Analysis of CO₂ monitoring data demonstrates poor ventilation rates in Albanian schools during the cold season

Abstract

Poor ventilation in schools is associated with accumulation of indoor-generated pollutants, which is associated with “stuffy” air, elevated risk of infectious diseases and impaired learning outcomes. This survey in Albania was conducted as part of WHO’s efforts to facilitate assessments of indoor air quality and other environmental factors in schools in the European Region. The survey was conducted in 36 classrooms in 12 middle schools (eight urban and four rural) from December 2011 through March 2012. In each school, carbon dioxide (CO₂) was continuously measured in three classrooms during one school week. Ventilation rates during classes were estimated using the build-up and steady-state mass balance equations utilizing CO₂ concentration data, classroom occupancy and classroom volume. All 12 schools had gravimetric ventilation systems. Heating systems were absent or not operational in most schools. Average classroom temperatures during lessons varied from 9.1 to 14.4 °C (median 11.7 °C) with lower temperature associated with poorer ventilation. Weekly average CO₂ levels during classes ranged from 1286 to 5546 ppm (median 2776 ppm) while average ventilation rates ranged from 0.8 to 3.6 (median 1.8) litres per second per person. Classrooms with indoor combustion heaters had higher indoor temperature, lower CO₂ levels and higher levels of carbon monoxide (CO). WHO guidelines on 1- and 8-h CO exposure levels were exceeded in one classroom. Classroom CO₂ levels were substantially above and ventilation rates below existing national and international guidelines. Detrimental impacts of poor ventilation on health and learning outcomes are likely to be substantial in Albanian schools during the cold season. Indoor temperature in most classrooms was below the commonly recommended levels.