Indoor Air Pollution in Schools
Children are the most precious asset of a nation and are also the most vulnerable to the menace of environmental pollution. There exists a great number of studies signifying IAQ problems in schools mostly concentrating on a few specific pollutants, thermal conditions of school buildings, and overall comfort levels (Pegas et al., 2011). This multidisciplinary indoor air pollution research covers a wide range of pollutants and physio-chemical parameters including comfort signals and has realistic significance from the public health point of view. Locations, design parameters, and occupation density of schools are almost similar in major parts of the world. The gravity of the problems and the monitored values of the multiple parameters as found in this study would be more or less similar in other places as well. This study evidently provides at least two takeaway points for the global community with regard to schools − 1) providing adequate ventilation for better health of school children; 2) not permitting new schools adjacent to high traffic roads.
Yes, this study fills the inadequacies of erstwhile studies and appears to be multidisciplinary research covering multiple pollutants and comfort parameters. It also innovatively substantiates the findings with I/O ratios not attempted much so far.
From the practical point of view, the study methodology is commensurate with the required outputs, the number of sampling locations/sites, and the multiple parameters it attempted to monitor within a short span of time. However, I would also go for online real-time NOx monitoring.
The results of this study provide a good base for looking at IAQ in schools from a broader perspective. With regard to comfort parameters, results indicate that the mean daily temperature and mean daily RH values varied between 21.9 ± 1.09º C to 25.9 ± 1.56º C and 34.6 ± 3.49% to 56.2 ± 3.28% respectively. The temperature and RH variation intervals were 18.6º C – 22.2 º C and 25.1- 66.8% respectively. The comfort zone for temperature in winter is 22-23º C and in summer is 23-26 º C whereas the RH comfort zone is 30-60%. Almost in all schools, the temperature and RH were found to be within the recommended ranges. This finding is in line with expectation however, it might be different in highly humid parts like India and other South-Asian countries. CO2 levels were found to be higher than the prescribed level of 1800 mg/m3 indicating an inadequate air exchange rate inside the classrooms which is also in expected lines. Most classrooms do not meet the minimum ventilation rate of 2.5 l/s per person as stipulated by ANSI/ASHRAE (ANSI/ASHRAE Standard 55–2004, 2004). This study finds a linear correlation between CO and CO2. The station adjacent to the road showed higher CO as expected on account of vehicular traffic. Taking into account the CO levels recorded by the three monitoring stations close to the three main schools, mean I/O ratios close to zero were obtained. The highest CO levels were registered in the school located near one of the busiest streets of Lisbon. In all schools, the total fungal and total bacterial colony-forming units in both indoor and outdoor air were above the AMV of 500 CFU/m3 defined by Portuguese legislation (RSECE, 2006). Higher levels of bacteria can be attributed to higher occupancy, inadequate ventilation rate, and use of food products (Scheff, Paulius, Curtis, & Conroy, 2009). Benzene concentrations were also found higher for all indoor environments, ranging from 0.2 to a maximum of 0.9 LG/m3. Ingress of outdoor vehicular emissions, vinyl flooring, and paints might be the main sources of aromatics like benzene. Expectedly, schools located nearby busy streets recorded higher outdoor NO2 than indoor NO2.
Children of a nation studying in crowded schools located adjacent to main roads might end up growing as wasted talents and might even catch up with cardiovascular diseases. Thus, the school environment is an important aspect of nation-building. The two reasonable actions I would pinpoint are:
- Provide adequate ventilation in schools for better development of mind and body of the children;
- Do not permit any schools to come up in crowded areas adjacent to high-traffic roads.
ANSI/ASHRAE Standard 55–2004. (2004). Thermal environmental conditions for human occupancy. Atlanta, GA: American society of heating, refrigerating and air-conditioning engineers, Inc.
Pegas, P. N., Alves, C. A., Evtyugina, M. G., Nunes, T., Cerqueira, M., Franchi, M., & Freitas, M. C. (2011). Indoor air quality in elementary schools of Lisbon in spring. Environmental Geochemistry and Health, 33(5), 455-468.
RSECE (2006). Regulations on HVAC Systems in Buildings. Web.
Scheff, P., Paulius, V., Curtis, L., & Conroy, L. (2000), Indoor air quality in middle school. Part II: development of emission factors for particulate matter and bioaerosols. Applied Occupational and Environmental Hygiene 43, 298.