Classroom Dust Research Articles

Assessment of health risk exposure of pupils to classroom dust in some primary schools In Calabar Metropolis, Cross River State, Nigeria

Assessment of health risk exposure of pupils to classroom dust in some primary schools In Calabar Metropolis, Cross River State, Nigeria

Characteristics, sources, and health risks of PAHs and their derivatives in indoor dust in Zhengzhou

The occurrence, source, and health risk of polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs (NPAHs), and oxy-PAHs (OPAHs) in indoor dust collected from three types of microenvironments (offices, classrooms, and dormitories) at a university campus in Zhengzhou were analysed. The results showed that the average concentration of the total PAHs was 2403.21 ± 981.99 ng g−1, with PHE (20.06% of Σ18PAHs) and BkF (15.46%) being the dominant species. The average concentrations of total NPAHs and OPAHs were 11.09 ± 5.12 and 385.80 ± 255.27 ng g−1, with 2+3N-FLT (39.15%) and 9-FLO (39.76%) as the most abundant species of NPAHs and OPAHs, respectively. The average concentrations of total PAHs, NPAHs, and OPAHs in different microenvironments displayed obvious spatial specificity with the highest values in dormitories. The main source of PAHs, as identified by diagnostic ratios, was petroleum combustion, coal/biomass combustion and vehicle exhaust emissions. The average incremental lifetime cancer risk (ILCR) for undergraduates exposed to dust in classrooms and dormitories exceeded 10−6, indicating a potential cancer risk. The most important exposure pathway was dermal contact, while the inhalation route was negligible.

Assessment of the Bacteriological Properties of Indoor Dust in some Classrooms of Delta State University of Science and Technology, Ozoro

The bacteriological properties of indoor dust in some classrooms of the Delta State University of Science, Ozoro was examined with a view to identify any possible source of pollution of classroom indoor air quality; measurement of microbial load of classroom dust sample and to compare findings of selected locations as a means to determine high air polluted areas. This was done by the collection of dust samples from classrooms table and chair surfaces. It was observed that the amount of bacteria available in classrooms differ based on activities in and around the classrooms. Bacteria isolates indicated the presence of pathogen associated with disease such as Bacillus sp; Staphylococcus sp; Micrococcus sp. of indoor air pollution exist and this is identified as open dump practice birthing more microbial cells which are transported through air and poor sanitation practice around and within the classrooms. Contamination of sample was observed for dust at different locations with the bacteria count seen to be higher at sample C (1.8x102cfu/m3) and lower in sample D (0.2x102cfu/m3). Staphylococcus sp dominated all the locations that were analyzed while Micrococcus sp. only occurred in site C. This is because poor environmental sanitation is observed at certain classrooms in addition to shattered classroom windows given an ease of access of dust flow indoor. It can be concluded that only a minimal sources of indoor air pollution exist and hence only a small amount of bacteria is present. In spite of this, prevalence of such practices is likely to promote the growth of more microbial cells.

Seasonal Variation of Indoor Dust Levels of Potential Toxic Heavy Metals in Early Childhood Education Classrooms

The study examines the seasonal variation in potentially toxic heavy metals found in indoor dust in early childhood classrooms, as heavy metal exposure becomes more common in Nigerian childcare settings. Six preschool dust samples from two Nigerian cities were collected during the dry and wet seasons, respectively. After being dried to a consistent weight, the dust samples were ground in a standard pulverizer. The Atomic Absorption Spectroscopy (AAS) method was used to conduct quantitative and qualitative analyses of the samples to determine the heavy metal and elemental composition of the dust in both locations. The dust samples contained seven heavy metals (As, Cd, Co, Cu, Mn, Pb, and Zn), with concentrations varying by season: Co 0.83 µgg-1 to Zn 38.43 µgg-1 during the rainy season, and 1.82 µgg-1 Cu to 80.00 µgg-1 Zn during the dry season. The study concluded that seven elements were present in the sample, and it is recommended that the government of the Federal Republic of Nigeria implement the necessary mechanisms to monitor the impact of dust on preschool children.

Elemental Profiling, Pollution and Health Risks Assessments of Classroom Dust from Selected Nursery and Kindergarten Schools Ogun State, Nigeria

Knowing the concentration of elements in children’s classroom dust and the associated ecological and health risks is essential in preventing and controlling possible elemental poisoning. Dust samples were collected from 37 nursery and kindergarten classrooms across three local government areas in Abeokuta, Nigeria, and assessed for elemental concentrations using X-ray fluorescence (XRF) spectrophotometry. The hazard and the cancer risk indexes were estimated using the geo-accumulation index (Igeo) and health risks posed to children. The highest mean concentrations (mg/kg) of Ca, Fe, K, and Ti ranged between 4034.22–15995.09, 1758.95–2409.62, 5146.66–8996.75, and 730.96–1140.38, respectively. About 33.33% of the monitored metals displayed Igeo values within the moderately polluted and extremely polluted categories in Abeokuta South and North. All the monitored locations were strongly polluted with Ca, Fe, K and Ti, including arsenic at Abeokuta South. Metals with high pollution (Cf > 6) were Ca, Fe, Co, As, K, Ti and Ge in Abeokuta South. Ca, Fe, Co, As, K, Sc, Ti and Ge in Abeokuta North; and Ca, Fe, As, K, Sc, Ti and Ge at Odeda. Arsenic levels were 128.42 (considerable), 2934.27 (very high) and 179.33 (high) for the ecological risk factors. Dust samples for Abeokuta South and North posed the least and greatest ecological risks, respectively, and the risk potentials of arsenic across all the locations were in the ecologically risky ranges. However, hazard indexes < 1 were recorded across the monitored sites, indicating no immediate non-carcinogenic health risks, while cancer risks for Co, Ni, As, and Cr were < 1.0E−04, respectively, depicting no significant carcinogenic risk. This study concluded that the levels of elements monitored do not pose any health risk to the children but are of concern to the ecosystem. Therefore, policies on locating schools in areas with minimum anthropogenic pollution should be formulated and continuous cleaning of classroom surfaces should be encouraged.

Source apportionment of children daily exposure to particulate matter

The present study aims to investigate the sources of particulate pollution in indoor and outdoor environments, with focus on determining their contribution to the exposure of children to airborne particulate matter (PM). To this end, parallel indoor and outdoor measurements were carried out for a selection of 40 homes and 5 schools between September 2017 and October 2018. PM2.5 and PM2.5–10 samples were collected during five days in each microenvironment (ME) and analysed by X-Ray Fluorescence (XRF), for the determination of elements, and by a thermal-optical technique, for the measurement of organic and elemental carbon. The source apportionment analysis of the PM composition data, by means of the receptor model SoFi (Source Finder) 8 Pro, resulted in the identification of nine sources: exhaust and non-exhaust emissions from traffic, secondary particles, heavy oil combustion, industry, sea salt, soil, city dust, and an indoor source characterized by high levels of organic carbon. Integrated daily exposure to PM2.5 was on average 21 μg/m3. The organic matter, resulting from cleaning, cooking, smoking and biological material, was the major source contributing by 31% to the PM2.5 exposure. The source city dust, which was highly influenced by the resuspension of dust in classrooms, was the second main source (26%), followed by traffic (24%). The major sources affecting the integrated exposure to PM10, which was on average 33 μg/m3, were the city dust (39%), indoor organics (24%) and traffic (16%). This study provides important information for the design of measures to reduce the exposure of children to PM.

Microplastics in the school classrooms of Shiraz, Iran

Microplastics (MPs) are a pervasive and ubiquitous environmental contaminant. However, very little information exists on the quantities or characteristics of MPs in the indoor setting. In the present study, MPs have been isolated from settled classroom dust samples collected from 50 schools in the city of Shiraz, Iran. Concentrations of MPs on a number basis ranged from about 80 to over 56,000 MP per g of dry dust and there was an increase in concentration towards the centre and southeast of the city. The geographical distribution is attributed to a larger population and student density, higher traffic loading and greater industrialization in the centre and southeast and a prevailing wind from the northwest. MPs were dominated by fibres of >250 μm in length, and Raman spectrometry and SEM-EDX analysis of selected samples revealed that MPs were mainly constructed of polyethylene terephthalate or polypropylene but were contaminated by various metals (e.g. lead, titanium, antimony) used as additives or acquired from the environment. Calculations using data for elementary schools indicate that children in the age range 6–14 years may be exposed to between about 5 and 440 MP day−1 through inadvertent ingestion. The health impacts of MPs on children are unknown but the results of the present study indicate a requirement for research in this area.

The Toxicity of Wiped Dust and Airborne Microbes in Individual Classrooms Increase the Risk of Teachers' Work-Related Symptoms: A Cross-Sectional Study.

Background: The causes and pathophysiological mechanisms of building-related symptoms (BRS) remain open. Objective: We aimed to investigate the association between teachers’ individual work-related symptoms and intrinsic in vitro toxicity in classrooms. This is a further analysis of a previously published dataset. Methods: Teachers from 15 Finnish schools in Helsinki responded to the symptom survey. The boar sperm motility inhibition assay, a sensitive indicator of mitochondrial dysfunction, was used to measure the toxicity of wiped dust and cultured microbial fallout samples collected from the teachers’ classrooms. Results: 231 teachers whose classroom toxicity data had been collected responded to the questionnaire. Logistic regression analysis adjusted for age, gender, smoking, and atopy showed that classroom dust intrinsic toxicity was statistically significantly associated with the following 12 symptoms reported by teachers (adjusted ORs in parentheses): nose stuffiness (4.1), runny nose (6.9), hoarseness (6.4), globus sensation (9.0), throat mucus (7.6), throat itching (4.4), shortness of breath (12.2), dry cough (4.7), wet eyes (12.7), hypersensitivity to sound (7.9), difficulty falling asleep (7.6), and increased need for sleep (7.7). Toxicity of cultured microbes was found to be associated with nine symptoms (adjusted ORs in parentheses): headache (2.3), nose stuffiness (2.2), nose dryness (2.2), mouth dryness (2.8), hoarseness (2.2), sore throat (2.8), throat mucus (2.3), eye discharge (10.2), and increased need for sleep (3.5). Conclusions: The toxicity of classroom dust and airborne microbes in boar sperm motility inhibition assay significantly increased teachers’ risk of work-related respiratory and ocular symptoms. Potential pathophysiological mechanisms of BRS are discussed.

Indoor bacterial, fungal and viral species and functional genes in urban and rural schools in Shanxi Province, China\u2013association with asthma, rhinitis and rhinoconjunctivitis in high school students

BackgroundStudies in developed countries have reported that the prevalence of asthma and rhinitis is higher in urban areas than in rural areas, and this phenomenon is associated with urbanization and changing indoor microbiome exposure. Developing countries such as China have experienced rapid urbanization in past years, but no study has investigated microbiome exposure and urban-rural health effects in these countries.MethodsNine high schools from urban and rural areas were randomly selected in Shanxi Province, China, and classroom vacuum dust was collected for shotgun metagenomic sequencing. A self-administered questionnaire was collected from 1332 students for personal information and health data. Three-level logistic regression was performed between microbial richness/abundance/functional pathways and the occurrence of asthma and rhinitis symptoms.ResultsConsistent with developed countries, the prevalence of wheeze and rhinitis was higher in urban areas than in rural areas (p < 0.05). Metagenomic profiling revealed 8302 bacterial, 395 archaeal, 744 fungal, 524 protist and 1103 viral species in classroom dust. Actinobacteria (mean relative abundance 49.7%), Gammaproteobacteria (18.4%) and Alphaproteobacteria (10.0%) were the most abundant bacterial classes. The overall microbiome composition was significantly different between urban and rural schools (p = 0.001, Adonis). Species from Betaproteobactera, Gammaproteobacteria and Bacilli were enriched in urban schools, and species from Actinobacteria and Cyanobacteria were enriched in rural schools. Potential pathogens were present in higher abundance in urban schools than in rural schools (p < 0.05). Pseudoalteromonas, Neospora caninum and Microbacterium foliorum were positively associated with the occurrence of wheeze, rhinitis and rhinoconjunctivitis, and Brachybacterium was protectively (negatively) associated with rhinitis (p < 0.01). The abundance of human endocrine and metabolic disease pathways was positively associated with rhinitis (p = 0.008), and butyrate and propionate metabolic genes and pathways were significantly enriched in rural schools (p < 0.005), in line with previous findings that these short-chain fatty acids protect against inflammatory diseases in the human gut.ConclusionsWe conducted the first indoor microbiome survey in urban/rural environments with shotgun metagenomics, and the results revealed high-resolution microbial taxonomic and functional profiling and potential health effects.2wRPURVCNzispD2jVrrnAmVideo abstract

ATR-FTIR and LC-Q-ToF-MS analysis of indoor dust from different micro-environments located in a tropical metropolitan area

Indoor dust is an important matrix that exposes humans to a broad spectrum of chemicals. The information on the occurrence of contaminants of emerging concern (CECs), their metabolites, and re-emerging contaminants in indoor dust is rather limited. As the indoor environment is exposed to various chemicals from personal care products, furniture, building materials, machineries and cooking/cleaning products, there is a high chance of the presence of hazardous contaminants in indoor dust. In the present study, dust samples were collected from four different micro indoor environments (photocopying centres, residential houses, classrooms, and ATM cabins) located in an urban environment located in India's southwestern part. The collected samples were subjected to ATR – FTIR and LC-Q-ToF-MS analyses. The ATR – FTIR analysis indicated the presence of aldehydes, anhydrides, carboxylic acids, esters, sulphonic acids, and asbestos – a re-emerging contaminant. A total of 19 compounds were identified from the LC-Q-ToF-MS analysis. These compounds belonged to various classes such as plasticisers, plasticiser metabolites, photoinitiators, personal care products, pharmaceutical intermediates, surfactants, and pesticides. To the best of our knowledge, this is the first report regarding the presence of CECs in indoor environments in Kerala and also the suspected occurrence of pesticides (metaldehyde and ethofumesate) in classroom dust in India. Another important highlight of this work is the demonstration of ATR-FTIR as a complementary technique for LC-Q-ToF-MS in the analysis of indoor pollution while dealing with totally unknown pollutants. These results further highlight the occurrence of probable chemically modified metabolites in the tropical climatic conditions in a microenvironment.

Characterization and source identification of fine dust in Seoul elementary school classrooms

To evaluate the level of fine particulate matters in elementary schools located in a high traffic area of Seoul and verify the emission source, a field study on the classrooms was conducted under the uncontrolled condition. The indoor PM2.5 was lower than that of the outdoors as indicated by an I/O ratio of 0.52–0.92 based on mass concentration, and it was maintained below the National Guideline. Heavy metals such as Cr, Mn, Ni, Cu, Zn, As, Sn and Pb were lower in indoor PM2.5 than outdoors. On the contrary, carbons including OC and EC were higher in indoor PM2.5. As a result of source apportionment analysis, an outdoor emission source was responsible for 58.5% of the classroom PM2.5. This study can contribute to urban planning and school design to keep children safe from harmful environments.

The Safety of Schools Based on Heavy Metal Concentrations in Classrooms' Dust: A Systematic Review and Meta-Analysis.

Background:Classroom is where children spend much of their time in; this study aimed to identify the concentration of heavy metals in the classroom dust based on the results of various studies in the world using the published data up to years 2018.Methods:Fifteen studies were selected for the study according to the inclusion and exclusion criteria. The mean concentration of 11 heavy metals including arsenic, barium, cadmium, cobalt, chromium, copper, iron, lead, manganese, nickel, and zinc was extracted.Results:The highest mean concentration of heavy metal (mg/kg) in classroom dust was related to iron (3904.7, 95%CI: 3657.1–8154.3), zinc (429.9, 95%CI: 182.8–677.1) and barium (419.2, 95%CI: 274.7–253.7), respectively. Subgroup analysis showed the maximum concentration (mg/kg) of iron in Iran (16945.5), zinc in Hong Kong (2293.5), barium in China (979.8), manganese in Iran (288.9), lead in Iran (258.8), chromium in Ghana (381.3), copper in Hong Kong (274.4), nickel in Iran (50.1), cobalt in China(43.4), arsenic in China(13.7) and cadmium in Hong Kong(8.7).Conclusion:Even safe and healthy classrooms can threaten children’s health by heavy metals. These metals are important since they are naturally found throughout the earth’s crust, accumulate in the food chain and contaminate drinking water as well as alloys in school equipment.

Heavy metal concentration in classroom dust samples and its relationship with childhood asthma: a study from Islamic Republic of Iran.

Classrooms are an important environment for young children as this is where they spend a large part of their time. This study was designed to quantify the levels of heavy metals in classroom dusts in Shiraz, a city southwestern Iran. The potential association between heavy metal levels and childhood asthma was also investigated. We selected 32 schools for collecting classroom dust samples during September-November 2016. The concentration of 10 heavy metals was measured in these dust samples by optical emission spectrometry. The diagnosis of childhood asthma was made using both the medical chart of each student and examination by an allergist. The data were analysed using SPSS, version 21.0. The concentration of heavy metals in classroom dust samples ranged from 7559 to 53 723.0 mg/kg (mean: 16 945.5 mg/kg) for Fe, 169.0 to 952.0 mg/kg (mean 288.9 mg/kg) for Mn, and 9.0 to 971.0 mg/kg (mean 258.8 mg/kg) for Pb. We found no correlation between heavy metals in classroom dust and childhood asthma. In comparison with studies reported elsewhere, the maximum levels of lead in our study were greater. A potential explanation for the lack of correlation with childhood asthma is the large mass of the particles, preventing them from reaching the lower airways. Nevertheless, special attention should be paid to reducing high levels of heavy metals in classroom dust in this area.

Classroom Dust-Bound Polycyclic Aromatic Hydrocarbons in Jeddah Primary Schools, Saudi Arabia: Level, Characteristics and Health Risk Assessment.

Data concerning polycyclic aromatic hydrocarbons (PAHs) in Jeddah’s schools, Saudi Arabia, and their implications for health risks to children, is scarce. Classroom air conditioner filter dusts were collected from primary schools in urban, suburban and residential areas of Jeddah. This study aimed to assess the characteristics of classroom-dust-bound PAHs and the health risks to children of PAH exposure. Average PAH concentrations were higher in urban schools than suburban and residential schools. Benzo (b)fluoranthene (BbF), benzo(ghi)perylene (BGP), chrysene (CRY) and Dibenz[a,h]anthracene (DBA) at urban and suburban schools and BbF, BGP, fluoranthene (FLT) and indeno (1, 2, 3, −cd)pyrene (IND) at residential schools were the dominant compounds in classroom dust. PAHs with five aromatic rings were the most abundant at all schools. The relative contribution of the individual PAH compounds to total PAH concentrations in the classroom dusts of schools indicate that the study areas do share a common source, vehicle emissions. Based on diagnostic ratios of PAHs, they are emitted from local pyrogenic sources, and traffic is the significant PAH source, with more significant contributions from gasoline-fueled than from diesel cars. Based on benzo[a]pyrene equivalent (BaPequi) calculations, total carcinogenic activity (TCA) for total PAHs represent 21.59% (urban schools), 20.99% (suburban schools), and 18.88% (residential schools) of total PAH concentrations. DBA and BaP were the most dominant compounds contributing to the TCA, suggesting the importance of BaP and DBA as surrogate compounds for PAHs in this schools. Based on incremental lifetime cancer risk (ILCingestion, ILCRinhalation, ILCRdermal) and total lifetime cancer risk (TLCR)) calculations, the order of cancer risk was: urban schools > suburban schools > residential schools. Both ingestion and dermal contact are major contributors to cancer risk. Among PAHs, DBA, BaP, BbF, benzo(a)anthracene (BaA), benzo(k)fluoranthene (BkF), and IND have the highest ILCR values at all schools. LCR and TLCR values at all schools were lower than 10−6, indicating virtual safety. DBA, BaP and BbF were the predominant contributors to cancer effects in all schools.

Malaysia: country report on children's environmental health.

Children's environmental health (CEH) has become a main agenda in the National Environmental Health Action Plan (NEHAP) 2019 in Malaysia. Children are affected by exposure to many environmental hazards because they are uniquely vulnerable due to their immature immune systems and organs. This country report aims to review the environmental threats to CEH in Malaysia. There are a few key issues that have been identified, including air pollution, pesticides in food and water pollution. However, air pollution has been recognized as one of the major concerns in CEH, coming from both localized and transboundary sources. The localized sources include traffic-related air pollutants, industrial waste incinerators, land clearing and open burning. In addition, due to the tropical climate, children are exposed to fungal toxins, mycotoxins, endotoxins and allergens from classroom dust. Transboundary pollutants from neighboring countries result in recurring haze episodes in Malaysia, causing a negative impact on public health, especially in children. All in all, improving CEH in Malaysia requires all stakeholders and related agencies to recognize the issue as a problem, to develop a harmonized action plan and to work together to promote the protection of human health, specifically of children.

The level of allergens in dust samples collected from selected schools in Shiraz, Iran and its asthma-risk implications

BackgroundBoth home and school are important places where children are exposed to various indoor allergens. This study aimed to identify the profile of indoor allergens in schools and its impact on asthma development. MethodsA total of 104 classrooms from 52 schools were selected for dust collection during the fall of 2017. The levels of indoor allergens including dust mite (Der f1, Der p1), cat (Fel d1), cockroach (Bla g1) and mouse (Mus m1) were measured by enzyme linked immunosorbent assay (ELISA). The diagnosis of asthma was made in all students of the selected classes by the allergist. The collected data were analyzed using SPSS version 21.0. ResultsOut of 2816 students in the selected classes, 180 students were involved with asthma. Students were mostly exposed to Bla g1 (83.1%), followed by Der f1 (51.5%), Mus m 1 (45.5%), Der p1 (8.9%) and Fel d1 (7.9%) in the dust collected from 101 classrooms. Although levels of all studied allergens in the settled dust of the classrooms were low, there was a relationship between Fel d1 in the classroom dust and development of asthma. ConclusionThis study showed considerable levels of cockroach allergens in schools. Exposure to cat allergen in our schools played an important role in asthma development; further school-based investigations require evaluating the role of classroom allergen on asthma development.

The exposure of children to PM2.5 and dust in indoor and outdoor school classrooms in Kuala Lumpur City Centre

It is important to assess indoor air quality in school classrooms where the air quality may significantly influence school children's health and performance. This study aims to determine the concentrations of PM2.5 and dust chemical compositions in indoor and outdoor school classroom located in Kuala Lumpur City Centre. The PM2.5 concentration was measured from 19th September 2017–16th February 2018 using an optical PM2.5 sensor. Indoor and outdoor dust was also collected from the school classrooms and ion and trace metal concentrations were analysed using ion chromatography (IC) and inductively couple plasma-mass spectrometry (ICP-MS) respectively. This study showed that the average indoor and outdoor 24 h PM2.5 was 11.2 ± 0.45 µg m−3 and 11.4 ± 0.44 µg m−3 respectively. The 8 h PM2.5 concentration ranged between 3.2 and 28 µg m−3 for indoor and 3.2 and 19 µg m−3 for outdoor classrooms. The highest ion concentration in indoor dust was Ca2+ with an average concentration of 38.5 ± 35.0 µg g−1 while for outdoor dust SO42- recorded the highest ion concentration with an average concentration of 30.6 ± 9.37 µg g−1. Dominant trace metals in both indoor and outdoor dust were Al, Fe and Zn. Principle component analysis-multiple linear regression (PCA-MLR) demonstrated that the major source of indoor dust was road dust (69%), while soil dominated the outdoor dust (74%). Health risk assessment showed that the hazard quotient (HQ) value for non-carcinogenic trace metals was < 1 while the total cancer risk (CR) value for carcinogenic elements was below the acceptable limit for both indoor and outdoor dust through dermal and inhalation pathways, but not the ingestion pathway. This study suggests indoor contributions of PM2.5 concentrations are due to the activities of the school children while the compositions of indoor and outdoor dust are greatly influenced by the soil/earth source plus industrial and traffic contribution.

Heavy metal quantification of classroom dust in school environment and its impacts on children health from Rawang (Malaysia).

This study aimed to determine bioavailable heavy metal concentrations (As, Cd, Co, Cu, Cr, Ni, Pb, Zn) and their potential sources in classroom dust collected from children's hand palms in Rawang (Malaysia). This study also aimed to determine the association between bioavailable heavy metal concentration in classroom dust and children's respiratory symptoms. Health risk assessment (HRA) was applied to evaluate health risks (non-carcinogenic and carcinogenic) due to heavy metals in classroom dust. The mean of bioavailable heavy metal concentrations in classroom dust found on children's hand palms was shown in the following order: Zn (1.25E + 01μg/g) > Cu (9.59E-01μg/g) > Ni (5.34E-01μg/g) > Cr (4.72E-02μg/g) > Co (2.34E-02μg/g) > As (1.77E-02μg/g) > Cd (9.60E-03μg/g) > Pb (5.00E-03μg/g). Hierarchical cluster analysis has clustered 17 sampling locations into three clusters, whereby cluster 1 (S3, S4, S6, S15) located in residential areas and near to roads exposed to vehicle emissions, cluster 2 (S10, S12, S9, S7) located near Rawang town and cluster 3 (S13, S16, S1, S2, S8, S14, S11, S17, S5) located near industrial, residential and plantation areas. Emissions from vehicles, plantations and industrial activities were found as the main sources of heavy metals in classroom dust in Rawang. There is no association found between bioavailable heavy metal concentrations and respiratory symptoms, except for Cu (OR = 0.03). Health risks (non-carcinogenic and carcinogenic risks) indicated that there are no potential non-carcinogenic and carcinogenic risks of heavy metals in classroom dust toward children health.

Levels of heavy metals in deposited dust and soil from selected primary schools in Dar es Salaam

The objective of this study was to examine the levels of heavy metals, lead, manganese, nickel, copper, chromium and cadmium in standard one and kindergarten classroom dusts and playing ground soils from selected primary schools along Morogoro road highway (Kimara, Mbezi, Kibamba and Kiluvya primary schools) and away from Morogoro road highway (Makabe, Msumi and Mbopo primary schools) as well as in the Dar es Salaam city center (Uhuru, Mzimuni, Dr. Omari Ali Juma, Manzese and Ubungo National House primary schools), Tanzania. The samples were acid digested and the supernatant analyzed using inductively coupled plasma optical emission spectrometer (ICP-OES). The mean concentrations (mg/kg) range of heavy metals in kindergarten and standard one classroom dust samples were bdl – 3.2 ± 0.2 (Cd), 14.7 ± 0.5 – 30.1 ± 2.2 (Cr), 6701 ± 1201 – 277775 ± 32632 (Mn), 5.18 ± 0.59 – 122 ± 145 (Cu), 6.95 ± 1.57 – 30.3 ± 31.1 (Ni) and 17.67 ± 3.56 – 104.9 ± 94.7 (Pb). Similarly, t he mean concentrations (mg/kg) range of heavy metals in kindergarten and standard one playing ground soil samples were bdl – 1.86 ± 0.06 (Cd), 5.8 ± 0.8 – 105 ± 124 (Cr), 7176 ± 226 – 191779 ± 82776 (Mn), 1.64 ± 0.01 – 11.51 ± 6.5 (Cu), 1.11 ± 0.2 – 37.5 ± 45.9 (Ni) and 8.9 ± 2.4 – 34.04 ± 1.9 (Pb). The present results, which indicate significantly high levels of heavy metals in school classroom dusts and playing ground soils, signify an important advancement towards shedding light on the alarming threat to school children’s health since classrooms and playing grounds are their immediate environments where they spend significant amount of their early life time. Keywords : Heavy metals, lead, manganese, nickel, copper, chromium, cadmium, classrooms dusts, Tanzania

Levels, occurrence and human exposure to novel brominated flame retardants (NBFRs) and Dechlorane Plus (DP) in dust from different indoor environments in Hangzhou, China

In this work, sixteen novel brominated flame retardants (NBFRs) and Dechlorane Plus (DP) were investigated in dust samples collected from different indoor environments (home, office, laboratory, classroom and dormitory) in Hangzhou, China. High detection frequencies for most of the congeners were observed, suggesting the widespread use of NBFRs and DP. The mean concentrations of ∑16NBFRs were 389ngg−1 in the home dust, 1125ngg−1 in the office dust, 204ngg−1 in the laboratory dust, 259ngg−1 in the classroom dust, and 825ngg−1 in the dormitory dust. Regarding DP, the mean concentrations of DP were 106ngg−1 in the office dust, 59ngg−1 in the dormitory dust, 56ngg−1 in the classroom dust, 52ngg−1 in the home dust, and 40ngg−1 in the laboratory dust. The concentrations of NBFRs and DP in the indoor dust were positively related to the number of indoor electric appliances and negatively related to the air ventilation rate. The age of the interior decoration has a profound effect on the concentration of NBFRs in indoor dust. The daily exposure doses (DED) of NBFRs and DP were estimated to be 4595pg (kgbw)−1d−1 for toddlers and 1099pg (kgbw)−1d−1 for adults. Thus, toddlers have a higher risk for NBFRs exposure than adults. The DED of young adults in college in different indoor microenvironments decreased in the following order: dormitory (657pg (kg bw)−1d−1)>laboratory (145pg (kgbw)−1d−1)>classroom (140pg (kgbw)−1d−1). More attention should be paid to the exposure of young adults to indoor pollutants, which has not previously been the subject of great concern.