Smoke from wildfires is known to cause respiratory problems such as asthma attacks and bronchitis, but it may also increase the risk of acute heart problems such as cardiac arrest, according to the findings of a new study.

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The biggest health threat in wildfire smoke is microscopic particles that can get into your eyes and respiratory system.

“While breathing wildfire smoke is linked to respiratory problems such as asthma, evidence of an association between wildfire smoke exposure and heart problems has been inconsistent,” says study co-author Anjali Haikerwal, a doctoral candidate at Monash University in Melbourne, Australia.

The study, published in the Journal of the American Heart Association, examines the association between exposure to fine particulate matter air pollutant and the risk of heart-related incidents in the Australian state of Victoria in December 2006 and January 2007.

Victoria is particularly vulnerable to wildfires due to its climate, vegetation and protracted droughts. During these 2 months at the heart of the Australian summer, wildfires burned around 1 million hectares of land in the state, with smoke reaching cities situated far away from the source fires.

According to the study authors, wildfire smoke is one of the most important sources of fine particle air pollution, containing particles from burning vegetation, building materials and other substances. These fine particles can cause health problems if they get into the respiratory system or the eyes.

The particles in question are less than 2.5 thousandths of a millimeter in diameter – far smaller than a mote of dust and invisible to the human eye.

For the study, the researchers analyzed data from three large state-wide administrative datasets, containing information on out-of-hospital cardiac arrests, unscheduled hospital admissions and emergency department (ED) visits for cardiovascular issues during the study period.

Over 2 days, fine particle concentration in the air increased from the 25th to the 75th percentile. The researchers observed a number of risk increases that rose in association with fine particle air pollution at this time.

There was a 6.9% increase in out-of-hospital cardiac arrests, more strongly associated with men and adults over the age of 65. There was also a 2.07% increase in ED visits for ischemic heart disease and a 1.86% increase in hospitalizations for ischemic disease, with this increase more strongly associated with women and adults over 65.

An important strength of the study is that the majority of fine particle air pollution was derived from wildfires, allowing the authors to assess directly the contribution of wildfire smoke to cardiovascular health events.

“These particles may act as a trigger factor for acute cardiovascular health events,” Haikerwal states. “Do not delay seeking medical help if you experience symptoms of heart problems during smoke episodes from wildfires.”

Due to the increased incidence and frequency of wildfires in recent years, the authors suggest that further research is required to investigate in greater detail the role of fine particulate matter exposure from wildfire smoke in triggering acute coronary events.

“The knowledge and evidence resulting from such research will inform policy and practice and help build capacity in the understanding and management of adverse cardiovascular health impacts in vulnerable communities during wildfire episodes,” the authors conclude.

The Centers for Disease Control and Prevention (CDC) offer a number of tips for protecting yourself from the dangers of wildfire smoke. They recommend paying attention to local air quality reports and visibility guides if available.

When indoors, keep indoor air as clean as possible using an air conditioner, avoiding using anything that burns such as candles or cigarettes and avoiding vacuuming as this stirs up fine particulate matter that is already in the home.

“During a fire, please take precautionary measures as advised by public health officials,” Haikerwal advises. “This is especially important for older adults who are at higher risk of adverse health effects during wildfire smoke exposure.”

Wildfires are not the only things that produce fine particulate matter. Previously, Medical News Today reported on a study revealing that Independence Day fireworks cause a significant rise in air pollution by producing these polluting particles.