title: Respiratory Health Effects of Ultrafine Particles in Children: A Literature Review.
abstract: By convention, airborne particles ≤0.1 μm (100 nm) are defined as ultrafine particles (UFPs). UFPs can comprise a large number of particles in particulate matter with aerodynamic diameters ≤2.5 μm (PM2.5). Despite the documented respiratory health effects of PM2.5and concerns that UFPs might be more toxic than larger particular matter, the effects of UFPs on the respiratory system are not well-described. Even less is known about the respiratory health effects of UFPs among particularly vulnerable populations including children. We reviewed studies examining respiratory health effects of UFPs in children and identified 12 relevant articles. Most (8/12) studies measured UFP exposure using central ambient monitors, and we found substantial heterogeneity in UFP definitions and study designs. No long-term studies were identified. In single pollutant models, UFPs were associated with incident wheezing, current asthma, lower spirometric values, and asthma-related emergency department visits among children. Also, higher exhaled nitric oxide levels were positively correlated with UFP dose among children with asthma or allergy to house dust mites in 1 study. Multivariate models accounting for potential co-pollutant confounding yielded no statistically significant results. Although evidence for a relationship between UFPs and children's respiratory is accumulating, the literature remains inconclusive. Interpretation of existing data is constrained by study heterogeneity, limited accounting for UFP spatial variation, and lack of significant findings from multi-pollutant models.
authors.affiliation: Department of Medicine, University of California, San Francisco, 505 Parnassus Ave, Moffitt Room 987, San Francisco, CA, 94143, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Heinzerling
authors.affiliation: Epidemic Intelligence Service, Office of Public Health Scientific Services, Centers for Disease Control and Prevention, 4770 Buford Highway, Mailstop F-60, Atlanta, GA, 30341, USA.
authors.forename: Joy
authors.initials: J
authors.lastname: Hsu
authors.affiliation: Air Pollution and Respiratory Health Branch, Division of Environmental Hazards and Health Effects, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway, Mailstop F-60, Atlanta, GA, 30341, USA.
authors.forename: Fuyuen
authors.initials: F
authors.lastname: Yip
keywords: child; particulate matter; respiratory health; ultrafine