一项新研究考察了空气污染及其对美国过早死亡的影响。过早死亡是指在平均死亡年龄之前发生的死亡。
Researchers found that half of all such deaths related to air pollution resulted from pollution that came from another state.
研究人员发现，在空气污染相关死亡中，有一半以上是由于其它州的污染造成的。
The study is the first to estimate how pollution crossing state lines affects early deaths, says Steven Barrett. He is a professor at the Massachusetts Institute of Technology and a co-writer of a report on the study.
史蒂文·巴雷特表示，这是第一项评估跨州污染如何影响过早死亡的研究。巴雷特是麻省理工学院的教授，也是这项研究报告的合著者。
Worldwide, an estimated 4.2 million premature deaths are linked to outdoor air pollution. Most of those deaths are from heart disease, stroke and lung disease, as well as acute breathing infections in children, reports the World Health Organization.
在全球范围内，估计有420万例过早死亡与室外空气污染有关。世界卫生组织报道称，其中多数死亡是由于心脏病、中风、肺部疾病以及儿童急性呼吸道感染。
Efforts to deal with outdoor air pollution have largely centered on relationships between local sources of pollution and local air quality. But Barrett and other researchers found that, in the United States, cross-state pollution is a major concern.
室外空气污染的应对措施主要围绕当地污染源与当地空气质量之间的关系。但是巴雷特和其他研究人员发现，在美国，跨州污染是一个主要问题。
"Pollution is even less local than we thought," Barrett said.
巴雷特表示：“污染甚至比我们想象的要更少来自于本地。”
The computer model his team developed for the study looked at the atmospheric chemistry processes and weather conditions over an 11-year period. It then tied that information to information on human exposures and health risks.
他的团队为这项研究开发的计算机模型研究了11年期间的大气化学过程和天气状况。然后将这些信息与人类暴露和健康风险的信息联系到一起。
The researchers then examined how each of the lower 48 states affects pollution and people's health in every other state.
研究人员随后研究了美国本土48个州中的每个州如何影响其它各州的空气污染和居民健康状况。
The model included records from 2005, 2011 and 2018 on different sources and kinds of pollutants. The pollution came from seven producers of emissions, including electric power stations, road transportation, shipping, railroads and airplanes.
该模型包含了2005年、2011年和2018年不同种类和来源的污染物记录。这些污染来自于7个排放源，包括发电厂、公路运输、航运、铁路和飞机。
The team found that electric power plants -- which release sulfur dioxide -- were the biggest contributor to deaths related to pollution from other states. In 2005, sulfur dioxide from power plants was involved in 75 percent of cases of premature deaths from out-of-state pollutants.
该研究小组发现，释放二氧化硫的发电厂是造成其它州与污染相关死亡的最大原因。2005年，来自于发电厂的二氧化硫牵涉到75%的州外污染物导致的过早死亡案例。
Net exporters and net importers
净输出州和净输入州
Not all states contribute to the problem equally, the study showed. Many states in the northern, middle part of the country, such as North Dakota, are "net exporters" of pollution-related health effects. That is in part because of their low populations in comparison to the amount of pollution they create.
研究表明，并非所有州都要对该问题负有同等责任。美国北部和中部的许多州，例如北达科他州，都是污染相关健康影响的净输出州。部分原因是与它所造成的污染量相比，它们的人口少。
Many states on the east coast are "net importers" of air pollution. New York is hit especially hard, with 60 percent of early deaths related to air pollution coming from out-of-state emissions.
东海岸的许多州都是空气污染的净输入州。纽约州受到的影响尤为严重，该州60%的过早死亡都跟外州排放导致的空气污染有关。
Doctor Peter Muennig studies health effects of air pollution at Columbia University's Mailman School of Public Health in New York City. He praised the new research.
彼得·缪尼格博士在纽约市哥伦比亚大学梅曼公共卫生学院研究空气污染对健康的影响。他盛赞了这项新研究。
"This is a great study," said Muennig, who was not involved in the research.
并未参与这项研究的缪尼格表示：“这是一项伟大的研究。”
A notable limit, he said, is that the information is based on models, which can be complex and more likely to contain mistakes.
他说，一项值得注意的局限在于这些信息是基于模型，而模型可能会很复杂，也很可能包含错误。
Barrett said the researchers tried to measure areas of uncertainty in the models.
巴雷特表示，研究人员试图测量了模型中不确定因素。
He said, "Like with climate change, not knowing the exact number doesn't mean you don't take action, because uncertainty cuts both ways and reality could be worse than our central estimates, as well as better."
他说：“像气候变化一样，不知道确切数字并不意味着毫不作为，因为不确定性是把双刃剑，现实可能会比我们预计要更差，也可能会更好。”
Barrett added that the team has a large amount of data that policymakers could use to try to lower the number of deaths.
巴雷特还表示，该团队拥有大量数据，决策者可以利用这些数据来降低死亡人数。
The study was published this month in Nature.
该研究发表在本月的《自然》杂志上。
I'm Ashley Thompson.
我是阿什利·汤普森。(51VOA.COM原创翻译，禁止转载，违者必究！)