美国一半的空气污染死亡与州外排放有关

美国一半的空气污染死亡与州外排放有关

Over half the deaths due to poor air quality occurring in the U.S. are because of emissions from outside the state in which the deaths occur, according to a new study published in February 2020 in the journal Nature.

根据《自然》杂志在2020年2月发表的一项新研究，在美国，因空气质量差导致的死亡中，超过一半是由死亡发生地以外的州的排放造成的。

The study

研究

The tendency of air pollutants to cause death across national and international borders is well known.  Researcher Steve Barrett says, "It's been well known in Europe for over 30 years that power stations in England would create acid rain that would affect vegetation in Norway."

空气污染物跨越国家和国际边界造成死亡的趋势是众所周知的。研究员史蒂夫·巴雷特说:“30多年来，欧洲人都知道英国的发电站会产生酸雨，影响挪威的植被。”

On the other hand, a detailed and sequential account of this phenomenon especially with regard to human health has not yet been provided, and this motivated the current study.

另一方面，关于这一现象，特别是与人类健康有关的这一现象，尚未提供详细和有序的描述，这促使了目前的研究。

The researchers looked at the path followed by the emission of a range of air pollutants produced by combustion in various fields, over the period 2005 to 2018. They traced these emissions in every state, from one season to the next, and from one year to the following year.

研究人员观察了2005年至2018年期间各个领域燃烧产生的一系列空气污染物的排放路径。他们追踪了每个州的排放量，从一个季节到下一个季节，从一年到第二年。

The tool

研究工具

In the past, it has been difficult to calculate the effects of air pollutants produced in one state on the residents of another. The availability of modern computers and programs has facilitated this work in the current world. This means it is now possible to track the course of emissions from and to each state with respect to the remaining states rapidly and efficiently.

过去，很难计算一个州产生的空气污染物对另一个州居民的影响。现代计算机和程序的可获得性促进了当前世界的这项工作。这意味着现在可以快速有效地跟踪每个州相对于其余州的排放过程。

Barrett and his researchers produced such a computational tool inspired by the work of Daven Henze of the University of Colorado at Boulder. This helped them trace the effects of air pollution on health in each state. They looked at sulfur dioxide, ozone, fine particulate matter, and other pollutants from a host of emission sources at fixed intervals for each hour of each day over the whole year.

巴雷特和他的研究人员受科罗拉多大学博尔德分校的戴文·亨泽的工作启发，开发了这样一个计算工具。这有助于他们追踪每个州空气污染对健康的影响。他们观察了全年每天每小时固定间隔的二氧化硫、臭氧、细颗粒物和来自大量排放源的其他污染物。

The sources explored include electric power plants, road transport, ships, railways, airplanes, commercial and residential emissions. The emission data was collected in 2005. 2011 and 2018.

探索的污染源包括发电厂、公路运输、船舶、铁路、飞机、商业和居民排放。排放数据是在2005年、2011年和2018年收集的。

The researchers used the GEOS-Chem atmospheric chemistry model to tell them what became of these emissions at each season and each year. The path of these emissions was tracked based on the wind patterns, and the reactions of the chemicals in the pollutant to the air. They finally used a model derived from epidemiological data to measure the risk of early death due to the exposure of a population to those pollutants.

研究人员使用GEOS-Chem大气化学模型来告诉他们这些排放在每个季节和每年都会发生什么。这些排放的路径是根据风型和污染物中的化学物质对空气的反应来跟踪的。他们最终使用了一个从流行病学数据中得出的模型来衡量由于人群暴露在这些污染物中而导致的过早死亡风险。

This model is thus a matrix with many dimensions, and it shows how the emissions from any of these sectors from any state at any time, containing any pollutant, produces an impact on the health measures of another state. Says Barrett, "We can figure out, for example, how much NOx emissions from road transportation in Arizona in July affects human health in Texas, and we can do those calculations instantly."

因此，这个模型是一个多维矩阵，它显示了任一州在任何时间、包含任何污染物的任何这些部门的排放如何对另一个州的健康措施产生影响。巴雷特说：“例如，我们可以计算出亚利桑那州7月份道路运输产生的NOx排放量对德克萨斯州人类健康的影响，我们可以立即进行这些计算。”

The findings

结论

The study shows that of the air pollutants produced in one state, over 50 percent is carried through the air into other states. Thus, each state affects the quality of health of people living in other states and contributes to their risk of premature death. And it's not just states across the immediate border that are affected but even those farther away. Different emissions, says Barrett, travel different distances, but some effect states more than a thousand miles away from the state of origin.

研究表明，在一个州产生的空气污染物中，超过50%是通过空气进入其他州的。因此，每个州都会影响生活在其他州的人的健康质量，并增加他们过早死亡的风险。受影响的不只是直接边境的州，甚至是那些更远的州。巴雷特说，不同的排放物传播的距离不同，但有些效应表明距离发源地超过一千英里。

The highest risk of death due to emissions occur as a result of electric power generation. In 2005. sulfur dioxide emissions from power plant chimneys caused deaths in other states than the one in which the plant was located in 3 of 4 cases. However, since 2005 the number of early deaths due to air pollution has shown a significant downturn and was almost a third less in 2018. In concrete terms, this means about 30.000 people didn't die earlier than expected because of air pollution.

由于排放造成的死亡风险最高的原因是发电。2005年，发电厂烟囱排放的二氧化硫在电厂所在的州以外的其他州造成了4例死亡中的3例。然而，自2005年以来，因空气污染而过早死亡的人数出现了显著下降，2018年几乎减少了三分之一。具体地说，这意味着大约有3万人没有比预期更早地死于空气污染。

Moreover, the percentage of deaths due to out-of-state emissions is also declining, from about 53 percent in 2005 to about 41 percent in 2018. The reason may be stricter regulation of emissions from electric power plants. For instance, the Clean Air Act is a regulation passed by the Environmental Protection Agency (EPA), which is a chief contributor to reducing emissions from this sector, among other laws. Barrett says, "Regulators in the U.S. have done a pretty good job of hitting the most important thing first, which is power generation, by reducing sulfur dioxide emissions drastically, and there's been a huge improvement, as we see in the results."

此外，因州外排放造成的死亡比例也在下降，从2005年的约53%下降到2018年的约41%。原因可能是对发电厂排放的监管更加严格。例如，《清洁空气法》是美国环境保护局通过的一项法规，它是减少该部门排放的主要贡献者，以及其他法律。巴雷特说，“美国的监管机构通过大幅减少二氧化硫排放，在首先打击最重要的事情-发电方面做得相当好，正如我们在结果中看到的那样，已经有了巨大的改善。”

However, emissions from other sources are now on the rise, wafting across state lines to cause deaths in other locations. According to Barrett, vehicles, industrial emissions, and residential emissions are now areas of concern.

然而，来自其他来源的排放现在正在上升，飘过州界在其他地方造成死亡。根据巴雷特的说法，车辆、工业排放和居民排放现在是令人担忧的领域。

The implications

影响

Barrett says their team has set up a massive database for use by people concerned with public health. He concludes, "We think there are a lot of things that policymakers can dig into, to chart a path to saving the most lives."

巴雷特说，他们的团队已经建立了一个庞大的数据库，供关注公共卫生的人使用。他总结道，“我们认为政策制定者可以深入研究很多东西，以规划出一条拯救最多生命的道路。”