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Il legame tra inquinamento e suicidi: quando la cura dell’ambiente e la salute mentale vanno insieme

It may seem exaggerated or, for some deniers, yet another attempt at "state psychological terrorism", but among the negative consequences of pollution there is also an increase in the suicide rate. A scientific article published in the prestigious journal pnas talks about it, which demonstrates how exposure to air pollution has negative consequences on mental health.

According to previous studies, this can happen both directly, through brain inflammation and oxidative stress, and indirectly, through economic or other physical difficulties. To date, the existence of a positive relationship between air pollution and mental health problems, including anxiety, depression and suicide, has been demonstrated. The authors of this study, however, take a step forward and focus on the identification of a large-scale causal link between pollution exposure and suicide rates, in a context, that of the United States, which has long been experiencing a real Suicide rates in the United States have increased by approximately 30% over the past two decades, placing suicide as the fourth leading cause of years of life potentially lost before age 65 in 2020. .

In more detail, the article analyzes how air pollution caused by smoke from wildfires affects the risk of suicide in the United States. Wildfires are a significant source of air pollution, accounting for approximately 20% of microparticulate emissions in the United States. Furthermore, they will be more frequent and severe in the coming decades due to climate change and continued human development in previously pristine areas. The use of data relating to these fires is also justified by the fact that the columns of smoke from forest fires are precisely monitored by satellite sensors, which capture the position and thickness of these columns in all (large) areas of the United States.

The authors are able to combine measurements of smoke columns with data on all suicide deaths in the United States and produce a more nationally representative and precise estimate of the relationship between pollution and suicide than previous studies, also observing how this relationship differs between rural and urban regions and between different socio-demographic groups.

The results show first of all that there is a positive relationship between exposure to smoke and air quality, especially in rural areas: an additional day of exposure to smoke increases the average concentrations of pm2.5 in the month of exposure by 0.41 μg /m3 in rural areas and 0.33 μg/m3 in urban urban contexts. The other relevant result is the presence of a causal and positive relationship between days of exposure to smoking and suicide rates. In rural areas, an additional day of exposure tends to increase suicides by 0.11 deaths per million population. The effect is driven by rural areas, while in urban contexts the authors estimate an almost zero effect.

Looking at estimates of the effects of smoking on suicide rates by population subgroups (defined by gender, age, ethnicity and education), impacts in rural areas are concentrated among men, working-age adults, non-Hispanic whites and adults without a college education. These groups, among other things, already have particularly high risks of suicide: these are groups for which an alarming incidence of so-called "deaths of despair" has been estimated in the United States.

Finally, based on these findings, the authors calculate that, in rural areas, a 1 μg/m3 (13%) increase in monthly PM2.5 concentrations derived from forest fires leads to 0.27 additional suicide deaths per million. of inhabitants (i.e. an increase of 2.0%).

This study provides empirically robust, large-scale evidence of an additional consequence of pollution: exposure to poor air quality increases the propensity to commit suicide, with a greater impact among rural populations and those groups who are already high risk.

An additional motivation, therefore, to adopt policies and behaviors that increase the environmental sustainability of our activities: the protection of the human species cannot ignore the protection of the environment.

The authors of the study focus on identifying a large-scale causal link between pollution exposure and suicide rates, in a context, that of the United States, which has long been experiencing a true "national mental health crisis" In fact, suicide rates in the United States have increased by approximately 30% over the past two decades

Pierluigi Conzo

NP Ottobre 2023