It was precisely Public Health that justified Liliane Morais' Ph.D. thesis on the subject Morbi-Mortality Associated with Excessive Heat Periods: Contribution to a Local Strategy for Public Health Promotion.
As part of the 1st edition of Doctoral Degrees of the Environmental Health Institute (ISAMB) of the Faculty of Medicine, the idea of studying heat waves came from the days of the Master Degree, when she studied the subject, albeit in a different way. Over time, Liliane realized that the various projections continued to indicate “an increase in the frequency, intensity and duration of these heat waves”. The truth is that "as these are already considered one of the most important climate risks and one of the main causes of mortality in the world, the existence of more data and more detail" on them led to a renewed interest in the subject, deepening it to obtain other kind of answers. The choice of the institution was therefore no less logical than the choice of topic. Understanding the answers about Public Health does not only imply studying medicine, but also all other sciences and their perspectives, in the quest to understand how to improve the health and lives of populations. "It is about elevating the concept of health from a multidisciplinary, translational perspective, recognizing that a set of complex relationships contribute to our health, with different factors: physical, biological, environmental, socioeconomic, and urban (built environment)", she explained.
In the conversation with Liliane Morais, it was clear that mortality from cardiorespiratory disease and in situations of extreme heat, analysed between the months of May and September, was more evident. But it was also evident that big cities like Lisbon interfere with the physical health of their populations. It is in this sense that talking about health implies not only the physical concept, but also the environmental one. The dichotomy between the green environment and the one that is built gave her new answers. In green areas, the cardiorespiratory component improves, as there is greater dispersion of pollutants and a decrease in temperature, since the air circulates more. On the contrary, large urban spaces whose green area is smaller, aggravate the concentration of extreme heat, due to several factors, consequently contributing to the formation of high concentrations of ozone.
“Politicians therefore cannot run away from it for much longer”, she said calmly, explaining the evidence mirrored in the two published papers. Talking about cities designed in an emotional way is to impose on them characteristics that are ever closer to the green reality, with a more harmonious performance between human intervention and that of nature.
Environmental evidence shows us that if nothing is done by 2050, the economy will have the enormous challenge of dealing with heat waves that will have great health costs, as they make their populations more exposed to these waves, thus vulnerable. Still with some significant differences between cities, they are the ones that concentrate heat the most and cause the greatest damage to the health of populations over 65 years of age. Other factors, such as access to medical care and socioeconomic status, also affect the final conclusions regarding cardiovascular and respiratory diseases, which can lead to death.
Liliane Morais wrote her doctoral thesis to deepen the analysis of heat waves, examining the EHF (Excess Heat Factor) and the GATO (Generalized Accumulated Thermal Overload - Icarus index), as well as to understand and map the interaction of cardiorespiratory mortality associated with heat in the elderly with multiple analysis factors (environmental, urban, socioeconomic, and access to primary health care).
What justifies an ever-increasing increase in heat waves and to what extent do they affect human health?
Liliane Morais: Several researchers and multiple reports, by different institutions, show that climate change due to the influence of human activity has contributed to the increase in extreme weather events, such as heat waves – which are predicted not only to be more frequent, but also more intense and lasting. Several measures have been taken by different countries (some more than others) to limit global warming below 2°C and there are several efforts to limit the increase in temperature above 1.5°C. However, in recent decades, Europe has registered an increase in the number of heat waves, as well as a significant increase in the number of tropical nights (minimum temperature ≥ 20ºC) and extremely hot days (maximum temperature ≥ 35ºC).
The impact of heat waves on human health is enormous and is associated with several complex relationships, which translate into increased morbidity and mortality. I have already mentioned that heat waves are one of the main causes of mortality around the world, which, taken together with climate warming, shows that this issue needs to be addressed seriously. To get a sense of the data, let me give you the classic example of the 2003 European heat wave, responsible for about 70,000 heat-related deaths. At the same time, there is also an increase in the number of hospitalizations, as the heat aggravates some chronic pathologies, especially cardiovascular and respiratory diseases, but also kidney diseases, diabetes, and mental health disorders, among others. Naturally, the elderly are the most vulnerable group, as ageing impairs the body's physiological ability to regulate its temperature. Finally, I end with the direct effects of extreme heat that can result in a succession of illnesses such as cramps, syncope, heat exhaustion or even heat stroke.
Following what you have just said, which conclusions do you draw that impact our Public Health?
Liliane Morais: From the various goals achieved, we can summarize the following aspects:
i) There is currently no need to update the ICARO Index (which carries out surveillance and monitoring of heat waves with potential effects on human health).
A comparison was made with another index to measure heat waves, the Excess Heat Factor (EHF), in order to find out which has the greatest predictive power for potentially preventable heat-related mortality. From the various analyses conducted based on daily mortality and air temperatures from 1980 to 2016 in Lisbon with the two indices, it was concluded that both were statistically significant for the total mortality group (all ages and all causes). For daily mortality in individuals aged ≥65 years and with all diseases of the circulatory and respiratory system, the ICARUS Index was the only index that significantly predicted the impact of heat waves on mortality, appearing to have the best statistical properties.
ii) Geographic scales reveal different degrees of detail in the analysis of health outcomes. The neighbourhood scale (statistical section) revealed different patterns of cardiorespiratory mortality compared with the usually available scale, the parish. The results suggest the relevance of analysing health outcomes on a more precise scale to better address the challenges of the health sector and improve support in planning decision-making, responding closely to the needs of citizens. It is possible to achieve better health management, optimize the allocation of resources, as well as improve policy formulation, which is more detailed and conscientious, allowing for greater climate-health equity in the promotion of cities.
iii) Through hot spot analysis, the spatial pattern of heat-related cardiorespiratory mortality in the elderly was identified at the neighbourhood scale. After realizing where, we will understand why. This means that the potential associations between spatial variability in heat-related mortality and several independent factors in each neighbourhood were studied. It can be said that the spatial model explains about 60% of the spatial variations in cardiorespiratory heat mortality in the elderly. The main predictive variables are the elderly (the demographic factor is very important), green areas (due to the immense benefits, namely in the contribution of lower temperature) and employment (a decisive factor for having greater purchasing power and better coping with excessive heat) .
In your final report you mentioned that Europe will be the one to suffer the biggest increase in temperatures. Why?
Liliane Morais: Yes, it's true. Due to its geographical position, all projections show that Europe, especially southern Europe and the Iberian Peninsula, will be an area particularly sensitive to temperature increase, whose warming will be greater than the predicted global average increase. In fact, this is already evident, and as I have also mentioned, in recent decades there has been an increase in the number of heat waves, tropical nights and extremely hot days in Europe. If we mention the numbers (I like to refer to numbers because they give us a more accurate idea of the extent of the phenomenon), if there are no adaptation and acclimatization measures, heat-related mortality in Europe, especially in the South, would increase between 60,000 and 165,000 deaths per year in the 2080s compared to the current baseline. I have not yet mentioned the economic repercussions, but heat waves in the European Union are estimated to cost €150 billion by 2050.
You claim that there is no global quantitative definition that can assess heat waves across the board, with each country having its own analysis. What is the reason?
Liliane Morais: In fact, there is no universal quantitative definition of a heat wave. There are some proposals, but there is no clear quantitative definition. Due to their characteristics and impacts, heat waves vary a lot. The challenges in modelling the temperature/health relationship are enormous. For example, the response from the population is heterogeneous due to acclimatization, different degrees of adaptation and different vulnerability factors. Thus, heat waves correspond to the climate of a location, so certain weather conditions can create a heat wave in one place but not in another. There will hardly be equal heat waves in terms of spatial extension, duration and intensity, as they can vary substantially within a region. Nevertheless, in the context of health, we can say that heat waves are events that are essentially related to a combination of extremely high daytime and nigh time temperatures, with high relative humidity and often with a prolonged duration (several days, but at least two days) of extreme heat. These events also contribute to increased morbidity, mortality and the increase in the number of cases of emergency services.
Does the phenomenon of heat waves allow us to say that there is a concept of seasonal mortality?
Liliane Morais: Yes, no doubt. Likewise, there is also seasonal mortality related to cold waves. However, there is an extension of the summer season, so that heat-related mortality is expected to occur more and more in months that are not considered hot, which has even greater repercussions on human health due to the “surprise” effect.
The desire of people who dream of leaving the city and going to quieter and greener places is not just psychological, is it? There are scientific foundations.
Liliane Morais: Yes, there are scientific grounds regarding the effect that green spaces have on human health. Not only do I speak for my study, which demonstrated the relevance of urban green spaces in understanding heat-related mortality, but there are many studies that mention the beneficial effect of green spaces on physical and mental health. It can be argued that urban green spaces can effectively reduce environmental health risks. Access to green spaces is associated with an improvement in air quality, carbon “capture”, a contribution to limiting temperature and reducing noise levels, for example. I would say that the more extensive the green spaces and the larger trees they have, the more expressive the benefits for the human health of the citizens who visit them.
The first time we talked and you explained your thesis, you said something like, "these studies show that politicians cannot run away from it for much longer". Do you care to comment? How can we predict heat adaptability and thus avoid premature death?
Liliane Morais: Dominating or controlling climate change is not just about the individual. It requires a response that involves players from different areas, who have a single strategy to deal with the consequences of climate change, ensuring coordination and synergies. In this sense, there must be a political commitment, both nationally and locally, to ensure greater equity in terms of public health in cities. At the planning level, urban planners have to be aware of the current climate and future projections, finding a balance between existing buildings and those that are designed (and if effectively necessary). We need to think about current needs and anticipate future needs, always thinking in a holistic perspective. However, mitigation and adaptation measures to be planned and effectively implemented require a “strong” governance that no longer creates cities driven by socioeconomic parameters often disconnected from the real needs of citizens and cities. Planning needs to be directed towards reducing vulnerability to a minimum, increasing the resilience of cities, ensuring that policies are socially inclusive and progress towards the transition to low carbon. Everything is easier and faster if political commitment plays a central role. Still, let me say that progress is being made. Politicians are increasingly aware of the importance of climate change, but we can always do more and commit even more to the future. Take the COP26 as an example, which was a little short of expectations.
It is important that the knowledge generated in the academy is able to leave the the academy and reach society, and that companies/institutions will be able to take advantage of the results and act with greater awareness/compliance. This added value that is attributed to the knowledge generated is, without a doubt, something very interesting.