Pollution of the past may have been even worse than we knew

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By Globe Staff 

1,347: That’s how many dead birds, stored at natural history museums, were examined to determine how much soot was on their feathers when they died. The results showed how much black carbon was in the air during different time periods when the amount of industrial air pollution was at its worst. The study, published in the Proceedings of the National Academy of Sciences, focused on the industrial belt stretching from New Jersey through Michigan. The findings show that air pollution may have been far worse than previously thought — meaning that US cities once looked a lot like modern day Beijing or Delhi.