Does air pollution trigger suicide? A case-crossover analysis of suicide deaths over the life span

The role of seasonality and photoperiod on the lethality of suicide attempts: A case-control study

BACKGROUND

The risk factors related to suicidal behaviors are complex and not yet fully known. Several studies underline how suicide results from the combination of psycho-social, biological, cultural, and environmental factors. The aim of this study was to investigate the potential role of seasonality and photoperiod on high-lethality suicide attempts (HLSA) compared with low-lethality suicide attempts (LLSA) in a sample of psychiatric inpatients.

METHODS

After attempting suicide, subjects were admitted in the emergency/psychiatric ward of the IRCCS Ospedale Policlinico San Martino from 1st August 2013 to 31st July 2018. Socio-demographic and clinical characteristics were collected.

RESULTS

The sample consisted of four hundred thirty-two individuals admitted for suicide attempt. One hundred thirty-three subjects (30.8%) of the sample committed a HLSA. The HLSA group peaked in the months with a higher sunlight exposure (June and July). Bivariate correlation analyses between seasonality/photoperiod in the whole sample and HLSA were positively associated with summer and highest solar intensity period.

LIMITATIONS

Data were limited to a single hospital, patients' seasonal environment, meteorological variables and psychological factors. In addition, the presence of acute life-events fostering the suicidal crisis has not been investigated.

CONCLUSIONS

The current study provides a novel perspective on the questions surrounding the impact of seasonality and daylight exposure on lethality of suicide attempts. further studies are needed to provide deeper understandings on the delicate molecular network that links suicide behaviors, seasonality and daylight in order to develop more effective prevention and treatment strategies in the future.

Air pollution associated with non-suicidal self-injury in Chinese adolescent students: A cross-sectional study

BACKGROUND

Non-suicidal self-injury (NSSI) is a frequent phenomenon in adolescents and is closely related to eventual suicide. Although the effect of air pollution on various diseases has been extensively investigated, no studies examined its effect on NSSI in young students.

OBJECTIVES

We investigated the effect of air pollution on NSSI in Chinese students.

METHODS

We investigated the incidence of NSSI in the past 12 months in 54 923 Chinese students with an anonymous questionnaire. We assessed the air pollution exposure of each student by the air quality matched with their schools, which were calculated by the inverse distance weighting method from the environmental monitoring data. We discussed the association between ambient air pollutants and the incidence of NSSI using generalized additive mixed models.

RESULTS

A 10 μg/m³ increase in the annual moving average concentration of particulate matter with diameters less than 2.5 μm (PM_2.5) and ozone (O₃) was associated with a 13.9 percent and a 10.5 percent increase in the odds ratio (OR) of NSSI, respectively. In addition, a 0.1 mg/m³ increase in the annual moving average concentration of carbon monoxide (CO) was associated with a 4.8 percent increase in the OR of NSSI. NO₂ and SO₂ were not related to NSSI. CO and O₃ show non-linear effects on NSSI. Male students in high school are the most s to the effects of PM_2.5 on NSSI.

CONCLUSIONS

Our study suggests that increases in PM_2.5, O₃ and CO may increase the incidence of NSSI among adolescent students.

Is there a link between air pollution and mental disorders?

Several studies have demonstrated the association between air pollution and different medical conditions including respiratory and cardiovascular diseases. Air pollutants might have a role also in the etiology of mental disorders in the light of their toxicity on central nervous system. Purpose of the present manuscript was to review and summarize available data about an association between psychiatric disorders and air pollution. A research in the main database sources has been conducted to identify relevant papers about the topic. Different air pollutants and in particular PM and nitric oxides have been associated with poor mental health; long exposition to PM_2.5 has been associated with an increased risk of new onset of depressive symptoms (Cohen's effect size d: 0.05-0.81), while increased concentration of nitric dioxide in summer with worsening of existing depressive conditions (Cohen's effect size d: 0.05-1.77). However, the interpretation of these finding should take into account the retrospective design of most of studies, different periods of observations, confounding factors such as advanced age or medical comorbidity. Further studies with rigorous methodology are needed to confirm the results of available literature about this topic.

Ambient ozone exposure and mental health: A systematic review of epidemiological studies

BACKGROUND

An increasing number of studies have suggested adverse effects of air pollution on mental health. Given the potentially negative impacts of ozone exposure on the immune and nervous system driven from animal experiments, ozone might also affect mental health. However, no systematic synthesis of the relevant literature has been conducted yet. This paper reviews the studies that assessed the link between ozone exposure and mental health thus far.

METHODS

We followed the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA). PubMed, Web of Science, and EMBASE were systematically searched for epidemiological studies on ambient ozone exposure and mental or behavioral disorders according to the International Classification of Disease. The period was from January 1st, 1960 to December 14st, 2017. We evaluated the risk of bias by the Office of Health Assessment and Translation (OHAT) Approach and Navigation Guide for each included study.

RESULTS

The keyword search yielded 567 results. 31 papers met the selection criteria and were included in the review. We found only inconclusive evidence that ozone affects autism spectrum disorders, impairment of cognitive functions and dementia, depression, and suicide. The large heterogeneity of study designs, outcome definitions and study quality in general prevented us from conducting meta-analyses.

CONCLUSIONS

Current evidence for an association between ambient ozone exposure and mental health outcomes is inconclusive and further high quality studies are needed to assess any potential links given the strong biologic plausibility.

Ambient air pollution exposure and emergency department visits for substance abuse

There is growing evidence supporting the notion that exposure to air pollution can contribute to cognitive and psychiatric disorders, including depression and suicide. Given the relationship between exposure to acute stressors and substance abuse, the present study assessed the association between exposure to ambient air pollution and emergency department (ED) visits for alcohol and drug abuse. ED visit data selected according to International Classification of Disease (ICD-9) coding 303 (alcohol dependence syndromes) and 305 (non-dependent abuse of drugs) were collected in five hospitals in Edmonton, Canada. A time-stratified case crossover design was used. Conditional logistic regression was applied to calculate odds ratios (OR) and 95% confidence intervals (95% CI). Season, temperature, and relative humidity were adjusted for using natural splines.

Results are reported for an increase in pollutant concentrations equivalent to one interquartile range (IQR). Statistically significant positive associations with substance abuse were observed for CO, NO₂ and particulate matter with an aerodynamic diameter less than 10 μm (PM₁₀) and 2.5 μm (PM_2.5). The strongest results were obtained in the cold period (October–March) for 1-day lagged CO (OR = 1.03, 95% CI: 1.01, 1.05, IQR = 0.4 ppm) and NO₂ (OR = 1.04, 95% CI: 1.01, 1.07, IQR = 12.8 ppb); ORs were also significant for CO and NO₂ with lags of 2 to 6 days and 2 to 7 days, respectively. The study suggests that, even at low levels, increases in ambient CO, NO₂, and PMs are associated with increased hospital admissions for substance abuse, possibly as a result of impacts of air quality on mental health or depression.

The association between daily concentrations of air pollution and visits to a psychiatric emergency unit: a case-crossover study

BACKGROUND

Air pollution is one of the leading causes of mortality and morbidity worldwide. Experimental studies, and a few epidemiological studies, suggest that air pollution may cause acute exacerbation of psychiatric disorders, and even increase the rate of suicide attempts, but epidemiological studies on air pollution in association with psychiatric disorders are still few. Our aim was to investigate associations between daily fluctuations in air pollution concentrations and the daily number of visits to a psychiatric emergency unit.

METHODS

Data from Sahlgrenska University Hospital, Gothenburg, Sweden, on the daily number of visits to the Psychiatric emergency unit were combined with daily data on monitored concentrations of respirable particulate matter(PM₁₀), ozone(O₃), nitrogen dioxides(NO₂) and temperature between 1st July 2012 and 31st December 2016. We used a case-crossover design to analyze data with conditional Poisson regression models allowing for over-dispersion. We stratified data on season.

RESULTS

Visits increased with increasing PM₁₀ levels during the warmer season (April to September) in both single-pollutant and two-pollutant models. For example, an increase of 3.6% (95% Confidence Interval, CI, 0.4-7.0%) was observed with a 10 μg/m3 increase in PM₁₀ adjusted for NO₂. In the three-pollutant models (adjusting for NO₂ and O₃ simultaneously) the increase was 3.3% (95% CI, -0.2-6.9). There were no clear associations between the outcome and NO₂, O₃, or PM₁₀ during the colder season (October to March).

CONCLUSIONS

Ambient air particle concentrations were associated with the number of visits to the Psychiatric emergency unit in the warm season. The results were only borderline statistically significant in the fully adjusted (three-pollutant) models in this small study. The observation could be interpreted as indicative of air pollution as either exacerbating an underlying psychiatric disorder, or increasing mental distress, even in areas with comparatively low levels of air pollution. In combination with the severe impact of psychiatric disorders and mental distress on society and individuals, our results are a strong warrant for future research in this area.