Scientists have discovered a link between pollution, stress and depression, which puts middle-aged adults living in areas with poor air quality at a higher risk of dying of heart disease.
Researchers in the US studied concentrations of tiny particles known as PM2.5 in the air across 3,000 counties, home to 315 million residents.
They found a relationship between the air people breathe, and their mental well-being and cardiovascular health.
“Our study indicates that the air we breathe affects our mental well-being, which in turn impacts heart health,” said study lead author Dr Shady Abohashem of the Harvard Medical School in Boston, the US.
Mental illness and air pollution have been linked to premature death in past studies.
The researchers wanted to know whether air pollution and poor mental health are interrelated and have a joint impact on death from cardiovascular disease.
They focused on particles less than 2.5 micrometres in diameter, which come from vehicle exhaust fumes, power plant combustion and burning wood, and present the highest health risk.
Exposure to PM2.5 was categorised as high or low, according to standards set by the World Health Organisation.
The researchers then gathered data on the average number of days that residents suffered from mental health issues such as stress, depression and emotional problems.
Each county was categorised into three groups based on the numbers.
The researchers found that counties in the top third reported the most days of poor mental health.
Counties with the most PM2.5 concentrations were 10 per cent more likely to report high levels of poor mental health days, compared to those with cleaner air.
The risk was “markedly” greater in counties with a high prevalence of minority groups or poverty, said researchers.
The link between poor mental health and premature death due to heart disease was strongest in counties with higher levels of air pollution.
In these counties, higher levels of poor mental health were associated with a three-fold increase in premature cardiovascular mortality, compared to areas with better well-being.
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The researchers said a third of the pollution-related risk of premature cardiovascular deaths was explained by the increased burden of poor mental health.
“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 Dr Abohashem.
“Public health strategies are urgently needed to address both air quality and mental wellbeing in order to preserve cardiovascular health.”
The findings will be presented on Friday at ESC Preventive Cardiology 2024 in Athens.
Recent research found that Google Street View could be used to predict coronary heart disease risk by analysing neighbourhood environments.
The study, published in European Heart Journal, monitored everyday surroundings, including the quality of roads, buildings and green spaces, and the role they play in determining heart health.
Top 10 least-polluted countries – in pictures
Researchers were able to track the link between these environmental elements, including the presence or absence of pollution, and the risk of coronary heart disease – a condition where the heart's arteries are blocked, limiting blood flow to the heart.
They found that these neighbourhood characteristics could account for 63 per cent of the differences in heart disease risk from one community to another.
