Displaying publications 1 - 20 of 102 in total

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  1. Vinjamuri KS, Mhawish A, Banerjee T, Sorek-Hamer M, Broday DM, Mall RK, et al.
    Environ Pollut, 2020 Feb;257:113377.
    PMID: 31672363 DOI: 10.1016/j.envpol.2019.113377
    Attenuated backscatter profiles retrieved by the space borne active lidar CALIOP on-board CALIPSO satellite were used to measure the vertical distribution of smoke aerosols and to compare it against the ECMWF planetary boundary layer height (PBLH) over the smoke dominated region of Indo-Gangetic Plain (IGP), South Asia. Initially, the relative abundance of smoke aerosols was investigated considering multiple satellite retrieved aerosol optical properties. Only the upper IGP was selectively considered for CALIPSO retrieval based on prevalence of smoke aerosols. Smoke extinction was found to contribute 2-50% of the total aerosol extinction, with strong seasonal and altitudinal attributes. During winter (DJF), smoke aerosols contribute almost 50% of total aerosol extinction only near to the surface while in post-monsoon (ON) and monsoon (JJAS), relative contribution of smoke aerosols to total extinction was highest at about 8 km height. There was strong diurnal variation in smoke extinction, evident throughout the year, with frequent abundance of smoke particles at lower height (<4 km) during daytime compared to higher height during night (>4 km). Smoke injection height also varied considerably during rice (ON: 0.71 ± 0.65 km) and wheat (AM: 2.34 ± 1.34 km) residue burning period having a significant positive correlation with prevailing PBLH. Partitioning smoke AOD against PBLH into the free troposphere (FT) and boundary layer (BL) yield interesting results. BL contribute 36% (16%) of smoke AOD during daytime (nighttime) and the BL-FT distinction increased particularly at night. There was evidence that despite travelling efficiently to FT, major proportion of smoke AOD (50-80%) continue to remain close to the surface (<3 km) thereby, may have greater implications on regional climate, air quality, smoke transport and AOD-particulate modelling.
    Matched MeSH terms: Dust/analysis
  2. Ravindran B, Karmegam N, Awasthi MK, Chang SW, Selvi PK, Balachandar R, et al.
    Bioresour Technol, 2022 Feb;346:126442.
    PMID: 34848334 DOI: 10.1016/j.biortech.2021.126442
    The present study proposes a system for co-composting food waste and poultry manure amended with rice husk biochar at different doses (0, 3, 5, 10%, w/w), saw dust, and salts. The effect of rice husk biochar on the characteristics of final compost was evaluated through stabilization indices such as electrical conductivity, bulk density, total porosity, gaseous emissions and nitrogen conservation. Results indicated that when compared to control, the biochar amendment extended the thermophilic stage of the composting, accelerated the biodegradation and mineralization of substrate mixture and helped in the maturation of the end product. Carbon dioxide, methane and ammonia emissions were reduced and the nitrogen conservation was achieved at a greater level in the 10% (w/w) biochar amended treatments. This study implies that the biochar and salts addition for co-composting food waste and poultry manure is beneficial to enhance the property of the compost.
    Matched MeSH terms: Dust
  3. Siti Nur Haseela Izani, Anati Ali
    MATEMATIKA, 2019;35(2):187-200.
    MyJurnal
    The heat and mass transfer of steady magnetohydrodynamics of dusty Jeffrey fluid past an exponentially stretching sheet in the presence of thermal radiation have been investigated. The main purpose of this study is to conduct a detailed analysis of flow behaviour of suspended dust particles in non-Newtonian fluid. The governing equations hav been converted into dimensionless form, and then solved numerically via the Keller-box method. The expression of Sherwood number, Nusselt number and skin friction have been evaluated, and then displayed in tabular forms. Velocity, temperature and concentration profiles are presented graphically. It is observed that large value of dust particles mass concentration parameter has reduced the flow velocity significantly. Increase in radiation parameter enhances the temperature, whereas the increment in Schmidt number parameter reduces the concentration.
    Matched MeSH terms: Dust
  4. Othman M, Latif MT, Matsumi Y
    Ecotoxicol Environ Saf, 2019 Apr 15;170:739-749.
    PMID: 30583285 DOI: 10.1016/j.ecoenv.2018.12.042
    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 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.
    Matched MeSH terms: Dust/analysis*
  5. Shaharom S, Latif MT, Khan MF, Yusof SNM, Sulong NA, Wahid NBA, et al.
    Environ Sci Pollut Res Int, 2018 Sep;25(27):27074-27089.
    PMID: 30019134 DOI: 10.1007/s11356-018-2745-0
    This study aims to determine the concentrations of surfactants in the surface microlayer (SML), subsurface water (SSW) and fine mode aerosol (diameter size dust (23%) and sulphate/fresh sea salt (8%). During the southwest monsoon, the three main sources of atmospheric aerosol were biomass burning (71%), secondary inorganic aerosol (23%) and sea spray (6%). This study suggests anthropogenic sources are main contributors to the concentrations of surfactants in SML, SSW and fine aerosols.
    Matched MeSH terms: Dust/analysis
  6. Razak IS, Latif MT, Jaafar SA, Khan MF, Mushrifah I
    Environ Sci Pollut Res Int, 2015 Apr;22(8):6024-33.
    PMID: 25382497 DOI: 10.1007/s11356-014-3781-z
    This study was conducted to determine the composition of surfactants in atmospheric aerosols and rainwater in the vicinity of Lake Chini, Malaysia. Samples of atmospheric aerosol and rainwater were collected between March and September 2011 using a high volume air sampler (HVAS) and glass bottles equipped with funnel. Colorimetric analysis was undertaken to determine the concentration of anionic surfactants as methylene blue active substances (MBAS) and cationic surfactants as disulphine blue active substances (DBAS). The water-soluble ionic compositions were determined using inductively coupled plasma mass spectrometry for cations (Na, K, Mg and Ca) and ion chromatography equipped with a conductivity detector for anions (F(-), Cl(-), NO3(-), and SO4(2-)) and the Nessler Method was used to obtain the NH4(+) concentrations. The source apportionment of MBAS and DBAS in atmospheric aerosols was identified using a combination of principal component analysis (PCA) and multiple linear regression (MLR). The results revealed that the concentrations of surfactants in atmospheric aerosols and rainwater were dominated by anionic surfactants as MBAS. The concentration of surfactants as MBAS and DBAS was dominated in fine mode compared to coarse mode aerosols. Using PCA/MLR analysis, two major sources of atmospheric surfactants to Lake Chini were identified as soil dust (75 to 93%) and biomass burning (2 to 22%).
    Matched MeSH terms: Dust/analysis
  7. Praveena SM, Aris AZ
    Environ Geochem Health, 2018 Apr;40(2):749-762.
    PMID: 28929262 DOI: 10.1007/s10653-017-0021-8
    This study aims to determine the status of potentially toxic element concentrations of road dust in a medium-sized city (Rawang, Malaysia). This study adopts source identification via enrichment factor, Pearson correlation analysis, and Fourier spectral analysis to identify sources of potentially toxic element concentrations in road dust in Rawang City, Malaysia. Health risk assessment was conducted to determine potential health risks (carcinogenic and non-carcinogenic risks) among adults and children via multiple pathways (i.e., ingestion, dermal contact, and inhalation). Mean of potentially toxic element concentrations were found in the order of Pb > Zn > Cr(IV) > Cu > Ni > Cd > As > Co. Source identification revealed that Cu, Cd, Pb, Zn, Ni, and Cr(IV) are associated with anthropogenic sources in industrial and highly populated areas in northern and southern Rawang, cement factories in southern Rawang, as well as the rapid development and population growth in northwestern Rawang, which have resulted in high traffic congestion. Cobalt, Fe, and As are related to geological background and lithologies in Rawang. Pathway orders for both carcinogenic and non-carcinogenic risks are ingestion, dermal contact, and inhalation, involving adults and children. Non-carcinogenic health risks in adults were attributed to Cr(IV), Pb, and Cd, whereas Cu, Cd, Cr(IV), Pb, and Zn were found to have non-carcinogenic health risks for children. Cd, Cr(IV), Pb, and As may induce carcinogenic risks in adults and children, and the total lifetime cancer risk values exceeded incremental lifetime.
    Matched MeSH terms: Dust/analysis*; Industry
  8. Cui J, Cui J, Peng Y, Yao D, Chan A, Chen Z, et al.
    Sci Total Environ, 2020 Jun 27;744:140558.
    PMID: 32711301 DOI: 10.1016/j.scitotenv.2020.140558
    Fluxes and composition dynamics of atmospheric nitrogen deposition play key roles in better balancing economic development and ecological environment. However, there are some knowledge gaps and difficulties in urban ecosystems, especially for small and medium-sized cities. In this study, both flux and composition (ratio of NH4+-N to NO3--N, RN) of wet-deposited dissolved inorganic nitrogen (DIN, sum of NO3--N and NH4+-N) were estimated and sources were identified at a long-term urban observation station in Tongling, a typical medium-sized city in eastern China during 2010-2016, respectively. Results showed that wet-deposited DIN fluxes were 33.20 and 28.15 kgN ha-1 yr-1 in Tongling city during 2010-2011 and 2015-2016, respectively. Compared to these two periods, both DIN and NO3--N fluxes decreased by 15.2% and 31.8% for a series of NOx abatement measures applied effectively, respectively. At the same time, the NH4+-N flux remained stable and ranged from 19.53 to 20.62 kgN ha-1 yr-1, and the RN increased from 1.7 to 2.2. Seasonally, winds from the southwest and west-southwest with higher frequencies and speeds in spring and summer brought more NH4+-N and DIN wet deposition from an ammonia plant, which could threaten the safety of regional hydrosphere ecosystems. On the whole, the wet-deposited NH4+-N was threatening regional ecosystems of both the hydrosphere and forest. The wet-deposited DIN including NH4+-N in Tongling city stemmed mainly from a combined source of coal combustion and dust from Cu extraction and smelting, ammonia production, and roads. Therefore, production lines should be updated for Cu extraction and smelting industries, thermal power generations and the ammonia plant, old vehicles should be eliminated, and the use of new energy vehicles should be promoted for regional sustainable development and human health in the medium-sized city.
    Matched MeSH terms: Dust
  9. Ee-Ling O, Mustaffa NI, Amil N, Khan MF, Latif MT
    Bull Environ Contam Toxicol, 2015 Apr;94(4):537-42.
    PMID: 25652682 DOI: 10.1007/s00128-015-1477-9
    This study determined the source contribution of PM2.5 (particulate matter <2.5 μm) in air at three locations on the Malaysian Peninsula. PM2.5 samples were collected using a high volume sampler equipped with quartz filters. Ion chromatography was used to determine the ionic composition of the samples and inductively coupled plasma mass spectrometry was used to determine the concentrations of heavy metals. Principal component analysis with multilinear regressions were used to identify the possible sources of PM2.5. The range of PM2.5 was between 10 ± 3 and 30 ± 7 µg m(-3). Sulfate (SO4 (2-)) was the major ionic compound detected and zinc was found to dominate the heavy metals. Source apportionment analysis revealed that motor vehicle and soil dust dominated the composition of PM2.5 in the urban area. Domestic waste combustion dominated in the suburban area, while biomass burning dominated in the rural area.
    Matched MeSH terms: Dust/analysis
  10. Mohamad N, Latif MT, Khan MF
    Ecotoxicol Environ Saf, 2016 Feb;124:351-362.
    PMID: 26590697 DOI: 10.1016/j.ecoenv.2015.11.002
    This study aimed to investigate the chemical composition and potential sources of PM10 as well as assess the potential health hazards it posed to school children. PM10 samples were taken from classrooms at a school in Kuala Lumpur's city centre (S1) and one in the suburban city of Putrajaya (S2) over a period of eight hours using a low volume sampler (LVS). The composition of the major ions and trace metals in PM10 were then analysed using ion chromatography (IC) and inductively coupled plasma-mass spectrometry (ICP-MS), respectively. The results showed that the average PM10 concentration inside the classroom at the city centre school (82µg/m(3)) was higher than that from the suburban school (77µg/m(3)). Principal component analysis-absolute principal component scores (PCA-APCS) revealed that road dust was the major source of indoor PM10 at both school in the city centre (36%) and the suburban location (55%). The total hazard quotient (HQ) calculated, based on the formula suggested by the United States Environmental Protection Agency (USEPA), was found to be slightly higher than the acceptable level of 1, indicating that inhalation exposure to particle-bound non-carcinogenic metals of PM10, particularly Cr exposure by children and adults occupying the school environment, was far from negligible.
    Matched MeSH terms: Dust/analysis
  11. MANOHARAN A
    Med J Malaya, 1961 Mar;15:102-12.
    PMID: 14469397
    Matched MeSH terms: Dust*
  12. Chong KT, Wong SF, Mak JW, Loh LC, Ho TM
    Trop Biomed, 2015 Sep;32(3):524-39.
    PMID: 26695214 MyJurnal
    Allergens of Dermatophagoides and Blomia species are well-characterized but not for other species. This study was conducted to determine the prevalence of allergic sensitization to house dust (HDM) and storage mites (SM). One hundred adult subjects (aged ≥ 18) were recruited. The mite specific IgE of all allergic subjects were higher compared with healthy subjetcs despite being not statistically significant except for D. farinae and G. malaysiensis. The mean serum IgE levels against HDM and SM for allergic subjects were significantly higher compared with those in healthy subjects. They were mainly sensitized to Dermatophagoides farinae (35%) and Glycycometus malaysiensis (37%). Immunoblots revealed not all allergic subjects showed positive immuno-reactivity against the mites tested. Single or multiple bands were observed for different species. The subjects were commonly sensitized to Group 2 (9-12 kDa), 10 (38 kDa) and 18 (40-48 kDa) allergens. Twenty-one out of 60 allergic subjects were sensitized to either one or more species. The majority of them (71%) were sensitized to single species. The allergic subjects were mainly sensitized to D. pteronyssinus, followed by Tyrophagus putrecentiae and Aleuroglyphus ovatus. Seven were solely sensitized to HDM while 10 were solely sensitized to SM. Four subjects were sensitized to both. Pre-adsorption study revealed no cross-reactivity. There was difference between the prevalence and reactivity to allergens of HDM and SM in these subjects. Both ELISA and immunoblot did not correlate well but can complement each other in improving the detection of mite allergens to the species level.
    Matched MeSH terms: Dust/immunology*
  13. SOBIRATUL NADIA ABDULLAH, NOOR ZAITUN YAHAYA, WAN RAFIZAH WAN WAN ABDULLAH
    MyJurnal
    The concentrations of airborne particulate matter (PM) is often measured as a mass concentration. However, the other way to express particulate matter is by using the Particle Number Count ([PNC]) concentrations. This study aims to analyse the seasonal variation of airborne particulate matter in terms of [PNC] by using R packages and the Boosted Regression Trees (BRTs) technique. The study was conducted at IOES, Universiti of Malaya in Bachok, Kelantan. The monitoring was important to understand the variability of seasonal effects due to different seasons. In this work, only the datasets for three seasons (Inter Monsoon, North East Monsoon and South-West Monsoon) were analysed involving 25,958 data. The air quality monitoring equipment involved was the particle counter Environment Dust Monitor GRIMM Model 180 and a weather station for recording the meteorological parameters. The data analysis was completed by using R software and its package for evaluating seasonal variability and providing the statistical analysis. The relationship between variables was studied by using the Boosted Regression Tree (BRT) technique. The interaction between independent variables towards the [PNC] in different seasons was discussed. The best setting result of BRT model evaluation R² is 0.22 (North-East Monsoon), 0.87 (Intern monsoon 1), and 0.59 for South West Monsoon which indicated that the model developed is acceptable except for NEM and intern monsoon seasons. Temperature (57 %) and wind direction (67%) were found to be the highest factor influenced by the formation of [PNC] concentrations in this area. Finally, good results indicated that BRT technique is an acceptable way to analysed air pollution data.
    Matched MeSH terms: Dust
  14. Ahmad A, Rafatullah M, Sulaiman O, Ibrahim MH, Hashim R
    J Hazard Mater, 2009 Oct 15;170(1):357-65.
    PMID: 19464117 DOI: 10.1016/j.jhazmat.2009.04.087
    Meranti (Philippine mahogany) sawdust, an inexpensive material, showed strong scavenging behaviour through adsorption for the removal of methylene blue (MB) from aqueous solution. Batch studies were performed to evaluate and optimize the effects of various parameters such as contact time, pH, initial dye concentrations and adsorbent dosage. Langmuir, Freundlich and Temkin isotherms were used to analyze the equilibrium data at different temperatures. The experimental data fitted well with the Langmuir adsorption isotherm, indicating thereby the mono layer adsorption of the dye. The monolayer sorption capacity of meranti sawdust for MB was found to be 120.48, 117.64, 149.25 and 158.73 mg/g at 30, 40, 50 and 60 degrees C, respectively. Thermodynamic calculations showed that the MB adsorption process is endothermic and spontaneous in nature. Kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model. The results indicated that the meranti sawdust could be an alternative material in place of more costly adsorbents used for dye removal.
    Matched MeSH terms: Dust
  15. Mariana A, Santhana Raj AS, Tan SN, Ho TM
    Trop Biomed, 2007 Dec;24(2):29-37.
    PMID: 18209705
    Many finer taxonomic characters of Blomia tropicalis are not distinctly visible under conventional light microscopy. Scanning electron micrographs of this mite are therefore presented in this paper for better appreciation of the inconspicuous features of the morphology of the species. The differences in morphology of male and female B. tropicalis are also briefly discussed.
    Matched MeSH terms: Dust
  16. Norbäck D, Hashim JH, Cai GH, Hashim Z, Ali F, Bloom E, et al.
    PLoS One, 2016;11(2):e0147996.
    PMID: 26829324 DOI: 10.1371/journal.pone.0147996
    There are few studies on rhinitis and sick building syndrome (SBS) among students in tropical countries. We studied associations between levels of five fungal DNA sequences, two mycotoxins (sterigmatocystin and verrucarol) and cat allergen (Fel d 1) levels in schools and rhinitis and other weekly SBS symptoms in the students. Fungal DNA was measured by quantitative PCR and cat allergen by ELISA. Pupils (N = 462) from eight randomly selected schools in Johor Bahru, Malaysia participated (96%). Dust samples were collected by cotton swabs and Petri dishes exposed for one week. None of the schools had a mechanical ventilation system, but all classrooms had openable windows that were kept open during lectures and indoor CO2 levels were low (mean 492 ppm; range 380-690 ppm). Weekly nasal symptoms (rhinitis) (18.8%), ocular (11.6%), throat (11.1%), dermal symptoms, headache (20.6%) and tiredness (22.1%) were common. Total fungal DNA in swab samples was associated with rhinitis (p = 0.02), ocular symptoms (p = 0.009) and tiredness (p = 0.001). There were positive associations between Aspergillus versicolor DNA in Petri dish samples, ocular symptoms (p = 0.02) and tiredness (p = 0.001). The level of the mycotoxin verrucarol (produced by Stachybotrys chartarum) in swab samples was positively associated with tiredness (p = 0.04). Streptomyces DNA in swab samples (p = 0.03) and Petri dish samples (p = 0.03) were negatively associated with tiredness. In conclusion, total fungal contamination, measured as total fungal DNA) in the classrooms, Aspergillus versicolor and verrucarol can be risk factors for rhinitis and SBS symptoms among students in the tropical country Malaysia.
    Matched MeSH terms: Dust/analysis*
  17. Dewika M, Markandan K, Irfan NA, Mohd Abdah MAA, Ruwaida JN, Sara YY, et al.
    Chemosphere, 2023 May;324:138270.
    PMID: 36878370 DOI: 10.1016/j.chemosphere.2023.138270
    The emergence of microplastics (MPs) pollution as a global environmental concern has attracted significant attention in the last decade. The majority of the human population spends most of their time indoors, leading to increased exposure to MPs contamination through various sources such as settled dust, air, drinking water and food. Although research on indoor MPs has intensified significantly in recent years, comprehensive reviews on this topic remain limited. Therefore, this review comprehensively analyses the occurrence, distribution, human exposure, potential health impact and mitigation strategies of MPs in the indoor air environment. Specifically, we focus on the risks associated with finer MPs that can translocate into the circulatory system and other organs, emphasizing the need for continued research to develop effective strategies to mitigate the risks associated with MPs exposure. Our findings suggest that indoor MPs impose potential risk to human health, and strategies for mitigating exposure should be further explored.
    Matched MeSH terms: Dust/analysis
  18. Ibrahim Zubil, AR., Wan Adnan W. A
    MyJurnal
    Occupational health hazards as a result to exposure to mineral dust containing silica has been established long time ago in occupational health history. Its effects on lung function and symptom was evaluated in a cross sectional studied among 49 small enterprise pottery workers in the county of Sayong clustered in 3 villages. Respiratory symptoms and lung function was evaluated using MRC respiratory questionnaire 86 and standard spirometry performed. The prevalence of chronic cough, phlegm and chest tightness was 24.5%, 16% and16% respectively. There was no significant decrement in lung function parameters from the predicted normal value with the mean predicted FVC; FEV1 and FEV1/FVC ratio was 85.32%, 83.87% and 99.22 respectively. The relationship between lung symptoms and lung function parameters was evaluated and the result was not significant.
    Matched MeSH terms: Dust
  19. Nurul, A.H., Shamsul Bahri, M.T., Noor Hassim, I.
    MyJurnal
    A cross sectional study was carried out to determine the relationship between dust exposure and pulmonary function in male steel workers in Terengganu, Malaysia. The investigation included spirometric testing and detailed personal interviews using a structured questionnaire adopted from British Medical Research Council (BRMC) Questionnaire on respiratory symptoms. Respiratory symptoms commonly reported by the male workers were morning phlegm (33.1%), shortness of breath (31.9%), chest tightness (30.4%), and morning cough (17.8%). Age and duration of employment were among the factors associated with respiratory symptoms (p
    Matched MeSH terms: Dust
  20. Razlan Musa, Lin Naing, Zulkifli Ahmad, Rusli Nordin
    MyJurnal
    The relationship between dust exposure and lung function were investigated in a cross-sectional study of 70 male quarry workers. The investigation included spirometric testing and detailed personal interviews using a structured questionnaire adapted from British Medical Research Council questionnaire on respiratory symptoms. Respiratory symptoms commonly reported by the male workers were shortness of breath (42.9%), chest tightness (37.1 %}, morning phlegm (20.0%) and morning cough (0.8%}. Prevalence of respiratory symptoms was greater in current smokers. Age and duration of employment also had significant relationship with chest tightness. Both FEV, and FVC of these workers were significantly reduced when compared to healthy population. Smoking status, age, and duration of employment were also associated with reduced pulmonary function (p<0.01).
    Key words: respiratory symptoms, lung function and quarry workers
    Matched MeSH terms: Dust
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