It is a complicated matter mapping the movement of pollution in the atmosphere, but Noelle Eckley Selin models not just the chemistry of the atmosphere as it absorbs emissions and responds to climate change, but its potential impact over time on human health and world economies. She takes a systems approach “to understanding how past, present and future human activities influence pollution, and its impact.” Her goal: to provide good science for policy decisions.  Selin notes the dominating contribution of motor vehicles to air pollution. Something like 56% of nitrous oxides (NOx) flow from cars and trucks, and more from construction, lawn and garden equipment. These gases form smog and ozone, which constitute a major threat to human health, in the form of increased cases of asthma and cardiovascular disease, she says. The EPA has “ratcheted down” its allowance of permissible NOx emissions, and for particulates, but, Selin says, recent health research “suggests there is no threshold for ozone damages beyond background level.” Pollution impact of these gases is a moving target not just in health research, but also around climate change, where ozone and particulates are known “climate forcers.” However, says Selin, the feedbacks between climate and emissions are quite complicated, and “a policy win on climate doesn’t necessarily mean a win on air pollution.” To help achieve “win-win scenarios” addressing both air pollution and climate, Selin and her colleagues are hard at work on a battery of studies that couple methodologies, modeling air pollution impacts on the economy (“looking at how economic activities and choices influence pollution controls;” projecting health effects of ozone and particulates concentrations in 16 global regions; and the negative economic impacts resulting from pollution related health issues. Unlike other work that focuses on running scenarios focused on single topics, Selin says, “We’re taking multiple models, to give more of a r...