At the American Association for the Advancement of Science (AAAS) conference in Boston, Rice statisticians Katherine Ensor and Loren Raun announced their findings, which they derived from a huge data set completely unique to Houston. Houston is ranked eighth in the United States for high-ozone days. This inspired the Rice researchers to find a link between cardiac arrest and ambient ozone levels.
Eight years’ worth of data were analyzed. This data, taken from Houston’s extensive network of air quality monitors, focused on 11000 concurrent out-of-hospital cardiac arrests (OHCA) logged by the Houston Emergency Medical Services (EMS). There was indeed a positive correlation between OHCAs and exposure to fine particulate matter and ozone.
The researchers found that a daily average increase in particulate matter of 6 micrograms per day over two days raised the risk of OHCA by 4.6. Those with pre-existing (and not necessarily cardiac-related) health conditions were at increased risk. Increases in ozone levels were similar, only on a smaller timescale. Every increase of 20 parts-per-billion over one to three hours also increased OHCA risk, with a peak of 4.4%. Peak-time risks from both pollutants rose as high as 4.6%. People over the age of 65 and African Americans were at higher risk.
The researchers said their goal was ultimately to save lives by contributing to a warning system that lets at-risk individuals the daily particulate matter and ozone levels. Both researchers concurred that general blanket warnings about air quality are not enough to save lives.
Ensor and Raun also plan make to make people aware of the massive health cost of pollution and hope that awareness and education will lead to major changes.
Details of the study are to be published in the American Heart Association journal Circulation.