Q&A with Dr. Vivian Pun Vital Strategies’ air pollution epidemiologist in the Environmental Health Division
The health effects of air pollution reach far beyond the respiratory system, or even our physical health. Air pollution also impacts our mental health. We spoke to Dr. Vivian Pun, epidemiologist in Vital Strategies’ Environmental Health Division, to learn more about her work. Vivian’s research, Association of Ambient Air Pollution with Depressive and Anxiety Symptoms in Older Adults, was one of the first studies to observe a relationship between air pollution and mental health. The study was recently included in a newly curated collection of articles compiled by the prestigious Environmental Health Perspectives in their 2019 Journal Impact Factor.
What inspired you to research the link between air pollution and mental health?
Air pollution exposure is ubiquitous and it is important for us as epidemiologists to understand the direct health links of the air we breathe. At the time of this publication in 2017, little was known about the linkage between air pollution and mental health. One of the mechanisms underlying mental disorders is believed to occur through the inflammation of the brain and oxidative stress, an imbalance between reactive oxygen molecules and their neutralizing counterparts. Oxidative stress can damage our cells, including DNA and proteins. As air pollution is a known source of environmentally-induced inflammation and oxidative stress, my colleagues and I wondered if it might play a role in the development of mental disorders.
I studied air pollution’s impact on cardio-respiratory illnesses during my doctorate work, and upon graduation I joined the research team at Northeastern University in Massachusetts, U.S. Our work focused on the influence of air pollution, neighborhoods and lifestyle on cardiac health, but also on cognitive and mental health in older adults in the U.S. Common mental health disorders such as depression affect nearly 300 million people worldwide. The focus on mental health is particularly important because mental disorders can stealthily affect one’s quality of life, work performance, and social well-being.
Does air pollution affect depression and anxiety? If so, how?
Our study focused on the impact of exposures to fine particulate matter (PM2.5), the pollutant that poses the greatest risk to health, among 4,000 older adults living across the United States. PM2.5 can penetrate deep into the lungs and travel to other organs, causing serious illnesses and even death. We found that long term exposure to PM2.5 levels was significantly associated with moderate-to-severe anxiety symptoms and depressive symptoms, respectively. Our study was among the first to observe such a relationship, especially for depressive symptoms; and was subsequently supported by growing evidence linking air pollution exposure with a range of mental health illnesses (e.g., depression, anxiety, bipolar, suicidal risk) among among adults, and recently in children and adolescents.
How this happens remains poorly understood, but most likely, several factors work together towards this outcome. It has been suggested that PM2.5 may increase inflammation, oxidative stress, damage to blood vessels and degeneration in the brain. This can trigger depression-like responses; increase levels of the stress hormone cortisol, and aggravate major respiratory or cardiac medical conditions (e.g., stroke).
What does this mean in terms of the impact of air pollution on any given population?
Findings from our study and other literature suggest that breathing in PM2.5 may impact the mental health of individuals, especially those with preexisting cardiopulmonary diseases such as stroke and heart failure, and those living in communities of low socioeconomic status, high poverty and unemployment rate. These observations may be attributed to a biological mechanism, that people with preexisting conditions or those within a lower socioeconomic status may be in poorer health than people without such conditions. Observations can also be attributed to a behavioral mechanism, that people with such health conditions and socioeconomic background experience more stress.
The links between air pollution and mental disorders have important public health implications. While our study was conducted in areas with low levels of pollution (yearly average of 10 ug/m3), millions of people live in areas where air pollution levels are several times higher than this. Individuals living in areas with high levels of air pollution may be more likely to experience mental health illness. For example, physical and mental health impacts might be more pronounced for individuals in China, where the yearly air pollution level is 53 ug/m3. As COVID-19 continues to spread, stretching global healthcare systems and exacerbating mental health issues, it’s never been more important to clean the air and protect millions if not billions of people.
What should governments do to improve air quality levels to promote mental health?
Air pollution is preventable in most cases, and effective evidence-based solutions are available to reduce air pollution at its source. Right now, cities may be focused on battling COVID-19, but this is a marathon, not a sprint. As municipalities reopen from COVID-19 lockdowns, governments must promote a sustainable and healthier “new normal” by identifying the leading sources of air pollution in their jurisdictions, and introducing evidence-based policies to control these emissions. For example, stimulus packages should be directed toward clean industries as opposed to “dirty energy” such as fossil fuel companies. Funding to sanitize and promote safe public transport which has taken a hit due to the COVID-19 pandemic and should be put in place. When implementing these policies, governments must also consider who is most likely to be exposed and impacted by air pollution. Practical guidance, such as Vital Strategies’ Accelerating Clean Air Progress: Innovation and Action Guide, is available to provide a step-by-step approach to rapidly improving air quality in the near term while governments plan for a comprehensive air quality management plan.
It is imperative that governments raise awareness and address mental health stigma, generate mental health policies and legistlation to support and improve existing mental health systems, and ensure better access to mental health services and treatments. Ultimately, a sustained improvement in air quality, coupled with an improved mental health system, will reduce mental disorders, other non-communicable diseases and minimize the vulnerability to infectious diseases like COVID-19.