Duke University studies in mice shows that exposure to ozone in the lungs lowers the effectiveness of the body’s innate immune system. There has been a long-time correlation between ozone exposure and cardio-pulmonary hospitalizations /deaths, however actual causal evidence has remained inconclusive. The research team at Duke has found that ozone exposure in mice at levels approximating unhealthy levels for humans (~85 ppb as established by the EPA) appears to enhance lung injury in response to bacterial toxins, and more importantly, enhances programmed cell death (apotosis) in immune system cells that destroy micro-biological invaders. According to one researcher, inhaling traces of ozone causes the innate immune system to overreact, killing these key immune system cells, making the lungs more susceptible to subsequent invaders, such as bacteria. The researchers also found that the mice exposed to ozone had lower numbers of immune system cells circulating in the blood. In consideration of these studies, the EPA is currently in the final phases of reviewing and possibly updating the standards for allowable levels of ozone in the air (~60ppb?).