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To study the combined effect of different environmental factors on children in a classroom setting, 250 children from seven primary schools were exposed to 36 different environmental configurations (‘all’ and ‘fewer’ acoustical panels; ‘displacement’ and ‘mixing’ ventilation; sound type: ‘children talk’, ‘traffic’, and ‘none’; and ‘direct’, ‘indirect’ and ‘soft’ lighting). In a four-way factorial design, they assessed with 18 groups on eight different days temperature, draught, noise, light and smell. Correlation, three-way ANOVA, comparison tests and multi-regression analysis were used to analyse relationships, and main, cross-modal and interaction effects. The results show that more acoustical panels had a positive effect on the children’s assessment of sound. Sound type had a main effect on the assessment of sound. Statistical significant cross-modal effects were found for lighting and sound type on the assessment of smell. Significant three-way interactions between ‘Vent’, ‘Sound’, and ‘Light’ types were found for smell and light in the ‘fewer panels’ situations; and for light in the ‘all panels’ situations. Multiple-regression analysis also showed that perception of smell was significantly related with draught, sound and light perception in ‘fewer panels’ conditions. Further studies on these cross-modal interactions are recommended, specifically at individual level.

BackgroundWhile the indoor environmental quality of classrooms is a potential issue because it may affect the wellbeing of school children, the relations are still poorly studied. This study aimed to investigate the relations between classroom characteristics and health and comfort of school children.Material and methodsA questionnaire was distributed among 1311 school children (8–12 years old, average 10) of 54 classrooms at 21 schools in The Netherlands. Additionally, the survey included an inspection of the school and its installations and an inspection of the classrooms surveyed using checklists, and monitoring of some environmental parameters (temperature, relative humidity and CO2 concentration) in the classrooms.ResultsAmong the children studied, 87% was bothered by noise, 63% by smells, 42% by sunlight when shining, 35% didn't like the temperature in the classroom (too cold or too warm) and 34% experienced temperature changes. Main diseases reported comprised of allergies (26%), rhinitis (17%), hay fever (16%) and eczema (16%). Health and comfort in non-traditional schools was better than in the traditional schools studied (A non-traditional school is a school in which the way of educating children is different from the traditional way of education, according to a different educational theory). Physical building characteristics of the classrooms studied in the traditional schools were associated with the Classroom Symptom Index (location of school building, heating system, solar devices hampering opening windows or ventilation) and the Classroom Comfort Index (ventilation type, window frame colour, floor material and vacuum cleaning frequency).ConclusionsMeasures to improve acoustical, air, and thermal conditions of children in classrooms are needed. More research is required on the use of different lighting systems and use of different colours in classrooms.

Literature shows that both building systems and occupants’ behaviour contribute to the amount of energy used to create a comfortable indoor environment. To determine possible relationships, energy consumption of nine school buildings was studied in relation to identified building characteristics, self-reported frequency of teachers’ actions, and (perceived and measured) indoor environmental quality (IEQ) of the school children in the classrooms studied. These schools were located in different areas in the Netherlands, and their yearly energy consumption differed a lot. Results demonstrated significant relationships of electrical energy consumption with lighting distribution in classrooms and the frequency of teachers’ light switch behaviour: the higher the measured illuminance in the classrooms, the more electricity was used in the school building. The more electricity was used, the more children complained about the IEQ in their classrooms; and the more frequently the teachers turned on the light, the less electricity the schools consumed. It was concluded that stimulating teachers to be more active in controlling the light might lead to energy saving, but a larger sample of schools with more variation in buildings systems is required to confirm this.

The study of protective film formation on Mg alloys by exposure to sodium selenite solutions was conducted. Anodic polarization studies, electrochemical impedance spectroscopy studies, morphological analysis, and Energy-dispersive X-ray spectroscopy were performed on AZ31 Mg alloy after coating treatment in different concentrations of sodium selenite. The corrosion resistance was improved by around 5 times compared with control. Improved resistance to localized corrosion was observed in the coatings treated by 5 mM or 10 mM sodium selenite. The protection mechanism was ascribed to the transformation of selenite to insoluble selenium, the formation of insoluble MgSeO3 hydrate, and polymerization of amorphous selenium.

High efficiency air filtration has been suggested to reduce airborne transmission of ‘infectious’ aerosols. In this study the ‘air cleaning’ effect as well as the effect on sound and air velocity (draught risk) of a mobile High-Efficiency Particulate Air (HEPA) filter system was tested for different settings and positions in the Experience room of the SenseLab. From both the noise assessments by a panel of subjects and sound monitoring it was concluded that the mobile HEPA filter system causes an unacceptable background sound level in the tested classroom setting (Experience room). With respect to the air velocity measurements and draught rating calculations, it was concluded that both depend on the position and the setting of the HEPA filter system as well as on the position and height of the measurements. For the removal of aerosols simulated by air-filled soap bubbles in front of the subject, the mobile HEPA filter system performed better as compared to the ‘No ventilation’ regime, for all settings and both positions, and for some settings, even better than all the tested mixing ventilation regimes. The use of a mobile HEPA filter system seems a good additional measure when only natural ventilation options are available. Future research should focus on rooms of different sizes or shapes, as this may also play a role in the filter's performance, noise and draught effects., Highlights • A mobile HEPA filter system is a good additional measure to natural ventilation. • The mobile system can result in unacceptable noise levels and draught effects. • The HEPA filter's cleaning performance depends on setting and position in a room.

Indoor environmental quality (IEQ) in classrooms can have an effect on school children’s comfort, health, and performance. In most classrooms, the teacher is the only one who can take actions to change the IEQ. The objective of this study was to identify what teachers usually do to improve IEQ in classrooms and how these actions relate to children’s comfort perceptions. A survey was carried out among 1145 school children (9–12 years) in 21 primary schools (54 classrooms) in the Netherlands. Every child filled out a questionnaire about their comfort perception and every teacher filled out a questionnaire about their IEQ-improving actions and school children’s requests to change the IEQ. The relations among children’s comfort perceptions, their requests, and teachers’ actions were analysed through t-tests and chi-squared tests. The most common action conducted by teachers was opening windows because of the ‘too warm’ complaints. Correspondingly, the most frequent request of the children was opening/closing windows because of thermal discomfort. However, the teachers’ actions did not have a significant impact on children’s comfort perceptions, which means that teachers could not fulfil every child’s needs in a classroom, even though teachers’ actions did relate to the child’s requests.