Is smaller worse? New insights about associations of PM

Little is known about PMA total of 59,754 children, aged 2-17 years, were recruited from 94 kindergartens, elementary and middle schools in the Seven Northeast Cities (SNEC) study, during 2012-2013. We obtained information on asthma and asthma-related symptoms including wheeze, persistent phlegm, and persistent cough using a standardized questionnaire developed by the American Thoracic Society. PMOdds ratios (ORs) of doctor-diagnosed asthma associated with a 10-μg/mThis study indicated that long-term exposure to PM