Accidental gassing incidents and the pulmonary function of pulp mill workers

A previous investigation of white male workers from a pulp and paper company in Berlin, New Hampshire identified decrements in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) associated with work in the pulping operations. A subset of those data were reanalyzed to consider another type of occupational exposure: gassing incidents in which workers were accidentally exposed to high levels of irritant gases, such as chlorine (Cl2) or sulfur dioxide (SO2). A total of 230 current and former workers (all white male) were included in the analysis. Gassing events were more common among pulp mill workers (34%) than workers from other parts of the company (9%). Average changes of -291.9 ml in FEV1 (p < 0.05) and -5.00% in FEV1/FVC (p < 0.05) were associated with gassing. Also, in each of the regression models for the three measures of pulmonary function (FEV1, FVC, and FEV1/FVC), there was a three-way interaction of cumulative smoking, cumulative pulp mill exposure, and gassing. The greatest decreases in FEV1 and FEV1/FVC associated with gassing were evident in the dual smoking/pulp mill exposure categories of none/high and high/none. The changes in pulmonary function appeared to be chronic effects that persisted beyond cessation of the exposure. Only limited information about the gassing episodes was requested from the subjects, and future research is discussed that will address some of the limitations.