Respiratory diseases, pulmonologists: "Don't underestimate night heat waves"

When we think about the impact that heat has, especially on respiratory health, we naturally tend to worry about the hottest hours of the day, with the sun beating down on our heads and the mercury column that, as in these days, shoots up to impressive values.

In fact, one of the aspects of heat waves that has a very serious impact on respiratory diseases is the one linked to high night temperatures , which are often underestimated, despite causing respiratory symptoms to worsen during the night. Warning about the increased risks to lung health when the heat remains intense even at night is Giovanna Elisiana Carpagnano, Full Professor and Director of Pneumology at the Policlinico di Bari, during the international meeting on respiratory diseases, co-organized by the Menarini Foundation, in collaboration with the University of Bari "Aldo Moro" and the University of Foggia, which saw the participation of pulmonologists and specialists from all over the world. "We know that the consequences of heat waves are particularly dangerous for the respiratory system, as it is the primary target organ of climate change and environmental degradation. What is less known, however, is that nighttime minimum temperatures are rising even more rapidly than daytime maximums and that "tropical" nights, with minimums of up to 25°C , have a serious impact on respiratory health , equal to that of daytime heat waves," underlines Carpagnano.

In fact, due to the climate crisis, our country, according to data from the European Environment Agency, is ranked third in Europe for the number of annual tropical nights, behind only Greece and Cyprus. Already in the thirty-year period 1981-2010, Italy had reached an average of 41.6 nights per year above 20°C. This figure has been increasing over the years, especially in cities, where the "heat island" effect amplifies the problem. "In recent summers, in fact, we have reached 48 "hot" nights, equal to 52% of the season, of which 13 nights with temperatures above 23°C, with a toll on health and victims that is often disconcerting", Carpagnano points out. This was revealed by a study published in Environmental Health Perspectives, which took into consideration data on daily minimum and maximum temperatures recorded in Japan, with latitudes similar to those of our country, over a period of over 40 years, from 1973 to 2015. According to the research, nighttime heat waves, with minimum temperatures of up to 25°C, would in fact increase the mortality rate for respiratory diseases by 10%, regardless of the daytime temperature .

"This is due to the fact that the night is, in itself, a critical element , because during rest, the caliber of the bronchi, even in healthy individuals, reduces by up to 8% . This narrowing of the airways , linked to the circadian rhythm, is aggravated in those who suffer from asthma by the extreme heat at night which , causing an increase in temperature inside the chest, activates the nerve fibers of the respiratory muscles , which, by not relaxing, do not allow normal lung emptying, making breathing difficult, with very serious asthmatic attacks that can even be fatal", explains the expert. "It is therefore important to encourage the most vulnerable subjects to take precautions such as the use of fans or dehumidifiers during the night, especially when it comes to the elderly and asthmatic children. These patients must try to create, inside their home, especially in the bedroom, a cool environment to reduce the impact of night-time heat waves and minimize possible discomfort and damage to health", concludes Carpagnano.