Ozone Levels Linked to Cardiac Arrest

Researchers at Rice University (Texas, USA) reveal a direct correlation between out-of-hospital cardiac arrests and levels of air pollution and ozone.  Katherine Ensor and colleagues  analyzed eight years' worth of data drawn from the city of Houston's (Texas, USA) extensive network of air-quality monitors and more than 11,000 concurrent out-of-hospital cardiac arrests (OHCA) logged by Houston Emergency Medical Services (EMS). They found a positive correlation between OHCAs and exposure to both fine particulate matter (airborne particles smaller than 2.5 micrograms) and ozone.   Specifically, the team 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%, with particular impact on those with pre-existing (and not necessarily cardiac-related) health conditions. Increases in ozone level were similar, but on a shorter timescale: Each 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%.  Observing that Relative Risks were higher for men, African-Americans and people over 65, the study authors warn that: “The findings confirm the link between OHCA and [fine particulate matter] and introduce evidence of a similar link with ozone.”