[1
]US Environmental Protection Agency, Chapel Hill, North Carolina 27599, United States
[2
]Physician
Assistant Program, Methodist University, Fayetteville, North Carolina 28311,
United States
[3
]The
Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611,
United States
[4
]Section of Pulmonary and Critical Care and Lung Injury Center, Department of Medicine,
Chicago, Illinois 60637, United States