Feb. 5, 2009 -- Poisonous ozone pollution is leaking across the borders of Canada and Mexico, and into the skies over parts of the United States, according to a new study. A major public health threat when left unchecked, surface-level ozone in the United States has been on decline in recent years, owing to tight pollution regulations put in place by the Environmental Protection Agency. In the past decade, nitrogen oxide emissions from power plants -- a prime ingredient in ozone formation -- have been cut in half. But new research published in the February issue of the journal Atmospheric Environment has found that significant plumes of the gas are wafting into the northeastern United States from Canada, and into Southern California from Mexico. On average, U.S. background ozone levels are between 25 and 30 parts per billion. Of that, Mexico and Canada's combined contribution is usually low, about three or four parts per billion. Related Content:
When researchers performed a computer simulation of ozone during the summer of 2001, though, they were surprised to find several days when Canadian pollution added 10 parts per billion of ozone -- and once up to 33 parts per billion -- to the air over parts of New York, New Jersey, Massachusetts, and several other northeastern states. "We often expect that air coming down from Canada is nice and clean, but it turns out that's not always the case," said Daniel Jacob of Harvard University, a co-author on the study. "And in a way it makes sense -- 75 percent of Canada's population lives within 100 miles of the U.S. border." Mexico contributed somewhat less to ozone over southern California, never getting above 18 parts per billion in a given day. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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