In particular, during the last two decades, rainfall has increased in frequency and intensity, becoming extreme and in some particular geographical areas have become more abundant flooding. In the United States today, for example, flooding is the second most common cause of death (an average of 98 deaths per year due to drowning) among all climate change incidents and hazards and tropical storms causing the most deaths.

The number of deaths caused by flooding usually increases even in the weeks following the flood because there are many outbreaks of infectious diseases transmitted by water (diarrhoea, cholera, typhoid). In addition, houses and buildings affected by floods and hurricanes, subject to such heavy water infiltration, almost always cause mould contamination that degrades indoor air quality: this is why asthma and other severe upper respiratory tract symptoms (especially wheezing and coughing), as well as other lower respiratory tract symptoms (pneumonia), affect people who continue to live or are forced to live in such environments.

What has just been described concerns the problems caused by floods and inundation but, of course, there are also those caused by the opposite extreme events, like droughts, that put public health and safety at risk. Dust storms, extreme heat and fires can contribute to a significant degradation of air quality by producing so-called ‘particulate matter’, a mixture of solid and/or liquid substances of nanometric dimensions that are particularly insidious to the lungs and respiratory tract, almost always present in densely populated urban areas: in addition, excessive temperatures are very often the cause of cardiovascular problems (fainting spells and heart attacks).