Ground-level ozone in the form of smog, shown here in Denver, can affect human health post wildfires, even if the smoke from fires is not visible. Credit: NREL A study that assesses the effects of wildfires over two decades shows that wildfire smoke significantly raises ground-level ozone and contributes to excess deaths from wildfire smoke in the United States each year. The research, led by Minghao Qiu, Ph.D., of Stony Brook University, is published in Science Advances . Why ozone from fires matters Previous research about wildfire smoke, its health risks, and impact on excess deaths, has largely overlooked ozone and concentrated more on dangerous particulates emitted from fires. Ozone is invisible, but it is a strong oxidant. When humans are exposed to more ozone it is linked to several health issues such as respiratory and cardiovascular problems, reduced cognitive performance, as well as increased mortality.…