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This paper is a case study of ventilation and indoor air quality (IAQ) investigations in an extensively repaired comprehensive school in Finland. Our main hypothesis is that positive pressure between air indoors and outdoors can be used for decreasing the concentration of harmful chemical and microbiological agents in indoor air, as well as occupants' complaints about IAQ, in a building waiting for new repairs or with unsolved IAQ problems. Research was undertaken on a building consisting of 12 classrooms, and served by one air handling unit. It found that the ventilation system was crucially unbalanced. However, IAQ measurements did not explain occupants' symptoms, which were suspected to be related to the impurities leaked through the building envelope caused by the high negative pressure. To eliminate the potential harmful effects of the building related sources and infiltration airflows, the air handling unit was adjusted to generate a 5-7 Pa positive pressure for a period of 4 months. In the next planned phase of the study, moisture content of the structures during the heating season will be measured, as well as potential changes in perceived IAQ and microbial contamination. [ABSTRACT FROM AUTHOR]

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• Indoor air quality (IAQ) of schools with/without reported IAQ complaints were studied. • Indoor climate questionnaires were used to verify the categorisation of schools. • More cultivable airborne microbes were found in schools with reported IAQ complaints. • Trichoderma was found only in the schools with reported IAQ complaints. • Other IAQ-related measurements were unable to uncover reasons for IAQ complaints. Reported indoor air quality (IAQ) complaints are common even in relatively new or renovated school buildings in Finland. However, detecting the causes for complaints with commonly used indoor air measurements is difficult. This study presents data on perceived and measured IAQ in six comprehensive school buildings in Finland. The aim of this study was to discover the possible differences of perceived and measured IAQ between schools with reported IAQ complaints and schools without reported IAQ complaints. The initial categorisation of schools with ('problematic schools') and without ('comparison schools') complaints was ensured via a validated indoor climate survey and a recently developed online questionnaire, which were completed by 186 teachers and 1268 students from the six schools. IAQ measurements of physical parameters, gaseous pollutants, particulate matter and bioaerosols were conducted in four problematic school buildings (26 classrooms) and two comparison school buildings (12 classrooms). Using air sampling as well as exhaust air filters and classroom settled dust to detect the presence of elevated concentrations of airborne cultivable microbes and pathogenic, toxigenic and mycoparasitic Trichoderma strains were the most indicative methods in distinguishing problematic schools from comparison schools. Other IAQ-related measurements did not detect clear differences between problematic and comparison schools, as the concentration levels were very low. The results indicate that the complaints reported by occupants could have been related to excess moisture or mould problems that had not been found or repaired. Ventilation pressure condition investigations and simultaneous exhaust and supply air filter dust culture should be addressed precisely in future studies. [ABSTRACT FROM AUTHOR]

Numerous studies show that landscape simplification reduces abundance and diversity of natural enemies in agroecosystems, but its effect on natural pest control remains poorly quantified. Further, natural enemy impacts on pest populations have usually been estimated for a limited number of taxa and have not considered interactions among predator species. In a quantitative synthesis with data collected from several cropping systems in Europe and North America, we analyzed how the level and within-field spatial stability of natural pest control services was related to the simplification of the surrounding landscape. All studies used aphids as a model species and exclusion cages to measure aphid pest control. Landscape simplification was quantified by the proportion of cultivated land within a 1 km radius around each plot. We found a consistent negative effect of landscape simplification on the level of natural pest control, despite interactions among enemies. Average level of pest control was 46% lower in homogeneous landscapes dominated by cultivated land, as compared with more complex landscapes. Landscape simplification did not affect the amount of positive or negative interactions among ground-dwelling and vegetation-dwelling predators, or the within-field stability of pest control. Our synthesis demonstrates that agricultural intensification through landscape simplification has negative effects on the level of natural pest control with important implications for management to maintain and enhance ecosystem services in agricultural landscapes. Specifically, preserving and restoring semi-natural habitats emerges as a fundamental first step to maintain and enhance pest control services provided by predatory arthropods to agriculture. [ABSTRACT FROM AUTHOR]