2015 No https://doi.org/10.1111/ina.12136 Muscatiello, N. North America Experimental Exposure Study Teachers Elementary (K-5) Middle/Jr High (6-8) High School (9-12) Carbon Dioxide (CO2) Headaches Other Teachers School health Carbon dioxide (CO2) Indoor environmental quality CO2 was measured in 64 classrooms across 10 NY schools; teacher symptoms were linked to CO₂ levels. Neuro-physiologic symptoms rose with every 100 ppm increase. Classroom-specific ventilation corrections may improve staff health and indoor air quality.