To Örebro University

Metals and metalloids are ubiquitously found in indoor environments due to their high crustal and soil abundance as well as their usage as different additives in materials. However, their presence in indoor environments is of high concern because they are nondegradable and some may be toxic, causing adverse health effects in occupants, especially children. In this study, 19 metals and metalloids were measured in indoor dust samples collected from 26 preschools in December 2023 (winter) to investigate their potential indoor sources and exposure risks. Among the 19 elements, 18 were detected in one or more of the participating preschools, while 13 were detected in all preschools. The detected indoor dust concentrations were in general lower compared to other studies possibly due to different exposure patterns such as the location of the preschools, indoor settings, and interior decorations as well as sampling techniques. Furthermore, the results revealed that the indoor dust concentrations of several metals could be attributed to anthropogenic sources due to high enrichment factors (EFs). The statistical tests (Student ' s t-test and Pearson ' s correlation coefficient) further identified the following potential indoor sources: Manganese (Mn) concentrations were linked to usage of foam mattresses, while dust concentrations of Mn, iron (Fe), cobalt (Co), and lead (Pb) were linked to usage of wallpaper. Antimony (Sb) posed the largest non-carcinogenic exposure risk, with hazard indexes at 0.14 and 0.34 calculated from the median value and 95th percentile, respectively. In addition, total chromium (Crtot), nickel (Ni), and arsenic (As) showed potential carcinogenic risks. The result from this study offers valuable insights into potential sources of indoor contamination sources and associated exposure risks, which can be used to identify preventive measures to reduce children ' s exposure during preschool attendance.

Brominated flame retardants (BFRs) and organophosphate esters (OPEs) are added to various products to gain specific properties such as reduced flammability and increased flexibility, which has resulted in constant, but usually slow, emission of these compounds to indoor environments. Many BFRs and OPEs are persistent, bioaccumulative and toxic, and have often been detected in indoor dust. This has raised concerns because indoor dust has been identified as one of the major non-dietary exposure pathways for children. In this study, 26 BFRs and OPEs were measured in indoor dust samples collected from 26 preschools in Sweden to identify potential indoor contamination sources and estimate the exposure risk of the detected levels. Among the targeted OPEs, tris(2-butoxyethyl) phosphate (TBOEP) was detected in all the preschools, with a mean concentration of 610 mu g/ g. Among the BFRs, decabromodiphenyl ether (BDE-209) was the predominant compound, with a mean concentration of 130 ng/g, even though it is globally regulated. Triphenyl phosphate (TPHP) was significant higher in preschools built before 2014. Also, 2-ethylhexyl diphenyl phosphate (EHDP) and BDE-209 were significant higher in preschools with sound boards on the walls and without wallpaper, respectively. Furthermore, in three of the participating preschools, an increase in total OPEs was observed between the years 2015 and 2023, possibly due to constant release of the targeted compounds and introduction of new and recycled products. Although the detected indoor dust levels showed a low exposure risk, levels of TBOEP were found to significantly contribute to the chemical burden of children attending the preschools.

The use of an airtight frame in low-energy buildings could increase the risk of health-related problems, such as allergies and sick building syndromes (SBS), associated with chemical emissions from building materials, especially if the ventilation system is not functioning properly. In this study, the indoor air quality (IAQ) was investigated in newly built low-energy and conventional preschools by monitoring the indoor air temperature, relative humidity, particle-size distribution and levels of carbon dioxide (CO2), nitrogen dioxide (NO2), formaldehyde and total volatile organic compounds (TVOC). The thermal comfort was satisfactory in all preschools, with average indoor air temperature and a relative humidity at 21.4C and 36%, respectively. The highest levels of TVOC (range: 130–1650 mg/m3 toluene equivalents) and formaldehyde (range: 1.9–28.8 mg/m3) occurred during the first sampling period associated with strong emissions from building materials. However, those preschools constructed with environmental friendly building materials (such as Swan Eco-label) had lower initial TVOC levels compared to those preschools constructed with conventional building materials. The IAQ and indoor chemical emissions were also strongly dependent on the functioning of the ventilation system. Preliminary risk assessment indicated that exposure to acrolein and crotonaldehyde might lead to respiratory-tract irritation among occupants.

The envelope of low-energy buildings is generally constructed with significant amounts of plastics, sealants and insulation materials that are known to contain various chemical additives to improve specific functionalities. A commonly used group of additives are flame retardants to prevent the spread of fire. In this study, decabromodiphenyl ether (BDE-209) and fourteen emerging brominated flame retardants (BFRs) were analyzed in indoor dust, air and on the window surface of newly built low-energy preschools to study their occurrence and distribution. BDE-209 and decabromodiphenyl ethane (DBDPE) were frequently detected in the indoor dust (BDE-209: <4.1-1200 ng/g, DBDPE: <2.2-420 ng/g) and on window surfaces (BDE-209: <1000-20 000 pg/m² , DBDPE: <34-5900 pg/m² ) while the other thirteen BFRs were found in low levels (dust: <0.0020-5.2 ng/g, window surface: 0.0078-35 pg/m² ). In addition, the detection frequencies of BFRs in the indoor air were low in all preschools. Interestingly, the dust levels of BDE-209 and DBDPE were found to be lower in the environmentally certified low-energy preschools, which could be attributed to stricter requirements on the chemical content in building materials and products. However, an increase of some BFR levels in dust was observed which could imply continuous emissions or introduction of new sources.

In 2010, the European Union (EU) introduced the “Energy performance of Buildings” directive, which stipulates that all new buildings must reduce their energy consumption by constructing low-energy buildings. This could be achieved by constructing airtight and energy efficient envelopes with functional building materials such as age-resistant plastic films, insulation and different sealing products. However, functional building materials are known to contain a large amount of man-made chemicals that could be released to the indoor environment and might cause health issues among the occupants. In view of this, the indoor air quality (IAQ) and contamination of selected organic compounds were investigated in newly built low-energy preschools in order to evaluate whether the new building concept, low-energy housing, can have a negative effect to the indoor environment and the occupants. The IAQ was satisfactory in all preschools and the indoor air chemical mixture was heavily influenced by the mechanical heat recovery ventilation system. Furthermore, the levels of formaldehyde, total volatile organic compounds (TVOC), brominated flame retardants (BFRs) and organophosphate flame retardants (OPFRs) were lower in the environmental certified low-energy preschools compared to those preschools without environmental certification. Thus, a conscious choice of building materials, interior decoration and chemical products can reduce the occurrence and levels of hazardous organic compounds. Emission tests showed that collected building materials only contributed to a small fraction of the measured indoor chemical levels. Furthermore, preliminary exposure risk estimation of the indoor chemical mixture showed potential health risk from some individual compounds to the occupants, but further investigations are needed for a more complete risk assessment. In conclusion, the comprehensive and unique study design presented in this thesis will contribute to the ongoing work towards a non-toxic environment, further development of the low-energy building concept and the legislative movement on limit values for chemical emissions from building materials.

The construction of extremely airtight and energy efficient low-energy buildings is achieved by using functional building materials, such as age-resistant plastics, insulation, adhesives, and sealants. Additives such as organophosphate flame retardants (OPFRs) can be added to some of these building materials as flame retardants and plasticizers. Some OPFRs are considered persistent, bioaccumulative and toxic. Therefore, in this pilot study, the occurrence and distribution of nine OPFRs were determined for dust, air, and window wipe samples collected in newly built low-energy preschools with and without environmental certifications. Tris(1,3-dichloroisopropyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP) were detected in all indoor dust samples at concentrations ranging from 0.014 to 10 μg/g and 0.0069 to 79 μg/g, respectively. Only six OPFRs (predominantly chlorinated OPFRs) were detected in the indoor air. All nine OPFRs were found on the window surfaces and the highest concentrations, which occurred in the reference preschool, were measured for 2-ethylhexyl diphenyl phosphate (EHDPP) (maximum concentration: 1500 ng/m²). Interestingly, the OPFR levels in the environmental certified low-energy preschools were lower than those in the reference preschool and the non-certified low-energy preschool, probably attributed to the usage of environmental friendly and low-emitting building materials, interior decorations, and consumer products.