Exceeding the World Health Organisation (WHO) ozone limit is associated with increases in hospital admissions for heart attack, heart failure and stroke, says a study by the European Society of Cardiology (ESC).
The study, authored by Prof. Shaowei Wu of Xi’an Jiaotong University, China, was published in European Heart Journal, a publication of ESC, and posted on its website on Friday, March 10, 2023.
Ozone is a gas and the main air pollutant in photochemical smog, while ozone pollution is formed when other pollutants react in the presence of sunlight.
These pollutants are emitted by motor vehicles, power plants, industrial boilers, refineries, chemical plants, biomass and fossil fuel burning facilities.
Wu said that even ozone levels below the WHO maximum were linked with worsened health.
“During this three-year study, ozone was responsible for an increasing proportion of admissions for cardiovascular disease as time progressed.
“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,” he said.
According to Wu, the study examined the association between ambient ozone pollution and hospital admissions for cardiovascular disease.
He said that data on daily hospital admissions for cardiovascular disease between 2015 to 2017 in 70 cities in China were collected from the two main national health insurance systems.
“During the study period, the two databases covered approximately 258 million people across the 70 cities, equivalent to more than 18 per cent of China’s population.
“The types of cardiovascular disease included coronary heart disease, stroke and heart failure, plus subtypes such as angina, acute myocardial infarction, acute coronary syndrome, ischaemic stroke and haemorrhagic stroke.
He said during the study period, there were 6.44 million hospital admissions for cardiovascular disease in the 70 cities and the average daily eight-hour maximum ozone concentration was 79.2 μg/m3.
“Exposure to ambient ozone was associated with increased hospital admissions for all cardiovascular diseases studied except haemorrhagic stroke, independent of other air pollutants,” he said.
He noted that these increments might look modest, saying that ozone levels may surge to higher than 200 μg/m3 in summer.
According to him, these increases in hospitalisations would be amplified by more than 20 times to over eight per cent for stroke and 15 per cent for acute myocardial infarction.
He noted 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.
Similarly, Prof. Thomas Münzel, co-author of the study, said the strong link between climate change and air quality means that reducing emissions in the long term to tackle global warming would play a key role in alleviating ozone pollution and improving the air that we breathe.
By Oluwafunke Ishola