The WTC collapse created a disaster site with WTC-derived pollutants that were highest during the collapse and then gradually dissipated (1
). Adequate respiratory protection was not immediately available (3
), and many rescue workers and residents have respiratory symptoms and physiologic airway abnormalities (4
). This study demonstrates substantial reductions in average adjusted FEV1
and FVC in FDNY rescue workers during the year after 09/11/2001. In addition, WTC exposure intensity, assessed by arrival time or work assignment, predicted further pulmonary function loss and respiratory symptoms. WTC exposure had clinically and statistically significant effects on pulmonary function after 09/11/2001; we observed a reduction in average adjusted FEV1
that was equal in magnitude to 12 yr of aging-related FEV1
decline in this cohort. The validity of these findings is strongly supported by large cohort size (n = 12,079) and availability of almost 5 yr of preexposure spirometries.
The WTC plume was most intense on Day 1 and then dissipated, with marked reduction after it rained on 09/14/2001 (1
). This environmental measure of airborne WTC pollutant intensity corresponds well with the arrival time–based linear exposure intensity–response gradient observed. More than 400 chemicals have been identified in WTC-derived airborne pollution (1
). Induced sputum from FDNY firefighters and cellular and animal models all demonstrate inflammation (21
). Resulting clinical (cough, wheeze, dyspnea, chest tightness, gastroesophageal reflux) and physiologic (low FEV1
and FVC, bronchodilator response, nonspecific hyperreactivity) correlates have been reported in smaller occupational (3
) and community-based cohorts (4
) during the first year after 09/11/2001.
In contrast to our current study, prior WTC-related reports (3
) have been limited by (1
) cross-sectional design, (2
) small sample sizes, or (3
) lack of objective lung function documentation before the WTC exposure. Our study analyzed spirometric measurements for 83% of all FDNY rescue workers and included all measurements in a 6-yr longitudinal design. The 17% of workers who did not contribute spirometric measurements were significantly older, and more often nonwhite and female with longer FDNY tenure and EMS assignment. We observed a sizable spirometric loss of 372 ml when adjusted average FEV1
during the first year after 09/11/2001 was compared with the same measure during the preceding 5 yr. Although there is evidence for abnormal spirometry (25
), airway inflammation (27
), or hyperreactivity (28
) in case series and smaller cohorts after irritant exposures, there are only occasional reports that describe changes in such parameters from before to after an exposure for more than a few persons (30
). The largest relevant non-WTC study reported FEV1
decrements as large as 130 ml during a fire season in 52 wildland firefighters (32
). In a prior stratified sample of 319 WTC-exposed FDNY firefighters, we reported a mean FEV1
reduction of 264 ml from the last measurement before to the first measurement after 09/11/2001 (3
In addition to the substantial loss of average adjusted FEV1
for all WTC-exposed FDNY rescue workers, further WTC exposure intensity–related (arrival time– or work assignment–based) average adjusted FEV1
decrements were also evident. The earlier a worker arrived at the WTC site, the greater the spirometric reduction. Although the arrival time–based exposure intensity–response gradient in our cohort was statistically significant, it was rather small. Several factors likely reduced this gradient's magnitude. Most important, the amount of WTC exposure in the late-arrival group was heterogeneous, because this group included any worker who arrived after the first 48 h. Because most FDNY rescue workers arrived within the first 48 h, and because later arrival times were more prone to recall bias, we did not further partition the arrival time–based exposure categorization. Second, there was no adjustment for cumulative exposure because official work records are incomplete, and cumulative work hours are more difficult to remember than initial arrival time. Third, even with identical arrival and cumulative work times, large individual differences in airway deposition may have existed because of physiologic variations in minute ventilation, body habitus–related differences in airway branching angles (33
), and spatial and temporal heterogeneity of airborne substance concentrations (34
Work assignment–based WTC exposure intensity was an alternative predictor of additional spirometric loss, with firefighters experiencing larger decrements than EMS workers. This was likely caused by higher intensity WTC exposure associated with fire suppression or rescue activities as opposed to emergency medical tasks. In contrast to the pronounced influence of arrival time and work assignment, respiratory protective equipment had no appreciable effect on spirometric reductions after 09/11/2001. Initial lack of adequate equipment and subsequent compliance problems (3
) diminished any protective impact.
In the current study, we describe spirometric reductions in the FDNY cohort during the subacute period after 09/11/2001, with a median time of 3 mo between 09/11/2001 and a worker's first spirometry afterward, and with 90% of the cohort assessed during the first 5 mo after 09/11/2001. Potential pathogenetic mechanisms for these subacute spirometric decrements include airway inflammation and remodeling (6
). Our findings that hyperreactivity persisted 2 yr after 09/11/2001 in a smaller FDNY rescue worker cohort may be a sign of persistent inflammation or early remodeling (37
). The current investigation does not address how long-term spirometric changes will evolve in the entire WTC-exposed FDNY cohort. Prior longitudinal investigations have shown nonlinear patterns, with slowing of spirometric decrease after cessation of inhaled irritant exposure (38
) and during antiinflammatory treatment (39
). Long-term spirometric patterns for the FDNY cohort will undoubtedly be influenced by genetics, new inhaled irritant exposures, and treatment.
In summary, we demonstrated significant, clinically important, detrimental effects of WTC exposure on respiratory health during the first year after 09/11/2001 in WTC-exposed FDNY rescue workers. The FDNY cohort experienced the most intense WTC exposure and is the only group with preexposure spirometry available for systematic comparison. Findings should be extrapolated with caution to other, less exposed populations, but because even our least exposed group showed spirometric reductions after 09/11/2001, continued medical monitoring is prudent for all exposed populations. In addition to future spirometric surveillance, screening for physiologic or biochemical conditions associated with accelerated spirometric decline (40
) may help to identify subgroups with greater likelihood for airway disease development or progression in this high-risk setting.