Ozone levels linked to cardiac arrest
The EPA safe air quality standard for such small-particle pollution is 35 micrograms per cubic meter.
Though researchers don’t fully understand how air pollution is connected to heart problems, some evidence suggests that irritants like particles and ozone entering the respiratory system create inflammation and a spike in destructive molecules called free radicals, which in turn can stress the heart.
Because there are many risk factors for cardiac arrest, an additional link to ozone could have big implications for people with chronic medical conditions living in urban areas, according to Dr. Comilla Sasson of the University of Colorado, who was not involved in the new study.
Among the most common conditions that raise the risk for cardiac arrest are “stents, heart attacks, bypass surgery, and the standard risk factors of high blood pressure, High cholesterol, asthma, emphysema, smoking and a family history or genetic factors,” according to Sasson, who works to identify communities at greatest risk for cardiac arrest.
“I would think there are a lot of folks in (urban) areas that have one or two of these conditions,” Sasson said.
Sudden Cardiac Arrest Statistics
Sudden Cardiac Arrest (SCA) is a leading cause of death in the United States, claiming an estimated 325,000 lives each year.
SCA kills 1,000 people a day or one person every two minutes.
SCA most often occurs in patients with heart disease, especially those who have congestive heart failure and have had a heart attack.
It is estimated that 95 percent of victims of cardiac arrest die before they reach a hospital or other source of emergency help.
As many as 75 percent of people who die of SCA show signs of a previous heart attack. Eighty percent have signs of coronary artery disease.
SCAs accounted for 10,460 (75.4 percent) of all 13,873 cardiac disease deaths in persons aged 35-44 years, and the proportion of cardiac arrests that occurred out-of-hospital increased with age, from 5.8 percent in persons aged 0-4 years to 61.0 percent in persons aged >85 years.
SCAs accounted for 63.7 percent of all cardiac arrests among whites, 62.3 percent among African Americans, 59.8 percent among American Indians/Alaska Natives, 55.8 percent among Asians/Pacific Islanders, and 54.2 percent among Hispanics. Whites had the highest proportion of cardiac arrests out-of-hospital, and African Americans had the highest proportion of cardiac arrests in an Emergency Department or dead on arrival.
According to the Centers for Disease Control and Prevention (CDC), deaths from sudden cardiac arrest increased 10 percent (from 2,719 in 1989 to 3,000 in 1996) in people between the ages of 15 and 34. In young women, the death rate from SCA increased 30 percent. African Americans are more likely to die from SCA than whites.
Wisconsin, Idaho, and Utah have the highest percentage of cardiac arrests.
It’s too early to make recommendations based on the new results, Ensor said, but the ultimate goal of the research is to recommend more advanced warning systems to policymakers, to alert physicians who treat high risk patients, and to make ozone forecasts more available to the public.
For example, she added, scheduling outdoor sporting events, like marathons, could be affected by pollution levels.
Sasson said, “On high ozone days or high particulate days should we tell people at high risk to stay inside? If your grandma has heart problems, maybe keep her inside today.”
SOURCE: Circulation, online February 13, 2013.
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A Case-Crossover Analysis of Out-of-Hospital Cardiac Arrest and Air Pollution
Methods and Results - The association between OHCA and air pollution concentrations hours/days before onset was assessed using time-stratified case-crossover design using 11,677 emergency medical service logged OHCA events between 2004-2011 in Houston, Texas. Air pollution concentrations were obtained from an extensive area monitor network. An average increase of 6 µg/m3 in PM2.5 2 days before onset was associated with an increased risk of OHCA (1.046; 95% CI 1.012 to 1.082). A 20 ppb ozone increase for the eight-hour average daily maximum was associated with an increased risk of OHCA on the day of the event (1.039; 95% CI 1.005 to 1.073). Each 20 ppb increase in ozone in the previous 1 to 3 hours was associated with an increased risk of OHCA (1.044; 95% CI 1.004 to 1.085). Relative risk estimates were higher for men, African Americans or those aged over 65.
Conclusions - The findings confirm the link between OHCA and PM2.5 and introduce evidence of a similar link with ozone.
Katherine B. Ensor;
Loren H. Raun;
David Persse