Working with Climate Projections to Estimate Disease Burden: Perspectives from Public Health

There is interest among agencies and public health practitioners in the United States (USA) to estimate the future burden of climate-related health outcomes. Calculating disease burden projections can be especially daunting, given the complexities of climate modeling and the multiple pathways by which climate influences public health. Interdisciplinary coordination between public health practitioners and climate scientists is necessary for scientifically derived estimates. We describe a unique partnership of state and regional climate scientists and public health practitioners assembled by the Florida Building Resilience Against Climate Effects (BRACE) program. We provide a background on climate modeling and projections that has been developed specifically for public health practitioners, describe methodologies for combining climate and health data to project disease burden, and demonstrate three examples of this process used in Florida

Environmental Predictors of Seasonal Influenza Epidemics across Temperate and Tropical Climates

Human influenza infections exhibit a strong seasonal cycle in temperate regions. Recent laboratory and epidemiological evidence suggests that low specific humidity conditions facilitate the airborne survival and transmission of the influenza virus in temperate regions, resulting in annual winter epidemics. However, this relationship is unlikely to account for the epidemiology of influenza in tropical and subtropical regions where epidemics often occur during the rainy season or transmit year-round without a well-defined season. We assessed the role of specific humidity and other local climatic variables on influenza virus seasonality by modeling epidemiological and climatic information from 78 study sites sampled globally. We substantiated that there are two types of environmental conditions associated with seasonal influenza epidemics: “cold-dry” and “humid-rainy”. For sites where monthly average specific humidity or temperature decreases below thresholds of approximately 11–12 g/kg and 18–21°C during the year, influenza activity peaks during the cold-dry season (i.e., winter) when specific humidity and temperature are at minimal levels. For sites where specific humidity and temperature do not decrease below these thresholds, seasonal influenza activity is more likely to peak in months when average precipitation totals are maximal and greater than 150 mm per month. These findings provide a simple climate-based model rooted in empirical data that accounts for the diversity of seasonal influenza patterns observed across temperate, subtropical and tropical climates

Verifying Experimental Wet Bulb Globe Temperature Hindcasts Across the United States

Hot and humid heat exposures challenge the health of outdoor workers engaged in occupations such as construction, agriculture, first response, manufacturing, military, or resource extraction. Therefore, government institutes developed guidelines to prevent heat-related illnesses and death during high heat exposures. The guidelines use Wet Bulb Globe Temperature (WBGT), which integrates temperature, humidity, solar radiation, and wind speed. However, occupational heat exposure guidelines cannot be readily applied to outdoor work places due to limited WBGT validation studies. In recent years, institutions have started providing experimental WBGT forecasts. These experimental products are continually being refined and have been minimally validated with ground-based observations. This study evaluated a modified WBGT hindcast using the historical National Digital Forecast Database and the European Centre for Medium-Range Weather Forecasts Reanalysis v5. We verified the hindcasts with hourly WBGT estimated from ground-based weather observations. After controlling for geographic attributes and temporal trends, the average difference between the hindcast and in situ data varied from −0.64°C to 1.46°C for different Köppen-Geiger climate regions, and the average differences are reliable for decision making. However, the results showed statistically significant variances according to geographical features such as aspect, coastal proximity, land use, topographic position index, and Köppen-Geiger climate categories. The largest absolute difference was observed in the arid desert climates (1.46: 95% CI: 1.45, 1.47), including some parts of Nevada, Arizona, Colorado, and New Mexico. This research investigates geographic factors associated with systematic WBGT differences and points toward ways future forecasts may be statistically adjusted to improve accuracy

Spatial disparities in air conditioning ownership in Florida, United States

ABSTRACTThis study emphasizes the critical role of air conditioning (AC) in preventing heat-related illnesses such as heat exhaustion and heatstroke. The challenge of limited geographic coverage and outdated AC availability data hampers effective heat risk mapping and prevention efforts. We identified areas with significant AC needs and examined factors related to AC ownership in Florida, U.S. Local Indicators of Spatial Association results displayed distinct AC ownership disparities, with high-high clusters in coastal and metropolitan areas and AC-deficient clusters inland. Vulnerable urban communities, predominantly inhabited by marginalized groups, had limited to no AC availability. The Spatial Durbin Model results revealed a significant correlation between AC ownership and socioeconomic and urban factors. Notably, a higher proportion of AC-deficient households were in predominantly African-American neighborhoods, underscoring racial disparities in AC ownership. These findings provide valuable insights for targeted interventions to mitigate heat-related risks and adapt to evolving climate conditions in vulnerable neighborhoods

Climatic Influences on Cryptococcus gattii Populations, Vancouver Island, Canada, 2002–2004

Vancouver Island, Canada, reports the world’s highest incidence of Cryptococcus gattii infection among humans and animals. To identify key biophysical factors modulating environmental concentrations, we evaluated monthly concentrations of C. gatti in air, soil, and trees over a 3-year period. The 2 study datasets were repeatedly measured plots and newly sampled plots. We used hierarchical generalized linear and mixed effect models to determine associations. Climate systematically influenced C. gattii concentrations in all environmental media tested; in soil and on trees, concentrations decreased when temperatures were warmer. Wind may be a key process that transferred C. gattii from soil into air and onto trees. C. gattii results for tree and air samples were more likely to be positive during periods of higher solar radiation. These results improve the understanding of the places and periods with the greatest C. gattii colonization. Refined risk projections may help susceptible persons avoid activities that disturb the topsoil during relatively cool summer days

Spatial disparities in air conditioning ownership in Florida, United States

This study emphasizes the critical role of air conditioning (AC) in preventing heat-related illnesses such as heat exhaustion and heatstroke. The challenge of limited geographic coverage and outdated AC availability data hampers effective heat risk mapping and prevention efforts. We identified areas with significant AC needs and examined factors related to AC ownership in Florida, U.S. Local Indicators of Spatial Association results displayed distinct AC ownership disparities, with high-high clusters in coastal and metropolitan areas and AC-deficient clusters inland. Vulnerable urban communities, predominantly inhabited by marginalized groups, had limited to no AC availability. The Spatial Durbin Model results revealed a significant correlation between AC ownership and socioeconomic and urban factors. Notably, a higher proportion of AC-deficient households were in predominantly African-American neighborhoods, underscoring racial disparities in AC ownership. These findings provide valuable insights for targeted interventions to mitigate heat-related risks and adapt to evolving climate conditions in vulnerable neighborhoods.</p

Environmental Predictors of Seasonal Influenza Epidemics across Temperate and Tropical Climates

<div><p>Human influenza infections exhibit a strong seasonal cycle in temperate regions. Recent laboratory and epidemiological evidence suggests that low specific humidity conditions facilitate the airborne survival and transmission of the influenza virus in temperate regions, resulting in annual winter epidemics. However, this relationship is unlikely to account for the epidemiology of influenza in tropical and subtropical regions where epidemics often occur during the rainy season or transmit year-round without a well-defined season. We assessed the role of specific humidity and other local climatic variables on influenza virus seasonality by modeling epidemiological and climatic information from 78 study sites sampled globally. We substantiated that there are two types of environmental conditions associated with seasonal influenza epidemics: “cold-dry” and “humid-rainy”. For sites where monthly average specific humidity or temperature decreases below thresholds of approximately 11–12 g/kg and 18–21°C during the year, influenza activity peaks during the cold-dry season (i.e., winter) when specific humidity and temperature are at minimal levels. For sites where specific humidity and temperature do not decrease below these thresholds, seasonal influenza activity is more likely to peak in months when average precipitation totals are maximal and greater than 150 mm per month. These findings provide a simple climate-based model rooted in empirical data that accounts for the diversity of seasonal influenza patterns observed across temperate, subtropical and tropical climates.</p> </div

Climate and Health Technical Report Series: Climate and Health Program, Centers for Disease Control and Prevention

This is a report by the Centers for Disease Control and Prevention is on the Building Resilience Against Climate Effects (BRACE) to aid departments prepare for and respond to climate change in Georgia