermal intensity (main effect) for
CVD, whereas inland counties are more vulnerable to prolonged heat exposure
(added effect). For RES, added effects predominated across nearly all counties, with
San Bernardino reaching the highest RR = 1.30 (95% CI: 0.99–1.70). Historical
excess mortality due to CVD peaked at 10.86 deaths per 100,000 in Los Angeles
(2-day events, P90). In future projections without adaptation, excess RES mortality
may exceed 351.7 per 100,000 in Riverside and 230.1 per 100,000 in San
Bernardino. Future simulations show that adaptation measures could limit excess
mortality to ≤ 13 per 100,000 in most counties. In their absence, excess deaths
increase dramatically—up to 150/100,000 in Fresno and over 400/100,000 in
Riverside during prolonged heatwaves under RCP 8.5. Even with adaptation, Los
Angeles faces elevated impacts (up to 44/100,000 in short events). These findings
underscore the urgency of implementing regional mitigation and adaptation
strategies—including early warning systems, cooling centers, accessible air
conditioning, and pollution control. Without such interventions, heatwaves may
evolve into severe public health crises in California’s hottest and most socially
vulnerable areas.
Keywords: Heatwaves; Cardiovascular Diseases; Respiratory Diseases; Relative Risk; Excess
Mortality; Future Scenarios.