Drinking water quality status in Malaysia: a scoping review of occurrence, human health exposure, and potential needs.

BACKGROUND: Like other countries, surface water degradation in Malaysia is linked with common global issues. Although different aspects of drinking water suitability have been examined, the overall understanding of drinking water quality in Malaysia is poor. OBJECTIVE: Hence, the present review aims to provide an understanding of drinking water (tap water, groundwater, gravity feed system) quality and its potential implications on policy, human health, and drinking water management law and identification of potential direction of future drinking water research and management needs in Malaysia. METHODS: This study utilized a scoping review method. PRISMA Extension for Scoping Reviews was used for search strategy. Relevant studies were screened using the selected keywords and databases. RESULTS: A total of 26 drinking water quality studies involving tap water, groundwater, and gravity feed systems have been selected for review. These studies found that the majority of Malaysian Drinking Water and WHO Drinking Water standards have been met. High levels of Cu, Cd, Fe and Pb were attributable to galvanized plumbing and pipe material corrosion. Variation of fluoride in tap water depends on dosage planning and operational processes of the public water supply. Pollutants (nitrate and ammonia) in groundwater and gravity feed system water have been linked to agricultural practices in rural areas. Microbiological quality in tap water is associated with growing biofilms inside the pipelines while in groundwater is caused by shallow surface events. However, only eight studies have reported about the human risks of chemical pollutants in tap water. IMPACT STATEMENT: The review discusses the state of drinking water quality in Malaysia and its impact on public health. It suggests that policymakers can use this information to improve the quality of drinking water and enforce restrictions, while also raising public awareness about the importance of safe drinking water. The study can guide future research and initiatives in Malaysia, ultimately contributing to efforts to ensure access to clean and dependable drinking water.

Investigation of the impacts of climate change and rising temperature on food poisoning cases in Malaysia.

This study is an attempt to investigate climate-induced increases in morbidity rates of food poisoning cases. Monthly food poisoning cases, average monthly meteorological data, and population data from 2004 to 2014 were obtained from the Malaysian Ministry of Health, Malaysian Meteorological Department, and Department of Statistics Malaysia, respectively. Poisson generalised linear models were developed to assess the association between climatic parameters and the number of reported food poisoning cases. The findings revealed that the food poisoning incidence in Malaysia during the 11 years study period was 561 cases per 100 000 population for the whole country. Among the cases, females and the ethnic Malays most frequently experienced food poisoning with incidence rates of 313 cases per 100,000 and 438 cases per 100,000 population over the period of 11 years, respectively. Most of the cases occurred within the active age of 13 to 35 years old. Temperature gave a significant impact on the incidence of food poisoning cases in Selangor (95% CI: 1.033-1.479; p = 0.020), Melaka (95% CI: 1.046-2.080; p = 0.027), Kelantan (95% CI: 1.129-1.958; p = 0.005), and Sabah (95% CI: 1.127-2.690; p = 0.012) while rainfall was a protective factor in Terengganu (95% CI: 0.996-0.999; p = 0.034) at lag 0 month. For a 1.0°C increase in temperature, the excess risk of food poisoning in each state can increase up to 74.1%, whereas for every 50 mm increase in rainfall, the risk of getting food poisoning decreased by almost 10%. The study concludes that climate does affect the distribution of food poisoning cases in Selangor, Melaka, Kelantan, Sabah, and Terengganu. Food poisoning cases in other states are not directly associated with temperature but related to monthly trends and seasonality.

Associations between environmental characteristics, high-resolution indoor microbiome, metabolome and allergic and non-allergic rhinitis symptoms for junior high school students.

Rhinitis is one of the most prevalent chronic diseases globally. Microbiome exposure affects the occurrence of rhinitis. However, previous studies did not differentiate allergic rhinitis (AR) and non-allergic rhinitis (NAR) in the microbial association analysis. In this study, we investigate 347 students in 8 junior high schools, Terengganu, Malaysia, who were categorized as healthy (70.9%), AR (13.8%) and NAR (15.3%) based on a self-administered questionnaire and skin prick tests of pollen, pet, mould and house dust mite allergens. Classroom microbial and metabolite exposure in vacuumed dust was characterized by PacBio long-read amplicon sequencing, quantitative PCR and LC-MS-based untargeted metabolomics. Our findings indicate a similar microbial association pattern between AR and NAR. The richness in Gammaproteobacteria was negatively associated with AR and NAR symptoms, whereas total fungal richness was positively associated with AR and NAR symptoms (p < 0.05). Brasilonema bromeliae and Aeromonas enteropelogenes were negatively associated with AR and NAR, and Deinococcus was positively associated with AR and NAR (p < 0.01). Pipecolic acid was protectively associated with AR and NAR symptoms (OR = 0.06 and 0.13, p = 0.009 and 0.045). A neural network analysis showed that B. bromeliae was co-occurring with pipecolic acid, suggesting that the protective role of this species may be mediated by releasing pipecolic acid. Indoor relative humidity and the weight of vacuum dust were associated with AR and NAR, respectively (p < 0.05), but the health effects were mediated by two protective bacterial species, Aliinostoc morphoplasticum and Ilumatobacter fluminis. Overall, our study reported a similar microbial association pattern between AR and NAR and also revealed the complex interactions between microbial species, environmental characteristics, and rhinitis symptoms.

Microbial Virulence Factors, Antimicrobial Resistance Genes, Metabolites, and Synthetic Chemicals in Cabins of Commercial Aircraft.

Passengers are at a higher risk of respiratory infections and chronic diseases due to microbial exposure in airline cabins. However, the presence of virulence factors (VFs), antimicrobial resistance genes (ARGs), metabolites, and chemicals are yet to be studied. To address this gap, we collected dust samples from the cabins of two airlines, one with textile seats (TSC) and one with leather seats (LSC), and analyzed the exposure using shotgun metagenomics and LC/MS. Results showed that the abundances of 17 VFs and 11 risk chemicals were significantly higher in TSC than LSC (p < 0.01). The predominant VFs in TSC were related to adherence, biofilm formation, and immune modulation, mainly derived from facultative pathogens such as Haemophilus parainfluenzae and Streptococcus pneumoniae. The predominant risk chemicals in TSC included pesticides/herbicides (carbofuran, bromacil, and propazine) and detergents (triethanolamine, diethanolamine, and diethyl phthalate). The abundances of these VFs and detergents followed the trend of TSC > LSC > school classrooms (p < 0.01), potentially explaining the higher incidence of infectious and chronic inflammatory diseases in aircraft. The level of ARGs in aircraft was similar to that in school environments. This is the first multi-omic survey in commercial aircraft, highlighting that surface material choice is a potential intervention strategy for improving passenger health.

Arsenic in drinking water, hair, and prevalence of arsenicosis in Perak, Malaysia.

Arsenic is a carcinogen element that occurs naturally in our environment. Humans can be exposed to arsenic through ingestion, inhalation, and dermal absorption. However, the most significant exposure pathway is via oral ingestion. Therefore, a comparative cross-sectional study was conducted to determine the local arsenic concentration in drinking water and hair. Then, the prevalence of arsenicosis was evaluated to assess the presence of the disease in the community. The study was conducted in two villages, namely Village AG and Village P, in Perak, Malaysia. Socio-demographic data, water consumption patterns, medical history, and signs and symptoms of arsenic poisoning were obtained using questionnaires. In addition, physical examinations by medical doctors were performed to confirm the signs reported by the respondents. A total of 395 drinking water samples and 639 hair samples were collected from both villages. The samples were analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) to determine arsenic concentration. The results showed that 41% of water samples from Village AG contained arsenic concentrations of more than 0.01 mg/L. In contrast, none of the water samples from Village P exceeded this level. Whilst, for hair samples, 85 (13.5%) of total respondents had arsenic levels above 1 µg/g. A total of 18 respondents in Village AG had at least one sign of arsenicosis and hair arsenic levels of more than 1 µg/g. Factors significantly associated with increased arsenic levels in hair were female, increasing age, living in Village AG and smoking. The prevalence of arsenicosis in the exposed village indicates chronic arsenic exposure, and immediate mitigation action needs to be taken to ensure the wellbeing of the residents in the exposed village.

A priority list of environmental health issues for Malaysia.

OBJECTIVES: Environmental risk factors contribute to 24% of the global burden of disease from all causes in disability-adjusted life years (DALYs), and to 23% of all global deaths. Malaysia being an advanced developing country, there is a need to prioritise environmental health issues to enable environmental health practitioners to focus on the most significant and urgent environmental health concerns. CONTENT: This project was undertaken by a Thematic Working Group on Environmental Health Experts (TWG 10) under the Malaysian National Environmental Health Action Plan. Sixteen pre-selected environmental health issues were presented to a two focus group discussions among 20 environmental health and related professionals who then scored each issue on its magnitude and severity scale. SUMMARY: The total of these scores generated a list of priority environmental health issues for Malaysia. Children environmental health came out as the environmental health issue of the highest priority. OUTLOOK: We hope that this list of priority environmental health issues will be used for prioritising academic and professional manpower training, research funding allocation and planning for intervention programmes by various stakeholders.

Indoor metabolites and chemicals outperform microbiome in classifying childhood asthma and allergic rhinitis.

Indoor microorganisms impact asthma and allergic rhinitis (AR), but the associated microbial taxa often vary extensively due to climate and geographical variations. To provide more consistent environmental assessments, new perspectives on microbial exposure for asthma and AR are needed. Home dust from 97 cases (32 asthma alone, 37 AR alone, 28 comorbidity) and 52 age- and gender-matched controls in Shanghai, China, were analyzed using high-throughput shotgun metagenomic sequencing and liquid chromatography-mass spectrometry. Homes of healthy children were enriched with environmental microbes, including Paracoccus, Pseudomonas, and Psychrobacter, and metabolites like keto acids, indoles, pyridines, and flavonoids (astragalin, hesperidin) (False Discovery Rate < 0.05). A neural network co-occurrence probability analysis revealed that environmental microorganisms were involved in producing these keto acids, indoles, and pyridines. Conversely, homes of diseased children were enriched with mycotoxins and synthetic chemicals, including herbicides, insecticides, and food/cosmetic additives. Using a random forest model, characteristic metabolites and microorganisms in Shanghai homes were used to classify high and low prevalence of asthma/AR in an independent dataset in Malaysian schools (N = 1290). Indoor metabolites achieved an average accuracy of 74.9% and 77.1% in differentiating schools with high and low prevalence of asthma and AR, respectively, whereas indoor microorganisms only achieved 51.0% and 59.5%, respectively. These results suggest that indoor metabolites and chemicals rather than indoor microbiome are potentially superior environmental indicators for childhood asthma and AR. This study extends the traditional risk assessment focusing on allergens or air pollutants in childhood asthma and AR, thereby revealing potential novel intervention strategies for these diseases.

Fractional exhaled nitric oxide (FeNO) and respiratory symptoms in junior high school students in Penang, Malaysia: the role of household exposure.

We studied associations between fractional exhaled nitric oxide (FeNO), health and household exposure among school children (N = 348) in Penang, Malaysia. Multiple logistic regression and linear mixed models were applied. Overall, 46.0% had elevated FeNO (>20 ppb) and 10.6% diagnosed asthma. Male gender (p = 0.002), parental asthma or allergy (p = 0.047), cat allergy (p = 0.009) and seafood allergy (p < 0.001), diagnosed asthma (p = 0.001), wheeze (p = 0.001), ocular symptoms (p = 0.001), rhinitis (p = 0.002) and respiratory infections (p = 0.004) were all associated with FeNO. Students exposed to ETS had lower FeNO (p = 0.05). Dampness and mould was associated with wheeze (p = 0.038), especially in wooden homes (interaction p = 0.042) and among students with elevated FeNO (interaction p = 0.024). Cat keeping increased rhinitis (p = 0.041) and respiratory infections (p = 0.008) and modified the dampness associations. In conclusion, FeNO can be associated with ocular and respiratory symptoms. Elevated FeNO, cat keeping and a wooden house can enhance the risk of wheeze when exposed to dampness and mould.

Fungi composition in settled dust associated with fractional exhaled nitric oxide in school children with asthma.

Fungi exposure has been significantly linked to respiratory illness. However, numerous fungi taxa that are potentially allergenic still undocumented and leave a barrier to establishing a clear connection between exposure and health risks. This study aimed to evaluate the association of fungi composition in settled dust with fractional exhaled nitric oxide (FeNO) levels among school children with doctor-diagnosed asthma. A cross-sectional study was undertaken among secondary school students in eight schools in the urban area of Hulu Langat, Selangor, Malaysia. A total of 470 school children (aged 14 years old) were randomly selected and their FeNO levels were measured and allergic skin prick tests were conducted. The settled dust samples were collected and analysed by using metagenomic technique to determine the fungi composition. The general linear regression with complex sampling was employed to determine the interrelationship. In total, 2645 fungal operational taxonomic units (OTUs) were characterised from the sequencing process which belongs to Ascomycota (60.7 %), Basidiomycota (36.4 %), Glomeromycota (2.9 %) and Chytridiomycota (0.04 %). The top five mostly abundance in all dust samples were Aspergillus clavatus (27.2 %), followed by Hyphoderma multicystidium (12.2 %), Verrucoconiothyrium prosopidis (9.4 %), Ganoderma tuberculosum (9.2 %), and Heterochaete shearii (7.2 %). The regression results indicated that A. clavatus, Brycekendrickomyces acaciae, Candida parapsilosis, Hazslinszkyomyces aloes, H. multicystidium, H. shearii, Starmerella meliponinorum, V. prosopidis were associated in increased of FeNO levels among the asthmatic group at 0.992 ppb (95 % CI = 0.34-1.68), 2.887 ppb (95 % CI = 2.09-3.76), 0.809 ppb (95 % CI = 0.14-1.49), 0.647 ppb (95 % CI = 0.36-0.94), 1.442 ppb (95 % CI = 0.29-2.61), 1.757 ppb (95 % CI = 0.59-2.87), 1.092 ppb (95 % CI = 0.43-1.75) and 1.088 ppb (95 % CI = 0.51-1.62), respectively. To our knowledge, this is a new finding. The findings pointed out that metagenomics profiling of fungi could enhance our understanding of a complex interrelation between rare and unculturable fungi with airway inflammation.

Indoor microbiome, microbial and plant metabolites, chemical compounds, and asthma symptoms in junior high school students: a multicentre association study in Malaysia.

BACKGROUND: Indoor microbial exposure is associated with asthma, but the health effects of indoor metabolites and chemicals have not been comprehensively assessed. METHODS: We collected classroom dust from 24 junior high schools in three geographically distanced areas in Malaysia (Johor Bahru, Terengganu and Penang), and conducted culture-independent high-throughput microbiome and untargeted metabolomics/chemical profiling. RESULTS: 1290 students were surveyed for asthma symptoms (wheeze). In each centre, we found significant variation in the prevalence of wheeze among schools, which could be explained by personal characteristics and air pollutants. Large-scale microbial variations were observed between the three centres; the potential protective bacteria were mainly from phyla Actinobacteria in Johor Bahru, Cyanobacteria in Terengganu and Proteobacteria in Penang. In total, 2633 metabolites and chemicals were characterised. Many metabolites were enriched in low-wheeze schools, including plant secondary metabolites flavonoids/isoflavonoids (isoliquiritigenin, formononetin, astragalin), indole and derivatives (indole, serotonin, 1H-indole-3-carboxaldehyde), and others (biotin, chavicol). A neural network analysis showed that the indole derivatives were co-occurring with the potential protective microbial taxa, including Actinomycetospora, Fischerella and Truepera, suggesting these microorganisms may pose health effects by releasing indole metabolites. A few synthetic chemicals were enriched in high-wheeze schools, including pesticides (2(3H)-benzothiazolethione), fragrances (2-aminobenzoic acid, isovaleric acid), detergents and plastics (phthalic acid), and industrial materials (4,4-sulfonyldiphenol). CONCLUSIONS: This is the first association study between high-throughput indoor chemical profiling and asthma symptoms. The consistent results from the three centres indicate that indoor metabolites/chemicals could be a better indicator than the indoor microbiome for environmental and health assessments, providing new insights for asthma prediction, prevention and control.

Evaluation of the Relationship between Fractional Exhaled Nitric Oxide (FeNO) with Indoor PM10, PM2.5 and NO2 in Suburban and Urban Schools.

Numerous epidemiological studies have evaluated the association of fractional exhaled nitric oxide (FeNO) and indoor air pollutants, but limited information available of the risks between schools located in suburban and urban areas. We therefore investigated the association of FeNO levels with indoor particulate matter (PM10 and PM2.5), and nitrogen dioxide (NO2) exposure in suburban and urban school areas. A comparative cross-sectional study was undertaken among secondary school students in eight schools located in the suburban and urban areas in the district of Hulu Langat, Selangor, Malaysia. A total of 470 school children (aged 14 years old) were randomly selected, their FeNO levels were measured, and allergic skin prick tests were conducted. The PM2.5, PM10, NO2, and carbon dioxide (CO2), temperature, and relative humidity were measured inside the classrooms. We found that the median of FeNO in the school children from urban areas (22.0 ppb, IQR = 32.0) were slightly higher as compared to the suburban group (19.5 ppb, IQR = 24.0). After adjustment of potential confounders, the two-level hierarchical multiple logistic regression models showed that the concentrations of PM2.5 were significantly associated with elevated of FeNO (>20 ppb) in school children from suburban (OR = 1.42, 95% CI = 1.17−1.72) and urban (OR = 1.30, 95% CI = 1.10−1.91) areas. Despite the concentrations of NO2 being below the local and international recommendation guidelines, NO2 was found to be significantly associated with the elevated FeNO levels among school children from suburban areas (OR = 1.11, 95% CI = 1.06−1.17). The findings of this study support the evidence of indoor pollutants in the school micro-environment associated with FeNO levels among school children from suburban and urban areas.

El Niño Southern Oscillation, monsoon anomaly, and childhood diarrheal disease morbidity in Nepal.

Climate change is adversely impacting the burden of diarrheal diseases. Despite significant reduction in global prevalence, diarrheal disease remains a leading cause of morbidity and mortality among young children in low- and middle-income countries. Previous studies have shown that diarrheal disease is associated with meteorological conditions but the role of large-scale climate phenomena such as El Niño-Southern Oscillation (ENSO) and monsoon anomaly is less understood. We obtained 13 years (2002-2014) of diarrheal disease data from Nepal and investigated how the disease rate is associated with phases of ENSO (El Niño, La Niña, vs. ENSO neutral) monsoon rainfall anomaly (below normal, above normal, vs. normal), and changes in timing of monsoon onset, and withdrawal (early, late, vs. normal). Monsoon season was associated with a 21% increase in diarrheal disease rates (Incident Rate Ratios [IRR]: 1.21; 95% CI: 1.16-1.27). El Niño was associated with an 8% reduction in risk while the La Niña was associated with a 32% increase in under-5 diarrheal disease rates. Likewise, higher-than-normal monsoon rainfall was associated with increased rates of diarrheal disease, with considerably higher rates observed in the mountain region (IRR 1.51, 95% CI: 1.19-1.92). Our findings suggest that under-5 diarrheal disease burden in Nepal is significantly influenced by ENSO and changes in seasonal monsoon dynamics. Since both ENSO phases and monsoon can be predicted with considerably longer lead time compared to weather, our findings will pave the way for the development of more effective early warning systems for climate sensitive infectious diseases.

Associations between the indoor microbiome, environmental characteristics and respiratory infections in junior high school students of Johor Bahru, Malaysia.

Pathogens are commonly present in the human respiratory tract, but symptoms are varied among individuals. The interactions between pathogens, commensal microorganisms and host immune systems are important in shaping the susceptibility, development and severity of respiratory diseases. Compared to the extensive studies on the human microbiota, few studies reported the association between indoor microbiome exposure and respiratory infections. In this study, 308 students from 21 classrooms were randomly selected to survey the occurrence of respiratory infections in junior high schools of Johor Bahru, Malaysia. Vacuum dust was collected from the floor, chairs and desks of these classrooms, and high-throughput amplicon sequencing (16S rRNA and ITS) and quantitative PCR were conducted to characterize the absolute concentration of the indoor microorganisms. Fifteen bacterial genera in the classes Actinobacteria, Alphaproteobacteria, and Cyanobacteria were protectively associated with respiratory infections (p < 0.01), and these bacteria were mainly derived from the outdoor environment. Previous studies also reported that outdoor environmental bacteria were protectively associated with chronic respiratory diseases, such as asthma, but the genera identified were different between acute and chronic respiratory diseases. Four fungal genera from Ascomycota, including Devriesia, Endocarpon, Sarcinomyces and an unclassified genus from Herpotrichillaceae, were protectively associated with respiratory infections (p < 0.01). House dust mite (HDM) allergens and outdoor NO2 concentration were associated with respiratory infections and infection-related microorganisms. A causal mediation analysis revealed that the health effects of HDM and NO2 were partially or fully mediated by the indoor microorganisms. This is the first study to explore the association between environmental characteristics, microbiome exposure and respiratory infections in a public indoor environment, expanding our understanding of the complex interactions among these factors.

Metagenomic characterization of indoor dust fungal associated with allergy and lung inflammation among school children.

The exposure of school children to indoor air pollutants has increased allergy and respiratory diseases. The objective of this study were to determine the toxicodynamic interaction of indoor pollutants exposure, biological and chemical with expression of adhesion molecules on eosinophil and neutrophil. A self-administered questionnaire, allergy skin test, and fractional exhaled nitric oxide (FeNO) analyser were used to collect information on health status, sensitization to allergens and respiratory inflammation, respectively among school children at age of 14 years. The sputum induced were analysed to determine the expression of CD11b, CD35, CD63 and CD66b on eosinophil and neutrophil by using flow cytometry technique. The particulate matter (PM2.5 and PM10), NO2, CO2, and formaldehyde, temperature, and relative humidity were measured inside the classrooms. The fungal DNA were extracted from settled dust collected from classrooms and evaluated using metagenomic techniques. We applied chemometric and regression in statistical analysis. A total of 1869 unique of operational taxonomic units (OTUs) of fungi were identified with dominated at genus level by Aspergillus (15.8%), Verrucoconiothyrium (5.5%), and Ganoderma (4.6%). Chemometric and regression results revealed that relative abundance of T. asahii were associated with down regulation of CD66b expressed on eosinophil, and elevation of FeNO levels in predicting asthmatic children with model accuracy of 63.6%. Meanwhile, upregulation of CD11b expressed on eosinophil were associated with relative abundance of A. clavatus and regulated by PM2.5. There were significant association of P. bandonii with upregulation of CD63 expressed on neutrophil and exposure to NO2. Our findings indicate that exposure to PM2.5, NO2, T. asahii, P.bandonii and A.clavatus are likely interrelated with upregulation of activation and degranulation markers on both eosinophil and neutrophil.

COVID-19 Epidemic in Malaysia: Epidemic Progression, Challenges, and Response.

COVID-19 pandemic is the greatest communicable disease outbreak to have hit Malaysia since the 1918 Spanish Flu which killed 34,644 people or 1% of the population of the then British Malaya. In 1999, the Nipah virus outbreak killed 105 Malaysians, while the SARS outbreak of 2003 claimed only 2 lives. The ongoing COVID-19 pandemic has so far claimed over 100 Malaysian lives. There were two waves of the COVID-19 cases in Malaysia. First wave of 22 cases occurred from January 25 to February 15 with no death and full recovery of all cases. The ongoing second wave, which commenced on February 27, presented cases in several clusters, the biggest of which was the Sri Petaling Tabligh cluster with an infection rate of 6.5%, and making up 47% of all cases in Malaysia. Subsequently, other clusters appeared from local mass gatherings and imported cases of Malaysians returning from overseas. Healthcare workers carry high risks of infection due to the daily exposure and management of COVID-19 in the hospitals. However, 70% of them were infected through community transmission and not while handling patients. In vulnerable groups, the incidence of COVID-19 cases was highest among the age group 55 to 64 years. In terms of fatalities, 63% were reported to be aged above 60 years, and 81% had chronic comorbidities such as diabetes, hypertension, and heart diseases. The predominant COVID-19 strain in Malaysia is strain B, which is found exclusively in East Asia. However, strain A, which is mostly found in the USA and Australia, and strain C in Europe were also present. To contain the epidemic, Malaysia implemented a Movement Control Order (MCO) beginning on March 18 in 4 phases over 2 months, ending on May 12. In terms of economic impacts, Malaysia lost RM2.4 billion a day during the MCO period, with an accumulated loss of RM63 billion up to the end of April. Since May 4, Malaysia has relaxed the MCO and opened up its economic sector to relieve its economic burden. Currently, the best approach to achieving herd immunity to COVID-19 is through vaccination rather than by acquiring it naturally. There are at least two candidate vaccines which have reached the final stage of human clinical trials. Malaysia's COVID-19 case fatality rate is lower than what it is globally; this is due to the successful implementation of early preparedness and planning, the public health and hospital system, comprehensive contact tracing, active case detection, and a strict enhanced MCO.

Asthma symptoms and respiratory infections in Malaysian students-associations with ethnicity and chemical exposure at home and school.

Little is known on respiratory effects of indoor chemicals in the tropics. We investigated associations between asthma and respiratory infections in Malaysian students and chemical exposure at home and at school. Moreover, we investigated differences in home environment between the three main ethnic groups in Malaysia (Malay, Chinese, Indian). Totally, 462 students from 8 junior high schools in Johor Bahru participated (96% participation rate). The students answered a questionnaire on health and home environment. Climate, carbon dioxide (CO2), volatile organic compounds (VOC), formaldehyde and nitrogen dioxide (NO2) were measured inside and outside the schools. Multilevel logistic regression was applied to study associations between exposure and health. Totally 4.8% were smokers, 10.3% had wheeze, 9.3% current asthma, and had 18.8% any respiratory infection in the past 3 months. Malay students had more dampness or mould (p < 0.001), more environmental tobacco smoke (ETS) (p < 0.001) and more cats (p < 0.001) at home as compared to Chinese or Indian students. Wheeze was associated with ethnicity (p = 0.02; lower in Indian), atopy (p = 0.002), current smoking (p = 0.02) and recent indoor painting at home (p = 0.03). Current asthma was associated with ethnicity (p = 0.001; lower in Chinese) and para-dichlorobenzene in classroom air (p = 0.008). Respiratory infections were related to atopy (p = 0.002), ethylbenzene (p = 0.02) and para-dichlorobenzene (p = 0.01) in classroom air. Para-dichlorobenzene is used in Asia against insects. In conclusion, chemical emissions from recent indoor painting at home can increase the risk of wheeze. In schools, para-dichlorobenzene can increase the risk of current asthma and respiratory infections while ethylbenzene can increase the risk of respiratory infections.

Particulate matter (PM2.5) as a potential SARS-CoV-2 carrier.

The rapid spread of the SARS-CoV-2 in the COVID-19 pandemic had raised questions on the route of transmission of this disease. Initial understanding was that transmission originated from respiratory droplets from an infected host to a susceptible host. However, indirect contact transmission of viable virus by fomites and through aerosols has also been suggested. Herein, we report the involvement of fine indoor air particulates with a diameter of ≤ 2.5 µm (PM2.5) as the virus's transport agent. PM2.5 was collected over four weeks during 48-h measurement intervals in four separate hospital wards containing different infected clusters in a teaching hospital in Kuala Lumpur, Malaysia. Our results indicated the highest SARS-CoV-2 RNA on PM2.5 in the ward with number of occupants. We suggest a link between the virus-laden PM2.5 and the ward's design. Patients' symptoms and numbers influence the number of airborne SARS-CoV-2 RNA with PM2.5 in an enclosed environment.

Association between indoor microbiome exposure and sick building syndrome (SBS) in junior high schools of Johor Bahru, Malaysia.

Sick building syndrome (SBS) is a collection of nonspecific syndromes linked with the built environment. The occurrence of SBS is associated with humidity, ventilation, moulds and microbial compounds exposure. However, no study has reported the association between indoor microbiome and SBS. In this study, 308 students were surveyed for SBS symptoms from 21 classrooms of 7 junior high schools from Johor Bahru, Malaysia, and vacuum dust from floor, desks and chairs was collected. High throughput amplicon sequencing (16S rRNA gene and ITS region) and quantitative PCR were conducted to characterize the absolute concentration of bacteria and fungi taxa. In total, 326 bacterial and 255 fungal genera were detected in dust with large compositional variation among classrooms. Also, half of these samples showed low compositional similarity to microbiome data deposited in the public database. The number of observed OTUs in Gammaproteobacteria was positively associated with SBS (p = 0.004). Eight microbial genera were associated with SBS (p < 0.01). Bacterial genera, Rhodomicrobium, Scytonema and Microcoleus, were protectively (negatively) associated with ocular and throat symptoms and tiredness, and Izhakiella and an unclassified genus from Euzebyaceae were positively associated with the throat and ocular symptoms. Three fungal genera, Polychaeton, Gympopus and an unclassified genus from Microbotryaceae, were mainly positively associated with tiredness. The associations differed with our previous study in microbial compounds (endotoxin and ergosterol) and SBS in the same population, in which nasal and dermal symptoms were affected. A higher indoor relative humidity and visible dampness or mould in classrooms were associated with a higher concentration of potential risk bacteria and a lower concentration of potential protective bacteria (p < 0.01). This is the first study to characterize the SBS-associated microorganisms in the indoor environment, revealing complex interactions between microbiome, SBS symptoms and environmental characteristics.

The Effects of Indoor Pollutants Exposure on Allergy and Lung Inflammation: An Activation State of Neutrophils and Eosinophils in Sputum.

BACKGROUND: To explore the inflammation phenotypes following indoor pollutants exposure based on marker expression on eosinophils and neutrophils with the application of chemometric analysis approaches. METHODS: A cross-sectional study was undertaken among secondary school students in eight suburban and urban schools in the district of Hulu Langat, Selangor, Malaysia. The survey was completed by 96 students at the age of 14 by using the International Study of Asthma and Allergies in Children (ISAAC) and European Community Respiratory Health Survey (ECRHS) questionnaires. The fractional exhaled nitric oxide (FeNO) was measured, and an allergic skin prick test and sputum induction were performed for all students. Induced sputum samples were analysed for the expression of CD11b, CD35, CD63, and CD66b on eosinophils and neutrophils by flow cytometry. The particulate matter (PM2.5 and PM10), NO2, CO2, and formaldehyde were measured inside the classrooms. RESULTS: Chemometric and regression results have clustered the expression of CD63 with PM2.5, CD11b with NO2, CD66b with FeNO levels, and CO2 with eosinophils, with the prediction accuracy of the models being 71.88%, 76.04%, and 76.04%, respectively. Meanwhile, for neutrophils, the CD63 and CD66b clustering with PM2.5 and CD11b with FeNO levels showed a model prediction accuracy of 72.92% and 71.88%, respectively. CONCLUSION: The findings indicated that the exposure to PM2.5 and NO2 was likely associated with the degranulation of eosinophils and neutrophils, following the activation mechanisms that led to the inflammatory reactions.

Indoor microbiome, environmental characteristics and asthma among junior high school students in Johor Bahru, Malaysia.

Indoor microbial diversity and composition are suggested to affect the prevalence and severity of asthma by previous home microbiome studies, but no microbiome-health association study has been conducted in a school environment, especially in tropical countries. In this study, we collected floor dust and environmental characteristics from 21 classrooms, and health data related to asthma symptoms from 309 students, in junior high schools in Johor Bahru, Malaysia. The bacterial and fungal composition was characterized by sequencing 16s rRNA gene and internal transcribed spacer (ITS) region, and the absolute microbial concentration was quantified by qPCR. In total, 326 bacterial and 255 fungal genera were characterized. Five bacterial (Sphingobium, Rhodomicrobium, Shimwellia, Solirubrobacter, Pleurocapsa) and two fungal (Torulaspora and Leptosphaeriaceae) taxa were protective for asthma severity. Two bacterial taxa, Izhakiella and Robinsoniella, were positively associated with asthma severity. Several protective bacterial taxa including Rhodomicrobium, Shimwellia and Sphingobium have been reported as protective microbes in previous studies, whereas other taxa were first time reported. Environmental characteristics, such as age of building, size of textile curtain per room volume, occurrence of cockroaches, concentration of house dust mite allergens transferred from homes by the occupants, were involved in shaping the overall microbial community but not asthma-associated taxa; whereas visible dampness and mold, which did not change the overall microbial community for floor dust, was negatively associated with the concentration of protective bacteria Rhodomicrobium (ß = -2.86, p = 0.021) of asthma. The result indicates complex interactions between microbes, environmental characteristics and asthma symptoms. Overall, this is the first indoor microbiome study to characterize the asthma-associated microbes and their environmental determinant in the tropical area, promoting the understanding of microbial exposure and respiratory health in this region.