The strategy might even prove productive if action is taken in the waning days of the Obama administration, which has expressed concern not only about toxic pollutants like sulfur dioxide that can be particularly harmful to people with asthma or other breathing problems, but carbon dioxide and other greenhouse gases that contribute to climate change. Maryland is imperiled by all of the above and needs federal authorities to act given that as much as 70 percent of the state's air pollution can be traced to upwind sources.