Short-term effects of traffic noise on suicides and emergency hospital admissions due to anxiety and depression in Madrid (Spain)

Studies show a relationship between some mental illnesses and suicides and different environmental variables such as air pollution, characterized by stress at the neuropsychological level. Despite the fact that traffic noise is also a powerful neurological stressor, studies that relate traffic noise to these mental disorders are practically non-existent. The objective is to analyze the short-term impact that chemical air pollution, traffic noise and thermal extremes have on emergency hospital admissions due to anxiety, dementia and suicides in the city of Madrid. This ecological, longitudinal study uses generalized linear models with Poisson link to analyze the short-term impact of the average daily concentrations of chemical pollutants (NO2, PM10, PM2.5, O3), noise pollution indicators (Leqday, Leqnight and Leq24h) and temperatures during heat waves (Theat) and cold waves (Tcold) on daily admissions to emergency services in the city of Madrid from 2010 to 2013 due to anxiety (ICD-10: F32), depression (ICD-10: F40-F42) and suicide (ICD-10: X60-X84). The results show no association between any of the chemical pollutants considered and the dependent variables studied. On the contrary, the values of Leqday are associated with the three variables analyzed in lag 0 for the cases of anxiety and depression and in lag 1 for suicides, with RR: 1.20 (IC95% 1.14 1.26), RR: 1.11 (IC95% 1.06 1.16) and RR: 1.17 (IC95% 1.05 1.30), respectively, for increases of 1 dB(A) in the values of Leqday. An association was also found between Tcold and admissions for anxiety in lag 9 with RR: 1.62 (IC95% 1.18 2.22) for increases of 1 °C in the values of Tcold. Traffic noise can be considered an important risk factor related to the illnesses and anxiety and depression and for suicides in the city of Madrid, although new studies are needed to support the findings shown here.