美国城市空气污染最严重
最近的一份报告追踪了2018年全球城市和国家的空气污染水平。
虽然与印度和中国等最严重的罪犯相比，美国表现良好，但美国一些城市的空气质量仍然很差。
由于野火，加利福尼亚州的主要城市在2018年的污染水平特别高，
Sacramento had the worst air pollution of any major city on earth in November.
Los Angeles is also struggling to recover from the California wildfire season.
In 2018, San Francisco’s air quality reached levels that could cause coughing and irritation.
San Diego’s air quality earned an ‘F’ letter grade.
Cincinnati, Ohio suffers from particle pollution, which is often produced by construction sites and automobiles.
Coal-fired power plants spell bad news for air quality in Indianapolis, Indiana.
Pittsburgh, Pennsylvania was just shy of WHO’s clean air threshold.
Traffic congestion in Boston, Massachusetts could be polluting the air.
Business Insider