How the Vulnerable Are Disproportionately Affected By Air Pollution

Air pollution, impacting over 90% of the global population, is increasingly linked to mental health issues, particularly stress, anxiety, and depression. Vulnerable groups – pregnant women, children, the elderly, and those of lower socioeconomic status – are disproportionately affected. This evidence highlights the urgent need for public health strategies that address both environmental and mental health, particularly for those most at risk.

—

Air pollution is a significant factor affecting physical and mental health, affecting over over 90% of the global population and responsible for millions of annual premature deaths. Air pollution has been long associated with respiratory and cardiovascular diseases. Emerging research shows strong links between exposure to air pollutants and the development or exacerbation of mental health disorders, including anxiety, depression, and cognitive decline. These mental health impacts are particularly concerning as they contribute to a broad range of adverse outcomes, from decreased quality of life to increased mortality rates.

Mental health disorders are one of the most critical public health challenges around the world.  They are a fast-growing cause of morbidity and a leading cause of disability, especially among young people. 

Depression, characterized by a low mood, including irritation or loss of pleasure or interest in activities for long periods, is one of the most common and severe mental disorders, affecting 5% of adults globally. It is often associated with physical changes such as tiredness, weight loss, and loss of appetite, accompanied by cognitive changes that significantly affect the individual’s capacity to function. Anxiety is a feeling of unease, such as worry, irritability and fear or dread, that is activated when we are feeling threatened, under pressure or stressed. Anxiety is normal and affects everyone at some stage in life, though it can range from mild to severe, often leading to serious anxiety disorders. Various anxiety disorders can range from a generalized anxiety disorder (the feeling of anxiousness or worry most of the time) to panic disorder (having regular panic attacks, often for no reason) to post-traumatic stress disorder (PTSD) or obsessive-compulsive disorder (OCD). Similarly to depression, anxiety disorders are also most of the common mental health problems, with up to 301 million people, or 4% of the global population, experiencing symptoms regularly. 

Vulnerable populations are disproportionately affected by these mental health consequences. Pregnant women face increased risks of anxiety and depression, with air pollution potentially exacerbating these conditions and leading to severe postpartum complications and adverse fetal outcomes. The elderly are also at heightened risk due to age-related health declines, with air pollution accelerating cognitive decline and contributing to anxiety and depression. Individuals with pre-existing health conditions and from lower socioeconomic backgrounds are particularly susceptible, as air pollution can worsen their physical ailments while simultaneously heightening psychological stress. Children, with their developing bodies and minds, are especially vulnerable to pollution’s long-term cognitive and emotional effects.

Understanding these relationships is crucial for developing effective public health strategies to mitigate the mental health impacts of environmental pollution.

Pregnancy and Maternal Health

Exposure to air pollutants can increase mental health disorders during pregnancy, especially anxiety and depression. Depression affects around 10% of pregnant women around the globe, and anxiety, especially during the second trimester, is one of the most common psychiatric disorders during pregnancy and postpartum. To this day, it is still unknown why some women are more at risk of developing these disorders while others are more resilient despite the calamities. 

Depression and anxiety are associated with adverse results for maternal prenatal and postpartum depression, anhedonia, and suicide (accounting for 5-20% of postpartum deaths worldwide), as well as risk for the foetus, including premature birth and mortality, low birth weight, intrauterine growth restriction, subsequently developmental and neurodevelopment outcomes in infants, however, maternal anxiety and preterm birth findings, are less consistent compared to depression. Additionally, air pollution is also significantly linked to emotional stress during pregnancy, including acute stress. 

Women generally are more likely to suffer from anxiety and depressive disorder than men. For example, stronger associations were found between short-term exposure to air pollutants and anxiety hospitalisations in females, especially in urban environments. This vulnerability could be primarily linked to sex differences in biological susceptibility, genetic and hormonal factors, physiological stress responsivity, sociocultural aspects, and/or environmental risk factors.  

Children 

Children and adolescents are particularly susceptible to air pollution due to the development of their respiratory and nervous systems. Pollutants, especially fine and ultrafine particles, can invade a pregnant female’s respiratory barrier, pass into the maternal bloodstream, and cross the placental barrier by direct transport, suggesting that pollutants inhaled by pregnant females can directly reach the placenta and developing fetus and pass the fetal blood-brain barrier. For example, particulate matter (PM) is associated with post-neonatal mortality with congenital malformations of both the nervous and gastrointestinal systems and endocrine causes in infant deaths. Since children’s breathing rate is higher, and they have less developed natural lung barriers than adults, they absorb more pollutants with the air they inhale and spend more time outdoors, making them highly sensitive and susceptible to airborne contaminants. As a result, children suffer neural, behavioral, and cognitive changes linked to lower IQ and increased risks of anxiety, depression, and cognitive deficits associated with traffic air pollution exposure.

Children exposed to air pollution, especially at higher levels, often experience psychopathology during the transition to adulthood, leading to continued depressive and anxiety disorders, suicidal behaviour, and psychiatric hospitalisation, as well as academic failure, recurrent unemployment, and relationship difficulties. 

Like adults, children with psychiatric disorders are often undertreated, as 70-80% of depressed children receive no treatment. Identifying and intervening in modifiable environmental exposures, including air pollution, associated with childhood depression and anxiety is a significant public health challenge, given that childhood mental health disorders often persist into adulthood.

Elderly

The elderly population is also at a heightened risk due to age-related declines in health and the pre-existence of chronic conditions such as cardiovascular, respiratory disease and diabetes, which can be exacerbated due to exposure to adverse air quality. Depression and anxiety are one of the common mental health disorders experienced by the elderly, affecting over 5-7% of the global population over 60. Generally, cognitive impairment (for example, dementia) and depression are the most common mental and neurological disorders later in life that are often experienced simultaneously. It is more common for the elderly to spend more time alone and indoors. Therefore, loneliness and social isolation are linked to higher levels of depression and anxiety. Additionally, the elderly may have diminished physiological resilience, making it more difficult for their bodies to cope with the oxidative stress and neuroinflammation caused by air pollution.

Socioeconomic Disparities and Environmental Stressors

Socioeconomic and environmental stressors further complicate the relationship between air pollution and mental health. Socioeconomic status (SES) is critical in determining exposure to air pollution and the resultant health impacts. The World Health Organization (WHO) reported that 91% of the world’s population lives where air quality exceeds WHO guideline limits, with 4.2 million premature deaths resulting from ambient air pollution, while on average, 7.3 billion people are directly exposed to unsafe average annual PM2.5 concentrations, 80% of whom live in low- and middle-income countries, estimating subnational poverty across 211 countries and territories. Consequently, 98.6% of the 2.8 billion people exposed to hazardous PM2.5 levels (over 35 µg/m³) live in middle-income countries. The compounded stress from socioeconomic disadvantages and environmental hazards can lead to greater mental health challenges in these populations.

Lower SES populations often reside in areas lacking green spaces and higher pollution levels due to close proximity to industrial zones, heavy traffic, and other pollution sources, and work in jobs involving harmful exposures. These communities also tend to have less access to healthcare and other resources that can mitigate the adverse effects of pollution. The compounded stress from socioeconomic disadvantages and environmental hazards can lead to greater mental health challenges in these populations, less life satisfaction, and deaths.

Differential patterns of exposure may be exacerbated by environmental injustices that disproportionately affect Black, Indigenous, and people of color as well as ethnic groups.  Historical factors such as redlining, where financial services such as home loans were denied to residents of certain areas based on discriminatory lending practices, and segregation have long-lasting impacts on socioeconomic status and play significant roles in confining minority populations to low-income areas. These same populations may have less access to resources such as education on the effects of environmental exposures, economic and social resources to relieve stress in response to air pollution, and quality health care to prevent or treat mental illness, exacerbating the vulnerabilities of these populations.

You might also like: Understanding the Risks of Extreme Heat

Conclusion

The relationship between air pollution and mental health is complex and multifaceted, with significant implications for vulnerable populations such as pregnant women, the elderly, individuals with pre-existing health conditions, and children. Evidence suggests that exposure to air pollutants not only exacerbates existing mental health disorders like anxiety and depression but also contributes to the development of new psychological challenges, particularly during critical periods such as pregnancy and childhood.

Addressing these challenges requires a comprehensive approach that includes reducing air pollution levels, improving access to mental health care, and implementing targeted interventions for those most at risk. By recognizing the interconnectedness of environmental and mental health factors, public health strategies can be better designed to protect and enhance the well-being of vulnerable populations, ultimately leading to healthier communities and improved quality of life. 

The urgency of addressing these issues is underscored by the growing body of evidence linking air pollution to adverse mental health outcomes, making it imperative to prioritize both environmental and mental health in public policy and research.

Featured image: Raunaq Chopra/Climate Visuals Countdown.