WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
By Dr. Mercola
There is an epidemic of heart disease in the U.S. and conventional treatments are not proving to be as effective as hoped. Some of the factors associated with an increased risk of heart disease are obesity, high blood pressure, smoking and diabetes. These factors may lead to a heart attack, during which part of the heart is deprived of oxygen, slowly killing the muscle.
In the case of sudden cardiac arrest (SCA), the heart experiences an electrical event causing it to suddenly and unexpectedly stop beating. The individual suddenly loses consciousness as the brain is deprived of oxygen. Without immediate medical attention the individual may die within minutes, in which case it would be deemed a sudden cardiac death (SCD).1
Just as there are physiological differences between a heart attack and SCA, there are also different factors triggering each event. While heart attacks are caused by mitochondrial dysfunction, impaired microcirculation to your heart and chronically suppressed parasympathetic nervous system activity, SCA is triggered by an arrhythmia affecting the electrical system of the heart. Researchers have now discovered an association between exposure to cool air and air pollution, and an increased risk of SCD.2
Prevalence of Sudden Cardiac Death Remains High
While the number of deaths attributed to heart disease has steadily declined over the past two decades,3 falling more than 25 percent from 2004 to 2014,4 the prevalence of SCD has remained steady.5 SCD accounts for greater than 50 percent of all deaths related to heart disease and nearly 20 percent of overall deaths. The incidence of SCD in the U.S. ranges between 180,000 and 450,000 cases annually.
The estimates vary widely as the definitions and surveillance for SCD are difficult to ascertain.6 For the most part, SCD refers to an unexpected death related to a cardiovascular event in a person with or without pre-existing heart disease. Despite improvements in resuscitation and post resuscitation care, survival to hospital discharge after an SCA is estimated at only 7.9 percent.7 Additionally, many of these events occur at home where they are unwitnessed.
Reducing the number of individuals succumbing to SCD requires an in-depth understanding of the epidemiology, reducing risk potential and applying interventions many in the population may easily access. The American Heart Association estimates there are more than 356,000 out-of-hospital SCAs annually and over 90 percent are fatal.8
In contrast, there are about 790,000 people who have a heart attack each year and 114,000 die from the event, or 14.4 percent.9 SCA is the leading medical cause of death in athletes. A comprehensive literature search and review found rates could vary between 1 in 917,000 and 1 in 3,000 athletes. Those who have a higher risk appear to be black, male basketball players.10
Small Particulate Matter and Cold Weather May Trigger Cardiac Arrest
In research from Brigham and Women's Hospital in Boston, researchers studied 112,000 women between 1999 and 2011 who were enrolled in the Nurse's Health Study, an ongoing study beginning in 1976.11 During the study period researchers found 221 SCDs associated with lower temperatures and higher levels of particulate matter.
Particulate matter (PM), also known as particulate pollution, is a mix of small particles and liquid droplets in the air. Researchers were interested in particles less than 2.5 microns in size. PM2.5 is so tiny the particles can get deep into your lungs and even pass into your bloodstream,12 as they are 30 times smaller than the diameter of a human hair.
The researchers evaluated both the amount of particulate matter in the air and the temperature on the day SCD occurred. They found increasing levels of PM 2.5 were associated with a 22 percent higher risk of SCD. When the temperature dropped below 55 degrees Fahrenheit (F), the odds increased 2.6 times higher than over 55 degrees F.13 Interestingly, once the temperature dropped below 39 degrees F., the risk also leveled off. There was no increase risk in temperatures above 55 degrees.
The women who suffered SCD during the study had no underlying heart disease the researchers could determine. The researchers also found that other risk factors for heart disease, including age, weight and smoking, did not appear to affect the risk of SCD. Hart commented,14 "The risk of this outcome is extremely low for an individual woman. It's on a population level where we're concerned." The researchers also noted that while the participants in the study were all women, they would expect similar results in men.15
Even a small amount of air pollution on colder days could increase your risk of experiencing cardiac arrest. Dr. Kevin Marzo, chief of cardiology at New York University Winthrop Hospital was not involved in the study. However, after having reviewed the results, he commented the presence of cold weather and air pollution may produce a perfect storm, increasing inflammation and constricting blood supply to the heart so even healthy women had an increased risk of sudden death.16
How Air Pollution Affects Your Heart
Nearly 92 percent of the world population breathe polluted air.17 Often, both your indoor and outdoor air is polluted, but with different toxins. According to a study from the International Energy Agency, 6.5 million people worldwide die each year due to exposure to air pollution.18 Past research found a link between air pollution and cardiovascular disease, and more recently researchers have found how microscopic particles enter the bloodstream and affect the heart.19
Using both human and mouse models, researchers determined microparticles access the bloodstream through the lungs, some having an affinity for accumulating in damaged or inflamed areas of your vascular system.20 Some of the particles were detected in the urine of the subjects nearly three months after testing had been completed.
In another study,21 researchers worked with participants who were scheduled for removal of damaged blood vessels, which put them at high risk for a heart attack or stroke. On the day prior to surgery, the participants inhaled gold nanoparticles. Once the vessels were removed and analyzed, the researchers found that within 24 hours the vessels had accumulated the gold nanoparticles in the damaged areas.22
It has become clear that air pollution damages your lung and vascular tissues. Major components of outdoor air pollution include carbon monoxide, phytochemical oxidants, sulfur dioxide, mercury, nitrogen oxides and lead.23 Chemicals include inorganic and organic compounds, ranging from those large enough to be seen by the naked eye to nanoparticles that may easily slip into your bloodstream.24
Cold Weather May Trigger a Heart Attack or SCD
Cold air is a secondary risk factor for heart attack and SCD. According to the American Heart Association,25 nearly every 40 seconds someone in America has a heart attack. In cold weather, especially during rapid changes in weather, it's more likely your blood vessels will constrict.
If you already suffer from narrowing of the blood vessels related to underlying heart disease, this additional restriction to vital organs can lead to minimizing blood flow to the heart, chest pain and potentially a subsequent heart attack.26 Additionally, cold weather puts a strain on your circulatory system, increasing your risk of loss of oxygen to your heart muscle. Increasing physical activity, such as shoveling snow in cold weather, can place additional stress on your heart.
Although researchers are unsure of the exact physiological reason, they know the risk of SCD increases during cold weather. A recent study published in the BMJ27 evaluated over 3,500 autopsy-verified cases of SCD in Finland.
They concluded there was an association between cold spells and SCD, strongest during the autumn months. Another study performed in Minnesota28 came to a similar conclusion after evaluating the incidence of heart attacks and SCDs from 1979 to 2002. Their data suggested a peak in SCD during the winter months was accounted for by the cooler weather.
Evaluating short-term exposure to the cold in middle-aged hypertensive men,29 researchers found an alteration in cardiac repolarization and regulation resulting in changes to the participants' EKG readings. Exposure to dry air and lower temperatures was also associated with the onset of atrial fibrillation in patients who had known cardiac disease.30 Atrial fibrillation is an arrhythmia, or abnormal heartbeat.
In an analysis of 48 trials,31 researchers found SCD was the most common cause of death in patients who had atrial fibrillation. SCD accounted for greater than 20 percent of all deaths in the patient population, representing a 2.5 increased risk over those who did not have atrial fibrillation. Another meta-analysis demonstrated a statistically significant increased risk of SCD in those who also suffer with atrial fibrillation in the general population.32
Changing EPA Standards May Increase Air Pollution in the US
Based on the results from Hart's study, which occurred under the current EPA standards for air pollution, the standards are protective enough, and Hart expressed concern that the Trump administration will increase health risks if they're successful in rolling back regulations.33
Vice president of the Health Effects Institute, Bob O'Keefe, believes the gap between the most polluted air and the least polluted air is striking, as developed countries have made moves to clean air pollution and developing countries have fallen further behind while concentrating on economic growth.34 A report by the Institute reinforces data demonstrating air pollution is contributing toward a rising number of deaths.35 As air pollution does not respect country boundaries, it is vital every country seeks to reduce pollution.
Data from satellites and ground monitoring reveal health risks are rising from breathing dirty air. However, while many consumer protection advocacy programs are fighting to clean the air you breathe, it appears efforts led by the Trump administration could lead to worse air quality in America.36
The American Lung Association (ALA) called out Congress and the Environmental Protection Agency in their State of the Air report for six threats to the nation's air quality, including steps being taken by the administration to weaken enforcement of key safeguards required in the Clean Air Act.37
Current legislation to weaken the Clean Air Act includes repealing plans to reduce carbon pollution from power plants and removing limits on emissions from oil and gas operations, each contributing to increasing particulate air pollution and raising your health risks.38 ALA national president and CEO Harold P. Wimmer said in a press release:39
"The Clean Air Act has saved lives and improved lung health for nearly 50 years. Congress and the EPA are tasked with protecting Americans — including protecting the right to breathe air that doesn't make people sick or die prematurely. We call on President Trump, EPA Administrator Scott Pruitt and members of Congress to fully fund, implement and enforce the Clean Air Act for all pollutants — including those that drive climate change and make it harder to achieve healthy air for all."
Protect Your Health and Home From Air Pollution
Marzo recommends reducing your exposure to air pollution and cold air by limiting your outdoor workouts on days when pollution levels are high, and especially when the temperatures are below 55 degrees F.40 Strategies that will help reduce your exposure to indoor air pollution can be found in my previous article, "The Air We Breathe Is More Polluted Than You Know."
Lastly, while you don't have any control over outdoor air pollution, there are dietary measures that can help buffer the effects. Overall, seek to eat a diet of whole foods, rich in anti-inflammatory vegetables and healthy fats. Among the most important dietary interventions to consider are:41
• Animal-based omega-3 fats: In a study of 29 middle-aged people, animal-based omega-3 supplementation reduced some of the adverse effects to heart health and lipid levels, including triglycerides, occurring with exposure to air pollution (olive oil did not have the same effect).42
• Broccoli sprouts: Broccoli sprout extract was shown to prevent the allergic nasal response occurring upon exposure to particles in diesel exhaust, leading the researchers to suggest broccoli or broccoli sprouts could protect against air pollution's effect on allergic disease and asthma.43 A broccoli sprout beverage also enhanced detoxification of some airborne pollutants in residents of a highly polluted region in China.44
• Vitamins C and E: Among children with asthma, antioxidant supplementation including vitamins C and E helped to buffer the impact of ozone exposure on their airways.45
• B vitamins: A small-scale human trial found high doses of vitamins B6, B9 and B12 in combination completely offset damage caused by very fine particulate matter in air pollution.46 Four weeks of high-dose supplementation reduced genetic damage in 10 gene locations by 28 to 76 percent, protected mitochondrial DNA from the harmful effects of pollution, and even helped repair some of the genetic damage.