The Washington Post

Don’t eat that snow!

- Ecology · Montreal · World Health Organization · U.S. Environmental Protection Agency · University of Saskatchewan · Arctic · Chemistry

In ur­ban ar­eas, the seem­ingly pure white stuff soaks up pol­lu­tants even as it falls.

You know the phrase “pure as driven snow”? Yeah, it’s en­tirely bunk. As much of the East Coast dug out from record-break­ing quan­ti­ties of the white stuff, the lat­est is­sue of the jour­nal En­vi­ron­men­tal Sci­ence: Pro­cesses & Im­pacts pub­lished a study show­ing that snow in ur­ban ar­eas soaks up toxic pol­lu­tants in the air, in­clud­ing can­cer-caus­ing chem­i­cals such as ben­zene.

“As a mother who is an at­mo­spheric phys­i­cal chemist, I def­i­nitely do not sug­gest my young kids eat snow in ur­ban ar­eas in gen­eral,” Parisa Ariya, a pro­fes­sor of chem­istry and at­mo­spheric sci­ences at Canada’s McGill Univer­sity in Mon­treal, told the Huff­in­g­ton Post.

Ariya’s re­search wasn’t pri­mar­ily fo­cused on snow as a gas­tro­nomic del­i­cacy. In­stead, she and her col­leagues were look­ing at how snow and cold in­ter­act with par­ti­cles in gaso­line ex­haust.

They found that snow acted like a sponge, ef­fi­ciently re­mov­ing ben­zene, toluene, xylenes and other chem­i­cals from the air.

Of course, all of those chem­i­cals then end up in the snow, where they make for a very un­sa­vory snack. Ben­zene, which is present in gaso­line, crude oil and cig­a­rette smoke, in­ter­feres with cell func­tions and can cause ane­mia, leukemia and other prob­lems, ac­cord­ing to the World Health Or­ga­ni­za­tion. The En­vi­ron­men­tal Pro­tec­tion Agency says that toluene, a gaso­line ad­di­tive, can dam­age the cen­tral ner­vous sys­tem, while xylenes are as­so­ci­ated with neu­ro­log­i­cal prob­lems, breath­ing dif­fi­cul­ties and kid­ney fail­ure, among other con­cerns.

“Th­ese find­ings demon­strate that the in­ter­ac­tion of gaso­line in­ter­nal com­bus­tion ex­haust with snow and the ef­fect of cold tem­per­a­ture have a po­ten­tial to in­flu­ence hu­man health and en­vi­ron­men­tal ef­fects as­so­ci­ated with ex­po­sure to ex­haust-de­rived air pol­lu­tion,” the study said.

It also warned that en­vi­ron­men­tal re­searchers should take into ac­count that the pres­ence of snow and cold might al­ter mea­sures of the amount of pol­lu­tants in the air.

If you re­ally have to eat snow — though we’re hav­ing trou­ble imag­in­ing a sit­u­a­tion in which this might be­come a con­cern — John Pomeroy, who stud­ies wa­ter re­sources and cli­mate change at the Univer­sity of Saskatchew­an, sug­gests wait­ing a few hours af­ter it be­gins to fall. Snow’s “scrub­bing brush” ef­fect on the at­mos­phere means that the air — and the snowflakes them­selves — get cleaner as a snow­storm goes on, Pomeroy told NPR’s “The Salt” last win­ter.

Most of the re­searchers “The Salt” spoke with said that toxin lev­els in snow are low enough that they would con­sider eat­ing it. And, as one should for a fine culi­nary treat, th­ese true snow con­nois­seurs knew how to sa­vor it.

“It is well known amongst snow chemists that fresh Arc­tic snow goes very well with 15-year-old sin­gle malt whiskey,” Pomeroy said.

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 ?? IS­TOCK­PHOTO ?? Ur­ban snowflakes soak up pol­lu­tants as they fall.
IS­TOCK­PHOTO Ur­ban snowflakes soak up pol­lu­tants as they fall.

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