A study involving more than 3,000 US counties, with a total population of 315 million residents, has found a connection between air pollution, mental well-being, and the risk of dying from cardiovascular disease before the age of 65. The research, presented at ESC Preventive Cardiology 2024, suggests that the air we breathe affects our mental health, which in turn impacts heart health.
Fine Particles Pose the Highest Health Risk
The study focused on fine particles, or PM2.5, which are less than 2.5 micrometres in diameter and come from sources such as vehicle exhaust fumes, power plant combustion, and burning wood. These particles present the highest health risk. The researchers obtained county-level data on annual PM2.5 levels from the Centers for Disease Control and Prevention (CDC) and categorized PM2.5 exposure as high or low according to World Health Organization (WHO) standards.
The team also gathered data on the average number of days that county residents experienced mental health issues, including stress, depression, and emotional problems, from the CDC. Counties were then categorized into three groups based on these numbers, with those in the top third reporting the most days of poor mental health (PMH).
Dirty Air, Poor Mental Health, and Premature Cardiovascular Mortality
The study found that counties with dirty air (high PM2.5 concentrations) were 10% more likely to report high levels of PMH days compared to counties with clean air (low PM2.5 concentrations). This risk was notably higher in counties with a high prevalence of minority groups or poverty. The link between PMH and premature cardiovascular mortality was strongest in counties with air pollution levels above WHO recommended levels (≥10 µm2).
In these counties, higher levels of PMH were associated with a three-fold increase in premature cardiovascular mortality compared to lower PMH levels. Moreover, one-third of the pollution-related risk of premature cardiovascular deaths was explained by the increased burden of PMH.
“Our results reveal a dual threat from air pollution: it not only worsens mental health but also significantly amplifies the risk of heart-related deaths associated with poor mental health,” said study lead author Dr. Shady Abohashem of Harvard Medical School, Boston, US. “Public health strategies are urgently needed to address both air quality and mental wellbeing in order to preserve cardiovascular health.”
The findings highlight the need for comprehensive public health strategies that tackle both air pollution and mental health to reduce the risk of premature cardiovascular mortality.