Bronchial Reactivity and Lung Function After World Trade Center Exposure

Area of Science:

• Occupational Medicine
• Pulmonary Medicine
• Environmental Health

Background:

• World Trade Center (WTC) rescue workers experienced significant respiratory insult from inhaled WTC dust and gases.
• This exposure led to respiratory symptoms, reduced lung function, and often bronchial hyperreactivity (BHR).
• While respiratory issues persist, the long-term presence of BHR in WTC-exposed individuals remains understudied.

Purpose of the Study:

• To investigate the persistence of bronchial hyperreactivity (BHR) in World Trade Center (WTC)-exposed firefighters.
• To determine the association between persistent BHR and lung function decline (FEV1) over time.
• To evaluate the impact of corticosteroid treatment on lung function in this cohort.

Main Methods:

• A cohort of 173 WTC-exposed firefighters with baseline BHR measurements (within 2 years post-9/11) underwent follow-up testing in 2013-2014.
• Methacholine challenge tests were used to assess bronchial reactivity at baseline and follow-up.
• Forced expiratory volume in 1 second (FEV1) was measured across different time points, alongside recording of respiratory symptoms and corticosteroid use.

Main Results:

• Bronchial reactivity remained stable for 58% of participants.
• 57% of those with baseline BHR still exhibited BHR at follow-up; 19% of those without baseline BHR developed it.
• Baseline BHR strongly predicted follow-up BHR (OR, 6.46), and follow-up BHR was associated with a greater annual FEV1 decline (15.4 mL/y).
• Corticosteroid use was found to moderate the annual FEV1 decline.

Conclusions:

• Persistent BHR is a significant factor in the ongoing respiratory disease among WTC-exposed workers, likely driven by airway inflammation.
• Early and regular pulmonary function testing, including bronchial reactivity assessments, is crucial for managing occupational respiratory exposures.
• Inhaled corticosteroid therapy should be considered for individuals with symptoms or abnormal pulmonary function tests indicative of airway disease following massive occupational exposures.