smog index

例句：

1. 1. The city's smog index has been steadilyrising since last year.
   该市的烟雾指数自去年以来一直在稳步上升。
2. 2. Thegovernment is working on a plan to reducethe smog index in the city.
   政府正在制定一项计划，以减少该市的烟雾指数。
3. 3. The smogindex is a measure of air pollutionand can be used to predict health impacts.
   烟雾指数是衡量空气污染的一个指标，可以用来预测健康影响。