Evaluating the burden of climate-related respiratory disease using high resolution spatiotemporal models

The average global temperature has increased by about 0.8C since 1880. Contributors to this temperature change include greenhouse gas emissions from agriculture and land, sea, and air transportation. The impact of climate change on health-in particular respiratory diseases-can be direct or indirect. Direct impact refers to an increasing number of deaths and hospitalizations due to extreme temperature events, heatwaves, while indirect impact involves promoting factors such as air pollution that are known to increase deaths or hospitalizations for respiratory disease. According to climate modelers, temperatures will continue to increase unless we implement strategies to decrease greenhouse gas and other pollutant emissions. The aim of this project is to develop comprehensive statistical models and quantify the effect of extreme temperatures with respect to respiratory health. To do this, I will first use nationwide data in the UK and also focus on the four most populous cities which, due to high buildings, overcrowding, and poor air quality are known to experience higher temperatures than neighboring rural areas. Using different emissions scenarios, I will predict future respiratory hospitalization due to climate change, and also quantify corresponding costs. I will also examine how increasing the land area of green spaces in cities, for example by planting trees, can help decrease future respiratory deaths and hospitalizations. Finally, I will make my results publicly available by creating a website with maps of future respiratory hospitalization and related costs due to climate change. The proposed research will take place at MRC Centre for Environment and Health under the supervision of Prof Blangiardo. This international interdisciplinary project includes a health economist (Prof Baio), statisticians (Prof Schuhmacher, Dr Gasparrini, and Dr Bhatt), epidemiologists (Dr Vicedo-Cabrera and Dr Minelli) and a climate change modeller (Dr Ballester). This work will be one of the first such projects to provide an integrated framework to quantify the health effects and costs of temperature changes in the UK on a nationwide level at a small-area scale. I will pay particular attention to communicating the results among public health experts and the general public via a website. This methodology will be transferable to other drivers of disease affected by climate change such as infectious diseases in more vulnerable areas such as developing countries.

The Earth's climate is changing and temperature levels across the globe are rising as anthropogenic factors including greenhouse gas (GHG) emissions from transportation, power generation and other uses of fossil fuels warm the planet. Changes in temperature could aggravate respiratory diseases directly or by exacerbating the effects of factors such as ozone that are associated with these diseases. Recent projections of future GHG emissions predict a mean temperature increase between 1.1 and 6.4C by the end of the 21st century. Most previous studies have focused on mortality using aggregated data. They employed time series models using temperature projections at low geographical resolution, ignoring local temperature fluctuations such as the effect of urban heat islands in which urban areas are warmer than their surroundings. In addition, the health impact and costs of climate-sensitive diseases have received hardly any attention so far. The aim of this project is to develop a framework of analysis based on high-resolution Bayesian spatiotemporal models and economics to estimate the climate-related respiratory disease burden. In particular, I will use nationwide respiratory health data and daily spatially-resolved temperature to estimate the effect of extreme temperatures on respiratory health in the UK. I will also quantify the future burden of temperature-related respiratory health using Bayesian evidence synthesis methods, while propagating the different sources of uncertainty, such as future GHG emission scenarios. Lastly, I will develop a web application to communicate the resulting maps and costs to public health experts and stakeholders. The impact of the project is manifold: it provides a better understanding of the climate-related respiratory disease burden, proposes a methodology that can be extended to other drivers of global disease and pays particular attention to disseminating the results through user-friendly web-applications.

The rapid increase in the availability of high spatiotemporal resolution temperature projections and simultaneous advances in computational power both offer opportunities and pose challenges to epidemiological research in relation to climate change. Often overlooking the spatial dimension, most epidemiological studies have focused on the temporal component. The work I am proposing will provide a toolbox to explore both temporal and spatial dimensions of health risk in relation to climate change. Within this framework, investigators can derive maps of future risk projections which provide insights on the potential drivers of vulnerability. The proposed methodology, coupled with economic evaluations, will provide a comprehensive framework for estimating the financial and public health burden of climate-related diseases. This project will also be one of the first to provide nationwide estimates and maps of future temperature-related respiratory health impacts in the UK.
This work is a collaboration among the MRC Centre for Environment and Health, the National Health & Lung Institute, the MRC Centre for Global Infectious Disease Analysis, University College London (UCL), and the London School of Hygiene and Tropical Medicine, as well as involve ISGlobal in Barcelona and the Institute of Social and Preventive Medicine in Bern. The overall aim of the project-understanding spatiotemporal trends of respiratory health in relation to environmental exposures, and in particular climate change-is well suited to the multidisciplinary MRC Centre for Environment and Health. Its links with King's College London and Public Health England offer a unique opportunity to collaborate with public health scientists and translate the results into future adaptation strategies. The project also focuses on health economics, a research priority of Imperial College London, and it pays particular attention to communicating results either through peer-reviewed publications and scientific conferences or through Shiny apps of the statistical software R. All work will be also publicly available through either open access publishers or pre-prints. Finally, I will disseminate the methodological framework through online tutorials, courses, and R-code.
The applications of this framework go beyond temperature-related respiratory health. The framework can be extended to other drivers of global disease burdens such as vector-borne infections, HIV, neglected tropical diseases, and emerging infectious diseases in regions that are more vulnerable to climate change or extreme events such as wildfires and droughts.