concerns grew about the health consequences of exposures sustained by persons involved in the rescue and recovery response. In addition to the estimated 10,000 Fire Department of New York (FDNY) personnel, an estimated 30,000 other workers and volunteers potentially were exposed to numerous psychological stressors, environmental toxins, and other physical hazards.

These concerns prompted CDC's National Institute for Occupational Safety and Health (NIOSH) to support the WTC Worker and Volunteer Medical Screening Program, which provided free, standardized medical assessments, clinical referrals, and occupational health education for workers and volunteers exposed to hazards during the WTC rescue and recovery effort. During July 16, 2002--August 6, 2004, the program evaluated 11,768 non-FDNY workers and volunteers. This report summarizes data analyzed from a subset of 1,138 of the 11,768 participants evaluated at Mount Sinai School of Medicine during July 16--December 31, 2002.

These data indicated that a substantial proportion of participants experienced new-onset or worsened preexisting lower and upper respiratory symptoms, with frequent persistence of symptoms for months after their WTC response work stopped. These findings underscore the need for comprehensive health assessment and treatment for workers and volunteers participating in rescue and recovery efforts.

The clinical program included a single screening evaluation consisting of medical- and exposure-assessment questionnaires, physical examination, pre- and post-bronchodilator (BD) spirometry, complete blood count, blood chemistries, urinalysis, chest radiograph, and mental health screening questionnaires. Participants were recruited through outreach that included community and union meetings, mailings, and articles in the media.

Eligibility for the screening program was based on arrival date and duration of exposure to the site* rather than on symptomatology. Institutional review board approval and informed consent were obtained for data aggregation and analyses.

The subset of 1,138 program participants was predominantly male (91%) and non-Hispanic white (58%), with a median age of 41 years (range: 21--74 years). Non-Hispanic blacks and Hispanics accounted for 11% and 15% of the population, respectively. The largest occupational sectors represented in this sample were technical and utilities (25%), law enforcement (21%), and construction (18%). Numerous other occupational groups accounted for the remaining 36%; 89% were union members.

Of the 1,138 participants, 525 (46%) worked on WTC rescue and recovery efforts on September 11, 2001, and 963 (84%) worked or volunteered during September 11--14, when exposures were greatest. During that period, a total of 239 (21%) participants reported using appropriate respiratory protection (i.e., full- or half-face respirators) (1). The median length of time worked on the WTC effort was 966 hours (range 24--4,080 hours). Of the 610 examinees present in lower Manhattan on September 11, a total of 313 (51%) reported being directly in the cloud of dust created by the collapse of the WTC buildings, and an additional 191 (31%) reported exposure to substantial amounts of dust.

A participant was considered to have a WTC-related symptom if the symptom either first developed (incident) or worsened (exacerbated) while working or volunteering on the WTC effort. WTC-related lower respiratory symptoms were reported by 682 (60%) of the sample, and 836 (74%) reported WTC-related upper respiratory symptoms. A total of 450 (40%) examinees had WTC-incident lower respiratory symptoms that persisted to the month before screening, and 565 (50%) reported WTC-incident and persistent upper respiratory symptoms (Table 1). Among the 851 participants who reported persistent WTC-related symptoms, an average of 32 weeks (range: 7--63 weeks) had elapsed since either they stopped working at the site or since the end of May 2002, when site cleanup was officially completed†. On examination, 527 (46%) had nasal mucosal inflammation. Other respiratory abnormalities (e.g., abnormal nasal turbinates or sinuses, rhonchi, and wheezing) were less common.

All participants underwent spirometry before and after an inhaled BD using standard techniques (2). A total of 360 (33%) participants had abnormal spirometry findings (Table 2), primarily because of results suggesting restriction; 84 (23%) had a significant§ post-BD response. A total of 22 (27%) of those with airway obstruction had a significant BD response consistent with asthma.

Compared with a general population sample of employed, adult, white males (National Health and Nutrition Examination Surveys [NHANES III]) (3), the 599 participants who had never smoked had a higher prevalence of abnormalities on spirometry (31% versus 13%), which was attributable to a higher prevalence of restriction (21% versus 4%).

Participants experienced numerous other symptoms (Table 3), including a substantial proportion with incident and persistent musculoskeletal symptoms, such as low back pain (16%) and upper or lower extremity pain (16% and 13%, respectively). Other incident and persistent symptoms included heartburn (15%), eye irritation (14%), and frequent headache (13%). Overall, 364 (23%) of the sample reported previously receiving medical care for WTC-related respiratory conditions. A total of 214 (19%) of examinees reported missing work because of WTC-related health problems (median: 10 days; range: 1--364 days).