阅读 ｜ 吃雪安全吗？真相是……

From little flurries to full-scale blizzards, it’s not unusual for snow to fall come winter. During the cold weather months, some folks like to share recipes for how to make snow ice cream and other treats that use fresh powder as a base, adding milk, sugar, and toppings.

从小雪花到暴风雪，冬天总要下几场雪的。在寒冷的日子里，有些人喜欢分享用雪做冰淇淋和其他甜点的食谱，在新鲜的雪中加入牛奶、糖，撒上浇头。

Obviously, no one is recommending anyone scoop up a bowlful of snow idling on the side of the road, full of salt, muck, and other unpleasantness. But it does beg the question: Is any snow actually safe to consume?

显然，没有人会建议你从马路边舀一碗雪来做美食，那里的雪掺杂着盐粒和淤泥，还有其他恶心的东西。但是这也引发了一个问题：有没有可以安心食用的雪？

While you may assume snow that’s freshly fallen and collected in an undisturbed area—even a cup set out for that purpose—is free of any contaminants, don’t be so sure. According to meteorologist Mary Scarzello Fairbanks, snow isn’t all that pristine. It’s formed when water droplets freeze around some dust or debris in the air, forming an ice crystal that continues to collect water vapor and form a snowflake.

你可能认为雪是从天上刚落下的，而且是在一个不受打扰的地方收集到的，甚至可能直接落入一个事先放好的杯子里，用这里的雪应该是没有任何污染的吧？不要那么肯定。气象学家玛丽·斯卡泽罗·费尔班克斯表示，雪并没有那么干净。雪是水珠与空气中的尘埃或碎片相结合后凝结而成的冰晶，在下落过程中继续吸收水蒸汽，多个冰晶聚集在一起就形成了雪花。

When it falls, it will also collect things hanging in the air, including dirt, soot, and even bacterial particles. Depending on the region, snow could also contain sulfates, nitrates, formaldehyde, mercury, or pesticides. If it’s windy, snow could even mix with dirt kicked up from the soil before settling. A 2015 study published in the journal Environmental Science: Processes & Impacts even demonstrated how snow could mix with gasoline exhaust. This all means that, theoretically, your snow ice cream could have some pretty disgusting “toppings.”

当雪花落下时，还会吸收空气中的悬浮物，包括灰尘、煤烟甚至细菌。有些地区的雪可能还会含有硫化物、硝酸盐、甲醛、水银或杀虫剂。如果风大的话，雪花甚至会与从泥地上扬起的尘土混合在一起。2015年发表在期刊《环境科学：过程与影响》上的一篇研究报告证实，雪中甚至会混入汽油车排放物。这一切都意味着，从理论上来说，你的鲜雪冰淇淋可能会包含一些相当恶心的“浇头”。

At the same time, there doesn’t seem to be a surge of reports of illnesses related to snow consumption. Assuming you don’t consume a huge quantity of it, it’s unlikely that whatever contaminants might be in the snow will be present in large enough amounts to cause problems. While no one is technically advocating for snow ingestion here, just a small bite will probably be fine.

与此同时，关于吃雪引发的疾病似乎没有太多报道。只要你不吃太多雪，雪中可能包含的任何污染物都不足以致病。严格意义上，我们并不建议你吃雪，但是吃一小口应该也无妨。

Eating snow in an emergency is another matter. The Centers for Disease Control and Prevention (CDC) warns against snow snacking for anyone stranded, such as hikers, because it can lower one’s body temperature. In cases where there is a water supply issue, the CDC says it’s safe to take collected snow and boil it to kill off any germs.

在紧急情况下吃雪则是另外一回事。美国疾病控制和预防中心警告任何陷入困境的人（比如徒步旅行者）不要吃雪，因为吃雪会降低体温。美疾控中心指出，在缺水的情况下可以收集干净的雪将其煮沸，杀灭细菌后再喝，这样才安全。