The researchers found that airborne polluting particles were linked to cardiac arrest

According to scientists at the Pan-Asian Recovery Outcomes Study (PAROS), a collaboration between Duke-NUS School of Medicine and the National Environment Agency (NEA), small particles in Singapore's air pollution can cause cardiac arrest
in some people who are not hospitalized but are just living normal lives.
The findings, published in The Lancet Public Health, are based on data collected between 2009 and 2018 and address uncertainties
caused by inconsistent early studies due to the availability and quality of environmental and disease data.

The research team, which included members from the National Energy Administration's Environmental Health Institute and the Clean Environment Group's Environmental Monitoring and Modeling Unit, evaluated whether there was a correlation
between out-of-hospital cardiac arrest (OHCA) and levels of tiny air pollution particles (at least 25 times smaller than the width of a hair).
Previous studies have shown that PM2.
5, a particulate matter, significantly increases the risk of
cardiovascular, respiratory and even eye diseases.

Joel Aik, principal investigator and adjunct assistant professor at Duke-NUS Centre for Former and Emergency Studies (PERC), said: "We have clear evidence of a short-term link between PM2.
5 and out-of-hospital cardiac arrest, a catastrophic event
that often leads to sudden death.
"

The methodology used in this study is similar to that used in the study cited by the World Health Organization for the development of air quality guidelines, and its conclusions are based on data on
all OHCA cases reported to PAROS in Singapore between 1 July 2009 and 31 December 2018.
The timing of the occurrence of these cases was compared
to the daily air pollution levels over the same period.

The statistical analysis found that of the 18,131 OHCA events, the researchers were able to attribute 492 to an increase
in PM2.
5 concentrations on the day of cardiac arrest or two days earlier.
The study also found a significant reduction in risk within 3 to 5 days of exposure to pollutants, suggesting a relatively short-term
effect.

The average concentration of PM2.
5 during the study period was 18.
44 micrograms per cubic meter, and a reduction of 1 microgram reduced the number of OHCA events by 8%, while a reduction of 3 micrograms reduced the number of OHCA events by 30%.

"These results clearly show that efforts to reduce air pollution particulate levels to the range of 2.
5 micrograms or less, and taking steps to prevent exposure to these particles, can play a role in reducing cardiac arrest in Singapore's population, while also reducing the burden on health services," said Dr Ai, who is also an environmental epidemiologist
at the National Energy Administration.

He highlighted the study's relevance
to many of the world's cities where air pollution is a daily problem.
Less common but extreme events, such as smog and wildfires, can also cause sudden and dramatic increases in
PM2.
5 particles.
While the findings are consistent elsewhere and the biological mechanisms of PM2.
5's effects on OHCA events seem plausible, he cautions that this is an observational study and does not imply direct causation
.

Professor Marcus Ong, Director of the Health Services and Systems Research Program and Chair of PAROS at Duke-NUS, said: "This study provides strong evidence of the health impacts of air quality and should stimulate policy and ground efforts to manage emissions from the main sources that can lead to an increase in PM2.
5 and prevent potential harm
to public health.
" "New policy interventions, such as phasing out internal combustion engine vehicles, can help reduce dangers
.
"

Professor Ong, who is also a senior advisor to the Department of Emergency Medicine at Singapore General Hospital, added: "Individuals can also take simple but important steps, such as wearing high-efficiency air filtering masks when PM2.
5 levels are elevated and not smoking
.
"