Indoor air quality in Portuguese schools: levels and sources of pollutants

Abstract

Indoor air quality (IAQ) parameters in 73 primary classrooms in Porto were examined for the purpose of assessing levels of volatile organic compounds (VOCs), aldehydes, particulate matter, ventilation rates and bioaerosols within and between schools, and potential sources. Levels of VOCs, aldehydes, PM 2.5 , PM 10 , bacteria and fungi, carbon dioxide (CO 2 ), carbon monoxide, temperature and relative humidity were measured indoors and outdoors and a walkthrough survey was performed concurrently. Ventilation rates were derived from CO 2 and occupancy data. Concentrations of CO 2 exceeding 1000 ppm were often encountered, indicating poor ventilation. Most VOCs had low concentrations (median of individual species <5 lg/m 3 ) and were below the respective WHO guidelines. Concentrations of particulate matter and culturable bacteria were frequently higher than guidelines/reference values. The variability of VOCs, aldehydes, bioaerosol concentrations, and CO 2 levels between schools exceeded the variability within schools. These findings indicate that IAQ problems may persist in classrooms where pollutant sources exist and classrooms are poorly ventilated; source control strategies (related to building location, occupant behavior, maintenance/cleaning activities) are deemed to be the most reliable for the prevention of adverse health consequences in children in schools. Practical ImplicationsThis study provides quantitative assessment for a large set of indoor air quality (IAQ) parameters in public primary classrooms together with information regarding potential building-wide contamination sources. Elevated levels of CO 2 , PM 2.5 , PM 10 and bacteria may be associated with outdoor pollution sources, occupant behavior, maintenance/ cleaning activities and poor ventilation. IAQ investigations often include air sampling, which must be carefully conducted if representative data are to be collected. To better understand sampling results, investigators need to account for the variability of contaminants both within and between schools. These findings are of relevance to public health due to the very large population of exposed school children, especially since attendance in primary schools is compulsory and asthma and allergy are very common diseases in childhood. These data may be useful for assessing health effects of exposure, for understanding the underlying mechanisms and for implementing preventive policies in terms of standards and guidelines.

Building characteristics, indoor environmental quality, and mathematics achievement in Finnish elementary schools

“…multi-pollutant assessment to thoroughly characterize IAQ in schools, which would improve understanding of the children's exposure to indoor air pollutants and the most effective means to reduce these exposures. Such studies have also been useful in terms of developing strategies (such as source control) for preventing adverse health consequences for children in schools [41,42].…”

Source apportionment of CO2, PM10 and VOCs levels and health risk assessment in naturally ventilated primary schools in Porto, Portugal

“…As children spend most of their time in an indoor environment, it is clear why indoor air quality (IAQ) has been recognised as one of the key influences on their health. The classrooms are one of the main places where children spend their time when they are not at home [7,8]. Air quality inside classrooms has been associated to several diseases common in childhood, such as asthma, rhinitis and rhinoconjunctivitis [9e11].…”

“…Each indoor school environment has unique characteristics determined by the local outdoor air, specific building relatedcharacteristics, such as the condition, maintenance, and cleaning of the school building, and occupant behaviour [8,13]. The pollutants in the air within a classroom are predominantly the same of the outdoor air when the latter comes in though natural ventilation and infiltration.…”

Ability to Determine the Quality of Indoor Air in Classrooms without Sensors

“…Many studies are carried out in schools, because children are more sensitive for inadequate indoor air quality and they spend most of their day-time in classrooms. Children are particularly susceptible to indoor air pollution when compared to adults due to their underdeveloped immune and respiratory systems and high inhalation rates per body mass [1]. One of the first extensive studies to investigate indoor air quality in schools was carried out in Stockholm (Sweden) by Elias Heyman in the XIX century and the results were not satisfactory [2].…”

“…Now, many research in schools indicates that the problem of inappropriate indoor air quality still exists and it is spread around the world in developing and developed countries. For example in schools in Portugal [1], Japan [3], and Denmark [4]. In all of the works, authors claims that one of the problems is inefficient natural ventilation, which consists buoyancy-driven ventilation and ability of opening windows.…”