The respiratory pyramid: From symptoms to disease in World Trade Center exposed firefighters


  • Role of Authors: Mr. Niles had full access to all of the data in the study and takes full responsibility for the integrity of all the data and the accuracy of the data analysis. Mr. Niles, Dr. Webber, and Dr. Prezant contributed to the origination of the study, analysis of data and drafting of the manuscript. Ms. Ye, Ms. Zeig-Owens, Ms. Glaser, and Ms. Weakley contributed to preparation and analysis of data, and editing the manuscript. Dr. Cohen and Dr. Hall provided statistical expertise, analysis of data and editing of the manuscript. Dr. Weiden, Dr. Aldrich, Dr. Kelly, Ms. Glass and Dr. Nolan, provided conceptual advice and edited the final manuscript.
  • Disclosure Statement: The authors report no conflicts of interests.

Department of Epidemiology and Population Health, Montefiore Medical Center/Albert Einstein College of Medicine and Director of WTC Epidemiology, Bureau of Health Services, Fire Department of the City of New York, Brooklyn, NY.




This study utilizes a four-level pyramid framework to understand the relationship between symptom reports and/or abnormal pulmonary function and diagnoses of airway diseases (AD), including asthma, recurrent bronchitis and COPD/emphysema in WTC-exposed firefighters. We compare the distribution of pyramid levels at two time-points: by 9/11/2005 and by 9/11/2010.


We studied 6,931 WTC-exposed FDNY firefighters who completed a monitoring exam during the early period and at least two additional follow-up exams 9/11/2005–9/11/2010.


By 9/11/2005 the pyramid structure was as follows: 4,039 (58.3%) in Level 1, no respiratory evaluation or treatment; 1,608 (23.2%) in Level 2, evaluation or treatment without AD diagnosis; 1,005 (14.5%) in Level 3, a single AD diagnosis (asthma, emphysema/COPD, or recurrent bronchitis); 279 (4.0%) in Level 4, asthma and another AD. By 9/11/2010, the pyramid distribution changed considerably, with Level 1 decreasing to 2,612 (37.7% of the cohort), and Levels 3 (N = 1,530) and 4 (N = 796) increasing to 22.1% and 11.5% of the cohort, respectively. Symptoms, spirometry measurements and healthcare utilization were associated with higher pyramid levels.


Respiratory diagnoses, even four years after a major inhalation event, are not the only drivers of future healthcare utilization. Symptoms and abnormal FEV-1 values must also be considered if clinicians and healthcare administrators are to accurately anticipate future treatment needs, years after initial exposure. Am. J. Ind. Med. 56:870–880, 2013. © 2013 Wiley Periodicals, Inc.