Exposure assessment of potash miners at elevated CO2 levels

In a potash mine in the center of Germany, stationary measurements 40 cm above ground level have revealed occasional increases in the carbon dioxide (CO2) levels that exceed the 0.5 vol.% German occupational exposure limit (OEL). This study, therefore, aimed to examine the individual exposures of potash miners to CO2 at their underground workplaces.

119 miners were equipped with personal CO2 detectors to log the individual CO2 exposures during underground work. We decided to use electrochemical monitors due to their compactness and minimal mass. Furthermore, generated CO2 measurements with precipitated overshooting and false positive CO2 values were studied using diverse CO2 test gases and different fumigation times.

The personal detectors showed short-term CO2 peak exposures at very high concentrations in a limited number of workers. Twenty-two threshold limit value violations were observed according to the present OEL, and the personal CO2 monitoring allowed categorization into three exposure groups, low (n = 83), moderate (n = 26) and high burdens (n = 10) of CO2.

The electrochemical sensors used have numerous properties that can potentially influence the assessment of exposures. The current findings suggest that assessing similar exposure scenarios, with respect to elevated and strongly fluctuating CO2 concentrations, the behavior of electrochemical sensors should be taken into consideration.