HealthDay News: Breathing polluted air for even two hours can boost blood pressure, potentially raising the risk of cardiovascular disease in those exposed to smog, a new study suggests. Although the increase may not mean much for healthy people, “this small increase may actually be able to a trigger a heart attack or stroke,” study author Dr. Robert D. Brook, an assistant professor of medicine at the University of Michigan, said in a university news release. An estimated nearly one in three …