The air is so polluted in this border city that residents can’t be outside and it hurts to breathe. There’s a city along the U.S.-Mexico border where the air is killing people. At least 78 people died of asthma and 903 people died of chronic obstructive pulmonary disease in the Mexicali area between 2010 and 2016, according to Mexican health records. Despite the deadly toll, government agencies have taken minimal steps to combat the pollution. Source 7y.