This paper describes radon diagnostics and mitigation in a school the U.S. Environmental Protection Agency (EPA) classified "difficult to mitigate." The school had subslab utility tunnels that served as the outside air and return air mixing chamber for the heating and ventilation system. The heating and ventilation system depressurized the tunnel, sucked radon from the soil, and distributed it to school rooms. Extensive diagnostics were conducted to test mitigation options and to provide mitigation design parameters.

This study examines the use of energy recovery ventilators (ERV) in two schools located in a Southwestern arid climate as an energy-efficient means of providing acceptable ventilation to the classrooms and the corresponding effect on indoor air quality (IAQ) contaminant indicators. The effect of cleaning the existing systems· on thermal comfort conditions were also examined. IAQ measurements were made in selected classrooms with respect to carbon dioxide, viable and non-viable bioaerosols, volatile organic compounds, and respirable particles.

Mechanical ventilation systems, designed to meet ASHRAE's Standard 62-1989 and to modify building pressures, were installed in two New Mexico elementary schools to reduce elevated levels of indoor radon, carbon dioxide, and airborne particles. Although the systems did not meet design conditions for outdoor air delivery, ventilation rates were increased by factors of 2 to 4 over pre-existing natural ventilation rates, and levels of indoor air pollutants were significantly reduced.