A new study has found a relationship between ambient air pollution and the mental health of those living in the United Kingdom. The findings indicate that when individuals are exposed to air pollution, even below the standards for air quality in the United Kingdom, they are more likely to suffer from anxiety and depression.
The study, which was published in JAMA Psychiatry, offers insight into the potential consequences of long-term air pollution.
Mental disorders are a growing cause of disability. Public health priorities include identifying modifiable risk factors of anxiety and depression and developing prevention interventions. A growing body of research is linking ambient air pollutants to mental disorders. Multiple studies have found that exposure to air pollutants for a short time is linked with increased depression and anxiety.
Evidence of long-term impacts is contradictory, and few studies have examined the effects of air pollutants on depression and anxiety. Previous studies focused on air pollutants individually, despite ambient pollution consisting of particulate matter (PM) and gaseous pollutants.
In order to assess the consequences of long-term exposure to air pollutants, Teng Yang and colleagues used data from the UK Biobank (a large population database) to investigate the relationship between pollution exposure and anxiety or depression. Their sample included 389,185 individuals who provided data over ten years.
Information on lifestyles, sociodemographic characteristics, and health data was collected. Participants were confirmed as having anxiety or depression through self-reporting, inpatient hospital records, primary care, and death records. These codes are part of the International Statistical Classification of Diseases and Related Health Problems (ICD-10). They also collected race and ethnicity information.
Yang and colleagues found that exposure to air pollutants for varying periods and exposure to air pollutants in combination were associated with increased risks of incident anxiety and depression. These findings could fill in the gaps in associations between air pollutants and mental health for air pollution levels below UK air quality standards.
Statistical analysis of the data suggests that incident anxiety and depression are more likely to occur at lower levels of air pollution and then plateau at higher levels. This has important implications for air pollution control policy.
Previous studies found associations between hospitalizations or outpatient visits due to depression and anxiety and short-term exposure to air pollution. However, few longitudinal studies investigated the relationship between long-term exposure to air pollution and depression or anxiety. Previous studies have also been carried out in areas where air pollution levels exceeded the UK standards for air quality.
The research team found positive correlations consistent with two single-city studies conducted in Korea and China. This was also the first prospective study that reported a significant increase in the risk of depression and anxiety associated with the air quality score, which reflects exposure to multiple pollutants. Even at levels of air pollution below UK standards for annual concentrations, the study found an increased risk of depression and anxiety.
The study has some limitations, including the absence of information about some air pollutants, potential selection bias within the UK Biobank, and possible underestimation due to undiagnosed disorders. Despite these concerns, the study’s results suggest that efforts to reduce pollution could positively impact mental health.
Yang and colleagues conclude that air pollution regulations and standards must be tightened and that reducing exposure to air pollutants could reduce the burden of mental illnesses such as depression and anxiety. It is necessary to conduct further research to understand the mechanisms behind the link between air pollution, mental health, and anxiety. Subgroup analyses revealed that gender might modulate susceptibility to anxiety in relation to PM2.5 exposure. It is still necessary to explore the role estrogen fluctuations in females may play in these associations.
The study, “Long-term exposure to multiple ambient air pollutants and association with incident depression and anxiety,” was authored by Teng Yang, Jiawei Wang, Jing Huang, Frank J. Kelly, and Guoxing Li.