题目中已经说明了However, since the rate of deaths due to asthma has increased dramatically even in cities with long-standing, comprehensive medical records and with little or no urban pollution,就是说,即使没什么环境污染,患者人数也增多,你就不要考虑环境问题了. C是解释那个inhaler怎么干坏事的.即使污染没增加,它使肺更容易受影响,也会增加肺病概率 | 
