Jill M Ferdinands1
, Carol A Gotway Crawford2
, Roby Greenwald3
, David Van Sickle1,4
, Eric Hunter3
and W Gerald Teague3 
1
Air Pollution and Respiratory Health Branch, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS A-32, Atlanta GA 30333, USA
2
Office of Career and Workforce Development, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS E-94, Atlanta GA 30333, USA
3
Emory Pediatrics Asthma Research Center, Department of Pediatrics, Emory University, 2015 Uppergate Drive, Atlanta GA 30322, USA
4
Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, 610 Walnut St, 707 WARF, Madison, WI 53726, USA