Hazardous atmospheres in confined spaces may be obvious when a source of air contamination or oxygen (O2) deficiency is recognized. Such is often the case in general industry settings, especially with work processes which create hazardous atmospheres that may be anticipated. Hazards present in active sewers are also well recognized; but the possibility that O2 deficiency or high airborne contaminant concentrations may exist in new construction sewers or storm drains has been repeatedly ignored with deadly results. Low O2 and high carbon dioxide (CO2) concentrations may exist in new construction manholes that have not yet been connected to an active sewer or drain system, and these concentrations have been shown to vary over time. A recent incident is described where workers repeatedly entered such a confined space without incident, but subsequent entry resulted in a fatality and a near-miss for a co-worker rescuer. Additional cases are discussed, with an emphasis placed on elevated CO2 concentrations as a causative factor. A description is provided for the adsorptive gas chromatography whole-air analysis methodology used to quantitatively determine atmospheric conditions present at this type of fatality site or others after an incident, and for the gas chromatography-mass spectrometry method used to provide confirmation of analyte identity with high certainty. Many types of confined spaces may be encountered in addition to the underground varieties discussed, and many possible atmospheric hazards are possible. The definitive whole-air analysis approach described here may be of use and should be considered to investigate many confined space fatality and near-miss cases, and to better understand the causes of dangerous atmosphere conditions that may arise in confined spaces.
Keywords: Confined space; carbon dioxide; new-construction manhole; whole-air composition analysis.