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This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original DOI.
Distribution of valid FEV1 diurnal variabilitya and lowest daily FEV1a values (mean ± SD) over the six seasonal assessment periods by at-risk status determined by seasonal diary (winter 2001 through spring 2002).