A Comparison of Relative Humidity between Two Swedish Buildings with Different Ventilation Solutions

This project is based on measurements of the parameter relative humidity, RH (%), in two buildings: one with natural ventilation and one with mechanical ventilation. Both buildings are located in central Sweden, which constitutes a representative climate zone with respect to Swedish conditions. An important factor for the indoor environment, which affects human health and well-being, is the level of the relative humidity, RH (%). Research studies show that the healthiest level should be in the range of 40% - 60%. Surveys have revealed that about 70% of the employees at Swedish offices, schools and kindergartens experience that the air is too dry during the winter season. Previous studies show that the level of relative humidity in the indoor environment influences the prevalence of respiratory infections and allergies. The purpose of this study is to investigate how the relative humidity differ between the two buildings, and if this may be a cause of the health problems that users are affected by. During many years, users have complained about the environment in the building with mechanical ventilation and that they suffer from health problems. The method used in the study is air measurements of the two parameters, relative humidity and air temperature in the two buildings using data loggers. The indoor environment is affected by the outdoor climate and therefore instruments are placed outdoors to record seasonal variations. The measurements were carried out during the period October 2014 to September 2015 to include all of Sweden’s four seasons with completely different climatic conditions. The results of this study show that the relative humidity in the mechanically ventilated building is consistently significantly lower than in the building with natural ventilation whatever the time of year and temperature indoors. This study shows that mechanical ventilation in buildings affects the indoor environment negatively with respect to human health during most time of the year and this fact must be taken into consideration for the existing as well as the planning of new ventilation systems.

Assessing Occupational Exposure to Surface Contaminants in Kuwaiti Educational Buildings

The prevalence of surface contaminants,such as potentially harmful bacteria,within building environments in the State of Kuwait is not known.To the authors’knowledge,this article is the first of such a report.A total of 342 stool samples were collected from 46 secondary schools to evaluate indoor occurrences of E.coli bacteria within selected lavatory surfaces.After microbiological testing,the results for the spread of the E.coli bacteria were categorized by total count,sampling location dependency,contamination level comparison between genders,and lavatory fixtures(i.e.seat and squat toilets).The results revealed that 7 schools have a bacterial contamination problem,there is cross-contamination between surfaces in the lavatory stalls,the boys’lavatories were less sanitary than the girls’,and that the squat-style toilets are more contaminated than the seat-style.The results suggest that there is significant risk of spread of bacterial infection among students via contaminated hands and surfaces in the lavatory area in some schools.Thus,this study emphasizes the need to improve environmental hygiene and enhanced sanitation in these schools.In addition,conclusions can be drawn as to the effectiveness of the janitorial staff employed by the schools and the efficacy of the cleaning regime used in the lavatories.Furthermore,based on the findings,there are architectural design consequences as squat-style toilets might be excluded in lavatories designed for schools to be constructed in the future.

Determining indoor air quality and identifying the origin of odour episodes in indoor environments

A methodology for identifying volatile organic compounds （VOCs） and determining air quality of indoor air has been developed. The air samples are collected using pump samplers by the inhabitants when they perceive odorous and/or discomfort episodes. Glass multi-sorbent tubes are connected to the pump samplers for the retention of VOC. The analysis is performed by automatic thermal desorption （ATD） coupled with gas chromatography-mass spectrometry （GC/MS）. This methodology can be applied in cases of sick building syndrome （SBS） evaluation, in which building occupants experience a series of varied symptoms that appear to be linked to time spent in the building. Chemical pollutants concentrations （e.g., VOC） have been described to contribute to SBS. To exemplify the methodology, a qualitative determination and an evaluation of existing VOC were performed in a dwelling where the occupants experienced the SBS symptoms. Higher total VOC （TVOC） levels were detected during episodes in indoor air （1.33 ±1.53 mg/m^3） compared to outdoor air （0.71± 0.46 mg/m^3）. The concentrations of individual VOCs, such as ethanol, acetone, isopropanol, 1-butanol, acetic acid, acetonitrile and 1-methoxy-2-propanol, were also higher than the expected for a standard dwelling. The external source of VOC was found to be an undeclared activity of storage and manipulation of solvents located at the bottom of a contiguous building.

Indoor microbiome and allergic diseases:From theoretical advances to prevention strategies

The prevalence of allergic diseases,such as asthma,rhinitis,eczema,and sick building syndrome(SBS),has increased drastically in the past few decades.Current medications can only relieve the symptoms but not cure these diseases whose development is suggested to be greatly impacted by the indoor microbiome.However,no study comprehensively summarizes the progress and general rules in the field,impeding subsequent translational application.To close knowledge gaps between theoretical research and practical application,we conducted a comprehensive literature review to summarize the epidemiological,environmental,and molecular evidence of indoor microbiome studies.Epidemiological evidence shows that the potential protective indoor microorganisms for asthma are mainly from the phyla Actinobacteria and Proteobacteria,and the risk microorganisms are mainly from Bacilli,Clostridia,and Bacteroidia.Due to extremely high microbial diversity and geographic variation,different health-associated species/genera are detected in different regions.Compared with indoor microbial composition,indoor metabolites show more consistent associations with health,including microbial volatile organic compounds(MVOCs),lipopolysaccharides(LPS),indole derivatives,and flavonoids.Therefore,indoor metabolites could be a better indicator than indoor microbial taxa for environmental assessments and health outcome prediction.The interaction between the indoor microbiome and environmental characteristics(surrounding greenness,relative humidity,building confinement,and CO_(2) concentration)and immunology effects of indoor microorganisms(inflammatory cytokines and pattern recognition receptors)are briefly reviewed to provide new insights for disease prevention and treatment.Widely used tools in indoor microbiome studies are introduced to facilitate standard practice and the precise identification of health-related targets.