EVALUATION OF INDOOR AND OUTDOOR AIR-QUALITY OF A NURSERY-SCHOOL IN MEXICO-CITY

Objective, To evaluate the differences between indoor and outdoor ozon e (O-3) and nitrogen dioxide (NO2) levels at a school located in south west Mexico City. Material and methods. Indoor and outdoor O-3 and NO2 levels were measured dairy between January and April 1990 by manual m onitoring. Results, Indoor and outdoor concentrations of nitrogen diox ide did not surpass the Mexican standard (0.21 ppm). The correlation c oefficient between maximum NO2 concentrations measured by the city's l ocal monitoring station and those measured outside the classroom was 0 .82 (p < 0.001). Regarding ozone, its maximum outdoor concentration wa s 0.29 ppm and indoor concentrations were on average below 0.06 ppm (m aximum=0.17 ppm). The indoor/outdoor correlation coefficient was 0.72, and for every 1.7 ppm outside, there was 1.0 ppm inside (p < 0.05) Co nclusions, Since the highest outdoors O-3 concentrations were observed between 11:00 and 14:00 hrs, it is recommendable to have recess befor e this time.