Clean Identification? The Effects of the Clean Air Act on Air Pollution, Exposure Disparities, and House Prices
评估了美国《清洁空气法》对PM2.5的影响，发现2005年法规五年内降低了0.4 μg/m³，且对污染较重地区效果更大；同时缩小了城乡和黑白人群的暴露差距，但房价中体现的污染损害比以往估计更大。
We assess the US Clean Air Act standards for fine particulate matter (PM 2.5 ). Using high-resolution data, we find that the 2005 regulation reduced PM 2.5 levels by 0.4 μg/m 3 over five years, with larger effects in more polluted areas. Standard difference-in-differences overstates these effects by a factor of three because time trends differ by baseline pollution, a bias we overcome with three alternative approaches. We show that the regulation contributed to narrowing Urban-Rural and Black-White PM 2.5 exposure disparities, but less than difference-in-differences suggest. Pollution damages capitalized into house prices, however, appear larger than previously thought when leveraging regulatory variation.