Air Pollution According to an Air Quality Management District, the level of nitrogen dioxide, a brown gas that impairs breathing, present in the atmosphere on a certain May day in a busy downtown city is approximated by A(t) = 0.03t (t - 7)4 + 61.9 (0 s ts 7) where A(t) is measured in pollutant standard index (PSI) and t is measured in hours, with t = 0 corresponding to 7 a.m. At what time of day is the air pollution increasing, and at what time is it decreasing? (Enter your answers using interval notation in terms of t. ) increasing decreasing Need Help? Read It Watch It