Hot nights are related to greater risk of death

An international study has confirmed that hot nights They relate to a Mortality increase up to three percent and that night heat has an independent effect of high daytime temperatures, so it requires specific prevention measures.

This has been revealed by a research team formed by more than 40 institutions from different countries, including Spain, represented by the Higher Council for Scientific Research (CSIC) Through the Biological Mission of Galicia (MBG), the Institute of Environmental Diagnosis and Water Studies (Idaea, Catalonia) and the Doñana Biological Station (EBD, Andalusia); and the University of Valencia.

The work, published in ‘Environmental International‘, has analyzed more than 14 million deaths in 178 cities from 44 countries in the period between 1990 and 2018, using two thermal indices, excess of hot night and duration of this; and advanced statistical models. The cities were selected based on the availability of data, being represented by Spain 42 provincial capitals.

The results have shown that hot nights contribute to the risk of mortality related to high temperatures in all climates And regions, except in northern Europe, where the association has been only suggestive.

“Night heat prevents the physiological recovery of the body after daytime thermal stress, affects sleep quality and can aggravate cardiovascular, respiratory and neurological diseases. In cities with urban heat island effect, night exposure can be even more intense,” said researcher Ramón and Cajal in the Dominic Royé MBG, first author of the study.

The scientist has signed up for the special vulnerability of cities such as Madrid, Valencia, Barcelona and Sevillewhich have a high frequency of tropical and equatorial nights. It has also affected the greatest risk for the elderly, chronic patients and those living in cities with low ventilation or limited access to air conditioning.

Preventive measures

After confirming the relationship between hot nights and the risk of mortality, the research team has advocated to include night heat in early alert systems, develop urban climatic shelters and increase green areas, guarantee adequate thermal conditions in homes, hospitals and residences and design prevention plans that consider night heat as a specific risk.

“Tropical nights have increased substantially in recent years due to climate change. This summer we have seen it unpublished, and the situation intensifies, increasing the risk for the most vulnerable people,” said the investigator of the IDAEA-CSIC, Aurelio Tobíasauthor of the study.

However, researchers have pointed out that more studies are necessary to analyze the relationship between the effects of diurnal and nocturnal heat in cities of other climates and examine vulnerable subgroups. In addition, they have pointed out that it is unknown how excess heat and duration relate; For example, if short periods of very high temperatures are more harmful or that they extend over time.