Proper levels can reduce the risk of stress fractures, inflammatory injuries and upper respiratory tract infections.

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It therefore appears to be an attractive alternative treatment for upper respiratory tract infections.

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They had had fewer upper respiratory tract infections by the age of one than the other group.

BBC: Doctors could predict which children are at risk of asthma

In 2003, during the severe acute respiratory syndrome epidemic, 76 percent of Hong Kong residents wore simple masks, and in this case, mask use was associated with a lower incidence of SARS, as well as upper respiratory tract infections and influenza.

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