Indoor Air Quality in Inner-City Schools and its Associations with Building Characteristics and Environmental Factors

This field study characterizes indoor air quality (IAQ) across 16 public schools slated for major renovation in a high-poverty Mid-Atlantic U.S. city. Researchers measured PM2.5, NO₂, CO, CO₂, temperature and humidity in two classrooms and two common areas over three seasons, pairing 291 school-day observations with simultaneous outdoor sampling and more than 60 building, room and neighborhood variables. Average classroom ventilation was sub-standard: median CO₂ frequently exceeded the ASHRAE 1,000 ppm guideline, and 25 % of hourly indoor NO₂ readings surpassed WHO limits, especially in winter. Mixed-effects modeling showed the strongest IAQ predictors were outdoor traffic and industrial sources, but building factors also mattered: physical defects (leaky roofs, broken windows, cracked walls) and temporary structures elevated indoor NO₂ and CO, while rooms with air-conditioning or greater setback from the curb had lower concentrations. Higher floor levels and younger-grade classrooms carried greater PM2.5, suggesting resuspension and activity effects.

The authors conclude that deferred maintenance and aging infrastructure amplify pollution infiltration in inner-city schools, and that renovations targeting envelope integrity, HVAC upgrades and location siting could meaningfully reduce exposure and associated health risks for vulnerable student populations.