One of the most notorious effects of the climate crisis is the increase in heat waves, both in frequency and intensity. Furthermore, extreme temperatures and mortality have a relationship that has been widely studied and analyzed by the scientific community.
SpainAlong with the rest of the countries of the Mediterranean basin, it is one of the territories where global warming will most affect; Therefore, it is possible to assume a future scenario of stronger and more frequent heat waves, with more deaths as a consequence of these if there is no planning to mitigate extreme temperatures.
In this sense it is expressed Cristina Linares placeholder image, Senior Scientist of the Department of Epidemiology and Biostatistics of the National School of Health, of the Carlos III Health Institute (ENS-ISCIII). The researcher is co-author of two recent publications that study the relationship between extreme heat episodes in our country and the impact on mortality in the population.
Energy poverty in Spain has always been associated with the economic inability of families to maintain an adequate temperature in their homes during the months of greatest consumption, which coincide with the coldest. The scientist considers, in conversation with SINC, that energy poverty linked to extreme heat is “an unexplored but potentially relevant facet” to carry out studies on which socioeconomic factors make some populations more vulnerable than others.
Madrid neighborhoods with lower income, more vulnerable to the heat
An investigation by Linares and Julio Diaz, head of the Department of Epidemiology and Biostatistics of the ENS-ISCIII, analyzes different factors that are associated with heat-related mortality in 17 districts of Madrid from 2010 to 2013: percentage of population over 65 years, hectares of green areas, income level and existence of air conditioners.
The results of the work detect that there are deaths linked to extreme heat in only three districts: Tetuán, Carabanchel and Puente de Vallecas. The only factor that explains this behavior is the income level, in line with previous studies that indicate that the population with the fewest resources is the one most at risk during heat waves.
“In Tetuán and Puente de Vallecas, the effect of heat is immediate: mortality occurs the same day that the threshold temperature is exceeded. In Carabanchel there is also a short-term effect, two days later, but without statistically significant differences,” he says Linares.
How does rent affect extreme heat mitigation? “It conditions the use of air conditioning systems in homes, and also [las familias] they have difficulties to face the repair and improvement of the house and can even determine the assistance and health of vulnerable people “, points out the researcher.
Although it seems that the level of family income is directly related to having or not having an air conditioner, these separate indicators can explain different realities. Linares points out that, “even if one is available, people with low incomes tend not to use them when they feel discomfort technical due to the inability to cope with its electricity consumption ”
Similarly, it indicates that families with lower income may not have the time and resources to guarantee care for the population at risk from heat. “On the other hand, families with higher incomes could be accessing services that offer additional protection, such as private health or assistance resources,” he indicates.
Public policies against heat
Although it is not the first study to analyze the impact of heat on populations with fewer resources, this work by the National School of Health is one of the few that addresses this problem in neighborhoods, taking into account the great socioeconomic, demographic and urban planning of a city like Madrid.
Knowing these variables and their impact on thermal acclimatization can be crucial to develop administrative actions that mitigate the consequences of extreme heat. “Public policies to increase urban park and forest areas, as well as green facades and roofs, have a wide margin for development in Madrid”, says Linares.
For the population with fewer resources, the ISCIII researcher specifies that the healthcare company and the air conditioning of homes “may imply great advances in the mitigation of mortality associated with heat waves.”
Madrid and Seville, increasingly used to the heat
The minimum temperature necessary for heat to have an impact on mortality in the provinces of Madrid and Seville is increasingly higher, according to the study by Cristina Linares and Julio Díaz that analyzes how this 1983 Minimum Mortality Temperature (MMT) has varied to 2018.
The work concludes that this MMR has increased at a rate of 0.57ºC per decade in the country’s capital, while in Seville it has been 1.12ºC per decade. Julio Díaz explains that these indicators may reflect that there are “economic improvements with greater access to air conditioning” and the existence of heat prevention plans aimed at vulnerable groups.
The MMR, as detailed by Cristina Linares, is a specific indicator for each city that represents the mortality behavior of a population in a specific climate zone. Thus, Madrid is a good example of a province when evaluating the influence of heat waves “as it represents the behavior of a large city”, while Seville is one of the capitals of the country’s provinces most affected by heat extreme.
Another piece of data observed in this study is that there is a higher MMR in men than in women, “which would indicate a greater vulnerability to the impact of heat in women,” the researcher indicates.
“There are physiological differences in the thermoregulatory function between the sexes that can explain this greater impact: body size, physical condition, habitual medication and acclimatization state,” he answers. To this is added the role that sex hormones have in thermoregulatory mechanisms and that one of the key age groups to study the effects of heat are elderly women – with a longer life expectancy than men – who live alone and in bad socioeconomic conditions that do not allow a good acclimatization of the house.