(ORDO NEWS) — Nearly a decade of data collected in Singapore suggests that elevated concentrations of tiny particles in the air can trigger cardiac arrest, making the need to reduce global air pollution even more urgent.
The researchers looked for particles at least 25 times smaller than the width of a human hair, known as PM2.5 particles (2.5 micrometers in diameter). Their small size means they are easy to inhale and have been linked to a range of health problems, including autoimmune diseases.
In this study, pollution levels in Singapore were tracked from over 18,000 reported cases of out-of-hospital cardiac arrest (OHCA) between July 2010 and December 2018. Using statistical analysis, 492 cases could be attributed to an increase in PM2.5 concentration.
“We have clear evidence of a short-term association of PM2.5 with out-of-hospital cardiac arrest, which is a catastrophic event that often leads to sudden death,” says epidemiologist Joel Eyck of the Duke-NUS School of Medicine at the National University of Singapore.
This is an observational study, so we can only speculate about the association between pollution levels and cardiac arrests. Moreover, air pollution measurements taken at air quality monitoring stations may not reflect individual exposure.
However, the data obtained are sufficient to suggest that this relationship is worth exploring in more detail. The data showed that the daily concentration of PM2.5 averaged 18.44 micrograms per cubic meter.
After testing hypothetical reductions in air pollution levels, the researchers found that a 1 microgram per cubic meter reduction resulted in an 8 percent reduction in heart attacks, and a 3 microgram per cubic meter reduction resulted in a 30 percent reduction.
Hypothetically, such a decrease leads to a decrease in the number of heart attacks by 39 and 149, respectively.
There was also a clear reduction in the risk of heart attack 3-5 days after exposure to higher levels of pollution, suggesting a short-term effect. Purifying urban air could save lives and reduce the burden on hospitals, researchers say.
“These results clearly show that efforts to reduce air pollution levels of particles in the 2.5 microgram range or below, as well as measures to protect against exposure to these particles, can play a role in reducing sudden cardiac arrest in the population of Singapore, as well as reduce the burden on health services,” says Hayk.
The survival rate for sudden cardiac arrest is typically around 10 percent, which is much lower than the chances of surviving a heart attack in a hospital. Therefore, it is not an exaggeration to say that reducing the number of such cases saves lives. We can add this to the long list of reasons why we should clean our air.
Although this association had been seen before in cities such as New York and Melbourne, Australia, the results were not consistent with data collected elsewhere, such as Denmark.
These discrepancies typically occur when pollutant concentrations fall below World Health Organization air quality guidelines, but studies show that there is no “safe” level of exposure for the population’s heart health.
What is clear is that most of us breathe poor quality air, which is thought to be responsible for millions of premature deaths in urban and rural areas every year.
The authors of the new study want places like Singapore to do more to control air quality. With everything from traffic jams to wildfires at play in this process, there are plenty of places to start making progress, including indoors.
“This study provides compelling evidence for the impact of air quality on health and should stimulate policy and ground-based efforts to manage key emissions that could increase PM2.5 and prevent potential harm to public health,” says Markus Ong, Clinical Scientist from Duke-NUS Medical School.
“New policy measures, such as phasing out combustion engine vehicles, could help reduce the danger.”
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