Ozone pollution causes substantial hospital admissions for heart attack, heart failure and stroke

(IN BRIEF) The European Heart Journal, a journal of the European Society of Cardiology (ESC), has published a new study revealing that surpassing the World Health Organization’s (WHO) ozone limit is associated with significant increases in hospital admissions for heart attack, heart failure and stroke. The research also found that even ozone levels below the WHO maximum were linked with worse health outcomes. The study examined data on daily hospital admissions for cardiovascular disease from 70 cities in China between 2015 and 2017, covering approximately 258 million people. The study found that daily exposure to ambient ozone was associated with increased hospital admissions for all cardiovascular diseases studied, except for haemorrhagic stroke, independent of other air pollutants. The study found that even lower concentrations of 70 to 99 µg/m3, compared to levels below 70 µg/m3, were also linked with increased hospital admissions for heart failure, stroke and coronary heart disease. The researchers estimated that 3.42%, 3.74% and 3.02% of hospitalizations for coronary heart disease, heart failure and stroke, respectively, were attributable to ozone pollution during the study period. The research emphasizes the urgent need to reduce ozone pollution and protect public health.

(PRESS RELEASE) SOPHIA ANTIPOLIS, 10-Mar-2023 — /EuropaWire/ — The European Society of Cardiology (ESC), an independent, nonprofit organisation aiming to reduce the burden of cardiovascular disease, announces that a new study published in the European Heart Journal, a publication of the ESC, has found evidence linking ozone pollution to increased hospital admissions for heart attack, heart failure, and stroke. The study provides the first evidence that exceeding the World Health Organization (WHO) ozone limit can cause substantial harm to human health, even at levels below the WHO maximum.

“During this three-year study, ozone was responsible for an increasing proportion of admissions for cardiovascular disease as time progressed,” said study author Professor Shaowei Wu of Xi’an Jiaotong University, China. “It is believed that climate change, by creating atmospheric conditions favouring ozone formation, will continue to raise concentrations in many parts of the world. Our results indicate that older people are particularly vulnerable to the adverse cardiovascular effects of ozone, meaning that worsening ozone pollution with climate change and the rapid ageing of the global population may produce even greater risks of cardiovascular disease in the future.”

Ozone is a gas that forms when other pollutants, such as volatile organic compounds and nitrogen oxides, react in the presence of sunlight. Ozone pollution is different from the ozone layer, which protects the Earth from harmful UV radiation.

The study examined data on daily hospital admissions for cardiovascular disease in 70 cities in China between 2015 and 2017, covering over 258 million people. The types of cardiovascular disease included coronary heart disease, stroke, and heart failure, among others.

The researchers found that exposure to ambient ozone was associated with increased hospital admissions for all cardiovascular diseases studied, except for haemorrhagic stroke, independent of other air pollutants. For example, each 10 μg/m3 rise in the two-day average eight-hour maximum ozone concentration was associated with a 0.40% increase in hospital admissions for stroke and 0.75% for acute myocardial infarction.

Professor Wu said: “Although these increments look modest, it should be noted that ozone levels may surge to higher than 200 μg/m³ in summer, and these increases in hospitalisations would be amplified by more than 20 times to over 8% for stroke and 15% for acute myocardial infarction.”

The study also estimated the excessive admission risk for cardiovascular disease associated with ozone concentrations at or above the WHO air quality guideline (100 µg/m3) compared to levels below 70 μg/m3, which are mostly naturally occurring and not due to human activity. Levels of 100 µg/m3 or higher were found to be associated with substantial increases in hospital admissions for cardiovascular disease, ranging from 3.38% for stroke to 6.52% for acute myocardial infarction. Lower concentrations of 70 to 99 µg/m3 (vs. below 70 μg/m3) were also linked with increases in hospital admissions, ranging from 2.26% for heart failure to 3.21% for coronary heart disease.

Professor Wu said: “This suggests that 109,400 coronary heart disease admissions could have been avoided if ozone concentrations were 0 µg/m³. This may be impossible to achieve given the presence of ozone from natural sources. However, we can conclude that considerable numbers of hospital admissions for cardiovascular disease could be avoided if levels were below 100 μg/m³, with further reductions at lower concentrations.”

The study found that ozone pollution was responsible for 3.42%, 3.74%, and 3.02% of hospitalisations for coronary heart disease, heart failure, and stroke, respectively, during 2015 to 2017. The proportions increased with time when each year was analyzed separately.

These findings suggest that reducing ozone pollution could help reduce the burden of cardiovascular disease in affected areas.

In an accompanying editorial, Professor Thomas Münzel and co-authors said: “Projections for Europe suggest that ozone will play a more dominant role as a health risk factor in the future due to climate change with rising temperature and, accordingly, increasing photochemical formation of ozone. The strong link between climate change and air quality means that reducing emissions in the long term to tackle global warming will play a key role in alleviating ozone pollution and improving the air that we breathe.”