Descriptions of the ten WTC studies included in the meta-analysis.

Note: PTSD (%)  =  probable PTSD prevalence. n =  total numbers of participants. FDNY  = Fire Department of the City of New York. PCL = PTSD Checklist-Civilian Version, DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, 4th edition. a, PTSD assessed by a modified PCL. b1, those with PTSD alone; b2, those with both PTSD and lower respiratory symptoms. c, full PTSD. d, the percentages (%) of male sex and white ethnic/race, and age in years (age ± standard deviation, median, or age bracket with the largest percentage) were shown in (). d, results from 2006–2007 was used in this meta-analysis.