VOA常速英语2019--空气污染导致儿童哮喘病例激增（在线收听）

We already know that traffic pollution is a big contributor to climate change, but new research suggests, it’s also a huge driver of health problems around the world. Recent estimates show that air pollution is actually the leading environmental health risk factor globally more than any other environmental cause of disease. According to the World Health Organization, air pollution causes an estimated 3.7 million premature deaths every year, but a new study from George Washington University in Washington DC points to a specific pollutant, nitrogen dioxide NO2, from car emissions as the leading cause of childhood asthma in many cities around the world. Nitrogen dioxide pollution has a really important impact on the number of children worldwide that are being diagnosed with asthma, and in fact the largest impacts were seen in cities where up to almost about 50 percent of new asthma cases among children, in some cities worldwide, were attributable to nitrogen dioxide pollution. And a really troubling element of the research, the cities where all this asthma is happening have levels of NO2 that are within limits considered safe by the World Health Organization.

我们都知道，交通污染是气候变化的主要原因之一，但新研究表明，交通污染还导致了全球各地的许多许多健康问题。最近的估测显示，空气污染实际上是全球范围内首要的健康威胁因素，甚于其他引发疾病的环境问题。根据世界卫生组织（WHO）的数据，空气污染每年引发近370万例早逝。但华盛顿特区乔治·华盛顿大学的一项新研究点名指出一种污染物——二氧化氮，这是一种汽车排放物，是世界许多城市出现儿童哮喘的主要原因。二氧化氮污染对于全球确诊为哮喘病的儿童数量有极为重大的影响。实际上，有些受到影响最大的城市甚至有近50%的新哮喘病例是出现在儿童身上的，而究其根源都是二氧化氮污染。该研究还有一项发现令人担忧：因二氧化氮而导致哮喘病例的城市，其二氧化氮水平在WHO认定的安全范围内。

One of the most surprising findings for us was that actually over 90 percent of annually pediatric asthma incidents occurred in areas that already met the World Health Organization guideline for annual average nitrogen dioxide pollution of 21 parts per billion. It’s not much of a surprise that most of the cities with the highest levels of NO2 pollution are in three countries, China, India and the United States. The solution these researchers say is to continue the fight against climate warming greenhouse gases because the two problems are so closely related. One of the things that we found in our study was that cities that had higher nitrogen dioxide levels also had higher greenhouse gases. And so one thing that can be done would be to avoid burning fossil fuels, and reduce it in any way we can. The researchers say they hope to do more studies to understand which specific chemicals in NO2 pollution trigger asthma, so they can help target those specific sources of emissions.

最让人吃惊的一项发现是：实际上，每年，90%以上的儿科哮喘病例所发生的地区都已经符合了WHO关于年平均二氧化氮排放的参考指数——十亿分之二十一。这些科学家表示，解决方式是继续抵制温室气体，因为这两个问题息息相关。我们研究还有一项发现：二氧化氮水平更高的城市，其温室气体含量也更高。所以，有一件事是我们可以做的，那就是加大力度避免并尽可能减少化石燃料的燃烧。这些科学家表示，他们希望做更多的研究来了解二氧化氮污染中有哪些具体的化学物质引发了哮喘病。这样他们就能助力对抗这种特定的汽车尾气排放物。