The Delta OHM HD21ABE17 is a portable indoor air quality (IAQ) datalogger designed to monitor and analyse environmental conditions in various settings, including offices, schools, laboratories, and industrial environments. It simultaneously measures key parameters such as carbon dioxide (CO₂), carbon monoxide (CO), temperature, relative humidity, and atmospheric pressure. Additionally, it calculates derived metrics like dew point, wet bulb temperature, absolute humidity, mixing ratio, and enthalpy, providing a comprehensive assessment of indoor air quality.