Nitrogen Push Gas as Carbon Dioxide Exposure Control in Blended Beverage Manufacturing

Abstract

Carbon dioxide (CAS# 124-38-9) is a toxicant that causes metabolic stress as well as the more commonly known asphyxiation. Worker’s manufacturing and bottling beverages, including carbonated soft drinks, may be exposed to carbon dioxide. Controlling exposure to carbon dioxide in beverage manufacturing workers is primarily of health significance, because exposure to elevated carbon dioxide is associated with metabolic stress. This study investigates the exposure control efficacy of using nitrogen instead of carbon dioxide as a push gas for counterpressure beverage filling machines. This study examines non-dispersive infrared (NDIR) exposure monitoring data for carbon dioxide both before the exposure control intervention when carbon dioxide was used, and after nitrogen was used instead, as a naturally occurring field experiment. A comparison between conditions indicated that this method is both significant by Welch’s t-test (t = 6.6453, df = 14.935, p-value < 0.01), with a large effect size (Cohen’s d = 2.451221), and was also significant by Expostats Tool 1 (-2 AIHA Risk Band). The result of the push gas substitution was also sufficient to control previously unacceptable exposures below the occupational exposure limit (most likely AIHA Risk Band Category 2 (69.7%), < 5% Category 4). This study includes the presentation of 8-hour time-weighted average (TWA) exposure monitoring data, as well as the use of current statistical methods for exposure decision analysis (EDA). Based on this evaluation, using nitrogen as a push gas is an effective change to reduce worker exposure to carbon dioxide.