中文摘要
尽管有充分证据表明石油和天然气开发导致当地环境空气质量下降，但关于这些活动与人类健康之间存在因果联系的证据较少。本文探讨了原油开采期间燃烧天然气副产品——燃除——的环境健康成本。我们利用由风向模式与天然气处理能力交互作用产生的上风向燃除的准随机变异，估计了燃除天然气对呼吸系统健康的影响。具体而言，我们构建了一个新数据集，以与产能受限的天然气处理设施相连的上风向油气井数量作为月度上风向燃除的工具变量，估计了上风向燃除增加对月度呼吸系统相关就诊率的因果效应。我们发现，北达科他州燃除天然气数量增加1%将导致呼吸系统相关就诊率增加0.73%。此外，在样本期内，暴露于一半以上燃除天然气的邮政编码区仅提取了不到20%的资源财富，且暴露于不成比例燃除量的邮政编码区往往属于经济弱势群体和有色人种社区。我们的估计表明，健康成本构成了燃除外部成本的重要组成部分，因此在全球减少燃除的倡议中应予以考虑。
Abstract
Although there is strong evidence that oil and natural gas development lead to decreases in local ambient air quality, there is less evidence of a causal link between these activities and human health. This paper explores the environmental health costs of burning natural gas by-products during crude oil extraction – flaring. We estimate the impact of flared natural gas on respiratory health by using quasi-random variation in upwind flaring generated by the interaction of wind patterns and natural gas processing capacity. Specifically, we construct a novel dataset to estimate the causal effect of increased upwind flaring on the monthly respiratory-related hospital visitation rate by using the number of upwind wells that are connected to a capacity-constrained natural gas processing facility as an instrument for monthly upwind flaring. We find that a 1% increase in the amount of flared natural gas in North Dakota would increase the respiratory-related hospital visitation rate by 0.73%. Furthermore, zip codes that were exposed to more than half of all flared natural gas extracted less than 20% of all resource wealth during the sample time period, and the zip codes exposed to a disproportionate amount of flaring tend to be economically-disadvantaged and communities of color. Our estimates indicate that the health costs constitute a material portion of the external cost of flaring, and therefore ought to be considered in global initiatives to reduce flaring.