The Inherent Instability of Environmental Parameters Governing Indoor Air Quality on Board Ships and the Use of Temporal Trends to Identify Pollution Sources

Abstract

Indoor air quality on board a 36-year-old ship has been characterized at several locations. The ship is dedicated to nearshore operations at the Belgian coast. This paper presents time-averaged and continuous-time measurements of several indoor pollutant concentrations such as NO₂, O₃, NO, CO, total volatile organic compounds (TVOC), polycyclic aromatic hydrocarbons (PAH), particulate matter PM_2.5 and PM₁₀, black carbon, and individual organic compounds. Time-averaged measurements suggest that the ship’s indoor air quality is sufficiently safe according to the prescribed occupational and nonoccupational health limits. However, the concentration of some indoor pollutants is comparable to that of the outdoor air of a large city such as Brussels, Belgium. Continuous-time analyses show that the temporal trends of indoor pollutant concentrations are inherently unstable. A large number of peaks or valleys are observed on a slowly fluctuating background. At some occasions, pollutant concentrations exceed the nonoccupational thresholds. Several pollutant peaks occur simultaneously, resulting in a pattern of peaks that is typical for a pollution source (e.g., exhaust gases entering the ship’s castle through the ventilation inlet, human presence, and bunkering). This study illustrates that multiparameter monitoring campaigns give valuable information about the behaviour of pollution sources, facilitating the definition of mitigation actions.