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Volatile organic compounds (VOCs) affect oxidant loadings and secondary organic aerosol formation in the lower atmosphere. The marine environment is thought to be an important global source of biog...

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.

To understand the characteristics of particulate matter (PM) in the Southeast Asia region, the spatial-temporal concentrations of PM

Good indoor air quality (IAQ) is essential to ensure students’ and teachers’ improved performance and productivity. This study aimed to investigate particulate matter (PM) concentration with different sizes in a classroom during haze episode and to evaluate the health effect of air pollution during haze to the school student in Malaysia. The particulate matter concentration with aerodynamic diameter size less than 10 µm (PM10) was collected for 8 h using a low volume air sampler (LVS) equipped with quartz filter paper. The trace metals element (Pb, Cd, Co, Ni, Cr, Mn, As and Cu) in PM10 was analysed using inductively coupled plasma mass spectrometry (ICP-MS). Simultaneously, PM concentration in real time at differences sizes (PM10, PM2.5 and PM1) was also collected using Grimm aerosol spectrometer with 1-min interval. A questionnaire survey on school children’s health condition and the lung function test using spirometry were also performed. The results show that there was no significant difference in PM10 concentration during haze (95 ± 25 μg m−3). The dominant trace metal concentrations in PM10 were Mn and Cr both during haze. The mean concentrations of continuous monitoring of PM10, PM2.5 and PM1 during haze event were 85 ± 14 μg m−3, 68 ± 16 μg m−3 and 61 ± 16 μg m−3. The mean forced expiratory volume in the first second (FEV1) and the mean forced vital capacity (FVC) value during haze were 97.7% and 91.8%. The health risk assessment of school children on trace metals in PM10 via inhalation was higher than the acceptable value with a total hazard quotient (HQ) more than 1.0 for both hazes. For carcinogenic elements, the excess lifetime cancer risk (ELCR) was higher than the acceptable limit for haze event with a value of 3.4XE-05. This study found that the impact of haze pollution on indoor PM10 concentration was relatively low; however, there was still a high exposure of school children to the carcinogenic and non-carcinogenic elements during haze event.

Globally, the COVID-19 pandemic has had both positive and negative impacts on humans and the environment. In general, a positive impact can be seen on the environment, especially in regard to air quality. This positive impact on air quality around the world is a result of movement control orders (MCO) or lockdowns, which were carried out to reduce the cases of COVID-19 around the world. Nevertheless, data on the effects on air quality both during and post lockdown at local scales are still sparse. Here, we investigate changes in air quality during normal days, the MCOs (MCO 1, 2 and 3) and post MCOs, namely the Conditional Movement Control Order (CMCO) and the Recovery Movement Control Order (RMCO) in the Klang Valley region. In this study, we used the air sensor network AiRBOXSense that measures carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2) and particulate matter (PM2.5 and PM10) at Petaling Jaya South (PJS), Kelana Jaya (KJ) and Kota Damansara (KD). The results showed that the daily average concentrations of CO and NO2 mostly decreased in the order of normal days &gt, MCO (MCO 1, 2 and 3) &gt, CMCO &gt, RMCO. PM10, PM2.5, SO2 and O3 showed a decrease from the MCO to RMCO. PJS showed that air pollutant concentrations decreased from normal days to the lockdown phases. This clearly shows the effects of ‘work from home’ orders at all places in the PJS city. The greatest percentage reductions in air pollutants were observed during the change from normal days to MCO 1 (24% to 64%), while during MCO 1 to MCO 2, the concentrations were slightly increased during the changes of the lockdown phase, except for SO2 and NO2 over PJS. In KJ, most of the air pollutants decreased from MCO 1 to MCO 3 except for CO. However, the percentage reduction and increments of the gas pollutants were not consistent during the different phases of lockdown, and this effect was due to the sensor location—only 20 m from the main highway (vehicle emissions). The patterns of air pollutant concentrations over the KD site were similar to the PJS site, however, the percentage reduction and increases of PM2.5, O3, SO2 and CO were not consistent. We believe that local burning was the main contribution to these unstable patterns during the lockdown period. The cause of these different changes in concentrations may be due to the relaxation phases during the lockdown at each station, where most of the common activities, such as commuting and industrial activities changed in frequency from the MCO, CMCO and RMCO. Wind direction also affected the concentrations, for example, during the CMCO and RMCO, most of the pollutants were blowing in from the Southeast region, which mostly consists of a city center and industrial areas. There was a weak correlation between air pollutants and the temperature and relative humidity at all stations. Health risk assessment analysis showed that non-carcinogenic risk health quotient (HQ) values for the pollutants at all stations were less than 1, suggesting unlikely non-carcinogenic effects, except for SO2 (HQ &gt, 1) in KJ. The air quality information showed that reductions in air pollutants can be achieved if traffic and industry emissions are strictly controlled.

Volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene and xylene (BTEX) are air pollutants that harm human health. This study aims to identify BTEX concentrations before the lockdown known as the Movement Control Order was imposed (BMCO), during the implementation of the Movement Control Order (MCO), and then during the Conditional Movement Control Order (CMCO). These orders were introduced during the COVID-19 pandemic in Malaysia. The study utilised data measured by the continuous monitoring of BTEX using online gas chromatography instruments located at three urban area stations. The results showed that the BTEX concentrations reduced by between -38% and -46% during the MCO compared to the BMCO period. The reduction of human mobility during the MCO and CMCO influenced the lower BTEX concentrations recorded at a station within the Kuala Lumpur area. The results of the BTEX diagnostic ratios and principal component analysis showed that the major source of BTEX, especially during the BMCO and CMCO periods, was motor vehicle emissions. Further investigation, using correlation analysis and polar plots, showed that the BTEX concentrations were also influenced by meteorological variables such as wind speed, air temperature and relative humidity.

Volatile organic compounds (VOCs) form ozone (O

Benzene, toluene, ethylbenzene, m,p-xylene, and o-xylene (collectively referred to as BTEX), which are prevalent in the ambient air of urban environments, potentially cause chronic health effects, particularly among outdoor workers. Aim of this study was to evaluate BTEX concentrations in the Klang Valley of Malaysia and assess the health risks to urban traffic police officers, whose duties include controlling the traffic flow and enforcing traffic laws. Air samples were collected with low-flow personal samplers during the officers’ work shifts outdoors, and the BTEX content was then analyzed via gas chromatography-mass spectrometry (GC-MS) coupled with thermal desorption (TD). A probabilistic method based on Monte Carlo simulation was applied to determine the cancer risk (CR) and hazard quotient (HQ), and a sensitivity analysis was performed to identify the greatest contributors to the estimated risks. The total BTEX concentration in the samples averaged 211.83 µg m–3, with the largest component being toluene (averaging 89.08 µg m–3 in concentration), followed by m,p-xylene (37.25 µg m–3), o-xylene (35.80 µg m–3), benzene (25.82 µg m–3), and ethylbenzene (23.89 µg m–3). The average CR value for benzene (5.31 × 10–6) as well as the 95th percentiles of the CR values for benzene and ethylbenzene (1.70 × 10–5 and 2.12 × 10–6, respectively) exceeded the acceptable level of exposure (1.0 × 10–6). The HQ values for all of the BTEX species were less than one. The sensitivity analysis revealed that the most influential parameter in increasing the estimated CR and HQ was the exposure duration, followed by the BTEX concentration. The estimated CR indicates that the prolonged exposure to benzene and ethylbenzene experienced by traffic police officers exacerbates the risk of adverse health effects. These results, which provide baseline data for determining the occupational risk to individuals who are exposed to BTEX while working on or near a road, emphasize the need for additional regulations, including the use of appropriate respiratory protective equipment.

The world is currently going through the COVID-19 pandemic which has caused hundreds of thousands of deaths in just a few months. Considering the need for lockdown measures, most countries, including Malaysia, have implemented ‘Movement Control Orders’ (MCOs) as a prevention step to reduce the deadly spread of this disease. Local and worldwide media have reported the immediate improvement of air quality due to this event. Nevertheless, data on the effects of MCOs on air quality at local scales are still sparse. Here, we investigate changes in air quality during the MCO at an urban area using the air sensor network AiRBOXSense which measures monoxide (CO) and particulate matter (PM2.5 and PM10). In this study, air pollutant data during normal days were compared with MCO days using a reference analyser and AiRBOXSense. The results showed that the levels of the measured pollutants dropped by ~20 to 60% during the MCO days at most locations. However, CO in Kota Damansara (KD) dropped to 48.7%, but PM2.5 and PM10 increased up to 60% and 9.7% respectively during MCO days. Local burning activities in the residential area of KD are believed to be the main cause of the increased PM levels. This study has proven that air pollutant levels have significantly fallen due to the MCO. This air quality level information showed that the reduction of air pollutants can be achieved if traffic and industry emissions are strictly controlled.

The Electric Field and Voltage Distribution (EFVD) are an important parameter for assessing high voltage bushing transformer performance. However, conducting laboratories experiment is dangerous, difficult and expensive due to several aspects. Therefore, Finite Element Method (FEM) software is the best option used as a tool for the assessment of bushing transformer's performance in terms of EFVD. But, before an assessment of analysis could be carried out, an accurate model of bushing transformer must first to be designed. In this research, Computer Aided Design (CAD) software has been employed to design the 145kV bushing transformer based on actual dimension. Upon completion, the design has been exported to FEM software for further analysis. In FEM software, measurement and analysis of electric field and voltage distribution (EFVD) have been carried out. The measurements are performed at various locations of bushing transformer such as of the porcelain surface (both air and oil side), along with aluminum foils, and at oil-impregnated paper (OIP). The results obtained have been compared with other researchers and it is found very satisfactory.

Isoprene (C5H8) plays an important role in the formation of surface ozone (O3) and the secondary organic aerosol (SOA) which contributed to the climate change. This study aims to determine hourly distribution of tropospheric isoprene over the Western Coast of Antarctic Peninsula (WCAP) during the Malaysian Antarctic Scientific Expedition Cruise 2016 (MASEC′16). In-situ measurements of isoprene were taken using a custom-built gas chromatography with photoionization detector, known as iDirac. Biological parameters such as chlorophyll a (chl-a) and particulate organic carbon (POC) were compared to the in-situ isoprene measurements. Significant positive correlation was observed between isoprene and POC concentrations (r2 = 0.67, p

This study aims to determine the trends of volatile organic compound (VOC) concentrations and their potential contribution to O

The COVID-19 pandemic has plunged the world into uncharted territory, leaving people feeling helpless in the face of an invisible threat of unknown duration that could adversely impact the national economic growths. According to the World Health Organization (WHO), the SARS-CoV-2 spreads primarily through droplets of saliva or discharge from the mouth or nose when an infected person coughs or sneezes. However, the transmission of the SARS-CoV-2 through aerosols remains unclear. In this study, computational fluid dynamic (CFD) is used to complement the investigation of the SARS-CoV-2 transmission through aerosol. The Lagrangian particle tracking method was used to analyze the dispersion of the exhaled particles from a SARS-CoV-2-positive patient under different exhale activities and different flow rates of chilled (cooling) air supply. Air sampling of the SARS-CoV-2 patient ward was conducted for 48-h measurement intervals to collect the indoor air sample for particulate with diameter less than 2.5 μm. Then, the reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) was conducted to analyze the collected air sample. The simulation demonstrated that the aerosol transmission of the SARS-CoV-2 virus in an enclosed room (such as a hospital ward) is highly possible.

Background: Biogenic Volatile Organic Compounds (BVOCs) such as isoprene (C5H8) are ozone (O3) precursors that can be emitted at significant concentrations from the oil palm tree (Elaeis guineensis). Reactions involving BVOCs can lead to increased levels of surface O3 which can significantly impair air quality and cause crop damage. This study focuses on the link between isoprene, surface O3 and carbon dioxide (CO2) over an oil palm plantation and the effects of meteorological factors such as temperature and irradiance on the gas concentrations. The mixing ratios of isoprene, surface O3 and CO2 were measured using a portable gas chromatograph with a photoionization detector called ‘iDirac’, an EcoTech O3 analyser, and LI-COR, respectively. Atmospheric models were used for measured selected gases estimation and validation purposes.Results: Results showed that isoprene and surface O3 had maximum daytime mixing ratios of ~25 ppb and ~57 ppb, respectively. CO2 mixing ratios were high during the night compared to the day, with a maximum night-time ratio of ~883 ppm. It is also showed that suppression of isoprene emissions from plants by high CO2 concentrations during the night was due to the reduction of dimethylallyl diphosphate (DMADP) in the leaf cells. The meteorological parameters temperature and light intensity were significantly correlated with isoprene and surface O3, with r2=0.91 and p2=0.87 and p-2 h-1 which are higher than previous studies on pristine forest. This information together with the the in-situ measurement information on isoprene emission flux is then fed into the WRF-CMAQ atmospheric chemistry model to study the effect of oil palm plantation expansion over the years (2000 – 2016) on the local atmospheric chemistry.Conclusions: The in-situ of isoprene measurement in oil palm plantation has provided the variations of atmospheric concentration at different time scale which is important in giving information of surface O3 production. The relationship between isoprene-surface O3 and CO2-isoprene were interconnected at different time and influenced by meteorological factors. The model has discovered regions that are converted into oil palm plantation has experienced rise in isoprene concentration in region that are converted into oil palm plantation, and it even can be carried downwind up to 100 km inland of the emission source.

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 droplet 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 particulate with the diameter of ≤ 2.5 µm (PM2.5) as the transport agent of the virus. PM2.5 was collected over four weeks during a 48 hours measurement intervals in four separate wards containing different infected clusters in a teaching hospital in Kuala Lumpur, Malaysia. Our results indicated highest SARS-CoV-2 RNA on PM2.5 in the ward associated with a lavatory. We suggest a link between the virus-laden PM2.5 and the ward’s design. Patients’ symptoms and numbers that govern the magnitude of viral shedding may also influence the number of airborne SARS-CoV-2 RNA on PM2.5 in an enclosed environment.

Volatile organic compounds such as benzene, toluene, ethylbenzene, xylene (BTEX), and particulate matter (PM) with a diameter of less than 2.5 microns (PM2.5) are often associated with traffic-related air pollution (TRAP) and harm the health of the community. This study aimed to evaluate the personal air pollutant exposure, micronucleus (MN) frequency, and respiratory health symptoms among 160 traffic policemen and 149 office workers in Klang Valley. Personal exposure concentrations for BTEX and PM2.5 among traffic police were 390.12 μg/m3 and 140.00 μg/m3 respectively, whereas 97.64 μg/m3 (BTEX) and 23.00 µg/m3 (PM2.5) among office workers. Statistical analysis for MN frequency between traffic policemen (6.2±2.6) and office workers (3.0±2.0) shows a significant difference (p < 0.001). The Chi-Square test for respiratory health symptoms indicates that only cough shows the significant differences between traffic policemen and office workers (χ2 = 5.645, p = 0.018, PR = 1.800). In short, this study showed that TRAP exposure would increase the chromosomal damage that can cause high MN frequency among traffic policemen and would increase the prevalence of respiratory health symptoms among urban workers.

This study aimed to determine the spatial distribution of PM2.5 and PM10 collected in four regions (North, Central, South and East Coast) of Peninsular Malaysia during the southwest monsoon. Concurrent measurements of PM2.5 and PM10 were performed using a high volume sampler (HVS) for 24 h (August to September 2018) collecting a total of 104 samples. All samples were then analysed for water soluble inorganic ions (WSII) using ion chromatography, trace metals using inductively coupled plasma-mass spectroscopy (ICP-MS) and polycyclic aromatic hydrocarbon (PAHs) using gas chromatography-mass spectroscopy (GC-MS). The results showed that the highest average PM2.5 concentration during the sampling campaign was in the North region (33.2 ± 5.3 μg m−3) while for PM10 the highest was in the Central region (38.6 ± 7.70 μg m−3). WSII recorded contributions of 22% for PM2.5 and 20% for PM10 mass, with SO42− the most abundant species with average concentrations of 1.83 ± 0.42 μg m−3 (PM2.5) and 2.19 ± 0.27 μg m−3 (PM10). Using a Positive Matrix Factorization (PMF) model, soil fertilizer (23%) was identified as the major source of PM2.5 while industrial activity (25%) was identified as the major source of PM10. Overall, the studied metals had hazard quotients (HQ) value of

Benzene, toluene, ethylbenzene and xylene isomers (BTEX) are volatile organic air pollutants of concern which arise from natural and anthropogenic sources. This study aims to determine and evaluate the BTEX levels in ambient air in selected areas of Malaysia, namely: Kuala Lumpur (KL-urban), Penang (PG-urban), Bangi (BG-suburban), Langkawi (LGK-suburban) and the Danum Valley (DV-rural). Active sampling with sorbent tubes was applied in this study and samples were analysed using thermal desorption (TD) coupled with gas chromatography-mass spectrometry (GC-MS). The results show that the urban area of KL had the highest ΣBTEX (40.36 ± 6.99 μg/m3) followed by PG (30.82 ± 8.06 μg/m3). ΣBTEX concentrations in the suburban areas of LGK and BG were measured as 20.22 ± 11.42 μg/m3 and 12.36 ± 2.26 μg/m3, respectively. The rural area of DV had the lowest concentration of ΣBTEX (5.55 ± 2.54 μg/m3). The average toluene to benzene (T:B) ratio at KL, PG and LG were found to be within the range of 2.00–5.00 thus indicating vehicle emissions as the main source. The benzene level at both KL (7.43 μg/m3) and PG (5.12 μg/m3) were found to be slightly higher than the annual benchmark of 5 μg/m3 as suggested by the European Union (EU). The results of health risk assessments found that the cancer risk (CR) based on benzene concentrations in urban, suburban and rural areas was > 10−6 thus indicating a link between human cancer risks and ambient benzene exposure.

This study aims to determine the inorganic and carbonaceous components depending on the seasonal variation and size distribution of urban air particles in Kuala Lumpur. Different fractions of particulate matter (PM) were measured using a Nanosampler from 17 February 2017 until 27 November 2017. The water-soluble inorganic ions (WSIIs) and carbonaceous components in all samples were analysed using ion chromatography and carbon analyser thermal/optical reflectance, respectively. Total PM concentration reached its peak during the southwest (SW) season (70.99 ± 6.04 μg/m3), and the greatest accumulation were observed at PM0.5–1.0 (22%–30%, 9.55 ± 1.03 μg/m3) and PM2.5–10 (22%–25%, 10.34 ± 0.81 μg/m3). SO42−, NO3− and NH4+ were major contributors of WSIIs, and their formation was favoured mainly during SW season (80.5% of total ions). PM0.5–1.0 and PM2.5–10 exhibited the highest percentage of WSII size distribution, accounted for 28.4% and 13.5% of the total mass, respectively. The average contribution of carbonaceous species (OC + EC) to total carbonaceous concentrations were higher in PM0.5–1.0 (35.2%) and PM2.5–10 (26.6%). Ultrafine particles (PM

The water stream has been reported to contain non-steroidal anti-inflammatory drugs (NSAIDs), released from households and premises through discharge from Sewage Treatment Plant (STP). This research identifies commonly consumed NSAIDs namely ibuprofen (IBU), diclofenac (DIC), ketoprofen (KET) and naproxen (NAP) in the influent wastewater from two urban catchments (i.e. 2 STPs). We expand our focus to assess the efficiency of monomer (C18) and dimer (HLB) types of sorbents in the solid phase extraction method followed by gas chromatography mass spectrometry (GCMS) analysis and optimize model prediction of NSAIDs in the influent wastewater using I-Optimal design. The ecological risk assessment of the NSAIDs was evaluated. The HLB produced reliable analysis for all NSAIDs under study (STP1: 6.7 × 10−3 mg L−1 to 2.21 × 10−1 mg L−1, STP2: 1.40 × 10−4 mg L−1 to 9.72 × 10−2 mg L−1). The C18 however, selective to NAP. Based on the Pearson proximity matrices, the DICHLB can be a good indicator for IBUHLB (0.565), NAPC18 (0.721), NAPHLB (0.566), and KETHLB (0.747). The optimized model prediction for KET and NAP based on DIC are successfully validated. The risk quotients (RQ) values of NSAIDs were classified as high (RQ > 1), medium (RQ, 0.1–1) and low (RQ, 0.01–0.1) risks. The optimized models are beneficial for major NSAIDs (KET and NAP) monitoring in the influent wastewater of urban domestic area. An upgrade on the existing wastewater treatment infrastructure is recommended to counteract current water security situation.

The present work determines the temporal and size distribution of polycyclic aromatic hydrocarbons (PAHs) concentrations in tropical urban air in Kuala Lumpur, Malaysia. Particulate matter (PM) fractions were assessed using a nanosampler in accordance with the seasonal cycle in Malaysia. The 16 USEPA priority PAHs were analyzed by gas chromatography mass spectrometry (GC–MS). The health risks were quantitatively determined the exposure risk of two selected population groups based on incremental lifetime cancer risks (ILCRs). Results indicate that ∑16PAH concentration was highest during the southwest (SW) monsoon (15.8 ng m−3). The high molecular weights of PAHs dominated 65% to 85% of the total PAH. Approximately 71.7% to 80.7% of indeno(1,2,3-cd)pyrene, dibenzo(a,h)anthracene, and benzo(g,h,i)perylene were concentrated as fine particles (PM0.1–0.5, PM0.5–1.0, and PM1.0–2.5), and unimodally during the SW monsoon. Principal component analysis (PCA) and positive matrix factorization (PMF) determined that the PAH have originated mainly from vehicles and engines emission with 24.7% and 23.7%, respectively. The total percentage of benzo(a)pyrene equivalent (BaPeq) concentration in the PM

Volatile organic compounds (VOCs) are widely recognized to affect the environment and human health. This review provides a comprehensive presentation of the types and levels of VOCs, their sources and potential effects on human health and the environment based on past and current observations made at tropical sites. Isoprene was found to be the dominant biogenic VOC in the tropics. Tropical broad leaf evergreen trees are the main emitters of isoprene, making up more than 70% of the total emissions. The VOCs found in the tropical remote marine atmosphere included isoprene (>100 ppt), dimethyl sulfide (≤100 ppt) and halocarbons, i.e. bromoform (≤8.4 ppt), dibromomethane (≤2.7 ppt) and dibromochloromethane (≤1.6 ppt). VOCs such as benzene, toluene, ethylbenzene and xylene (BTEX) are the most monitored anthropogenic VOCs and are present mainly due to motor vehicles emissions. Additionally, biomass burning contributes to anthropogenic VOCs, especially high molecular weight VOCs, e.g. methanol and acetonitrile. The relative contributions of VOC species to ozone are determined through the level of the Ozone Formation Potential (OFP) of different species. Emissions of VOCs (e.g. very short-lived halogenated gases) in the tropics are capable of contributing to stratospheric ozone depletion. BTEX has been identified as the main types of VOCs that are associated with the cancer risk in urban areas in tropical regions. Finally, future studies related to VOCs in the tropics and their associated health risks are needed to address these concerns.

This study aims to evaluate the variation of PM2.5 components as well as to identify PM2.5 sources under non-hazy weather conditions in a tropical urban city, Petaling Jaya, Malaysia. The non-hazy weather conditions were characterized by copious rainfall throughout the year and ephemeral dry periods, with no significant haze events. The PM2.5 concentrations were recorded on the rooftop of an eight-floor building using a High Volume Sampler (HVS). The water-soluble ion (WSI), trace metal (TM) and organic and elemental carbon (OC-EC) content of PM2.5 was determined for source apportionment using the Positive Matrix Factorization (PMF) model. Daily PM2.5 concentrations were in the range 9.80–59.9 μgm−3. Dry weather conditions, rainfall and atmospheric stability in different seasons influenced the daily PM2.5 variations. The maximum PM2.5 concentration (33.1 μgm−3) was measured during the inter monsoon (INT I) season. The major constituents of PM2.5 were OC (6.80 μgm−3, 24.4%), EC (0.700 μgm−3, 2.5%) and inorganic matter (IM) (6.6 μgm−3, 23.7%). The PMF identified eight factor profiles of PM2.5 sources and the major source contributors were secondary inorganic aerosol (SIA), traffic and oil combustion (28.5%). We note that source characteristics of PM2.5 were significantly modulated by seasonal factors during non-hazy weather conditions.

The aim of the present study was to investigate the potential sources of heavy metals in fine air particles (PM

Benzene, toluene, ethylbenzene and xylenes (BTEX) are well known hazardous volatile organic compounds (VOCs) due to their human health risks and photochemical effects. The main objective of this study was to estimate BTEX levels and evaluate interspecies ratios and ozone formation potentials (OFP) in the ambient air of urban Kuala Lumpur (KL) based on a passive sampling method with a Tenax® GR adsorbent tube. Analysis of BTEX was performed using a thermal desorption (TD)-gas chromatography mass spectrometer (GCMS). OFP was calculated based on the Maximum Incremental Reactivity (MIR). Results from this study showed that the average total BTEX during the sampling period was 66.06 ± 2.39 μg/m3. Toluene (27.70 ± 0.97 μg/m3) was the highest, followed by m,p-xylene (13.87 ± 0.36 μg/m3), o-xylene (11.49 ± 0.39 μg/m3), ethylbenzene (8.46 ± 0.34 μg/m3) and benzene (3.86 ± 0.31 μg/m3). The ratio of toluene to benzene (T:B) is > 7, suggesting that VOCs in the Kuala Lumpur urban environment are influenced by vehicle emissions and other anthropogenic sources. The average of ozone formation potential (OFP) value from BTEX was 278.42 ± 74.64 μg/m3 with toluene and xylenes being the major contributors to OFP. This study also indicated that the average of benzene concentration in KL was slightly lower than the European Union (EU)-recommended health limit value for benzene of 5 μg/m3 annual exposure.

It is important to have good indoor air quality, especially in indoor office environments, in order to enhance productivity and maintain good work performance. This study investigated the effects of indoor office activities on particulate matter of less than 2.5 μm (PM

Level of benzene, toluene, ethyl benzene, m,p-xylene and o-xylene (BTEXs) was measured in several indoor and outdoor air samples. Five indoor air samples were from motor vehicle workshops and three samples were from gasoline filling stations and the rest were ambient air samples. They were collected using a 1L Tedlar® bag. BTEX analysis was performed with Thermal Desorption (TD) - Gas Chromatography Mass Spectrometer (GCMS). The concentration of ?BTEXs in indoor (ID1 to ID5) were 864.29, 115.32, 655.79, 72.99, 96.05 μg/m3 respectively. ?BTEXs in outdoor (OD1 to OD6) samples were, 367.45, 85.12, 50.29, 159.94, 46.02, 68.57 μg/m3 respectively. Calculated LADD value in indoor and outdoor air samples ranged in the scale of 0.27–3.42 and 0.16–1.88 μg/kg/d respectively. Concentrations of all indoor and outdoor samples surpassed the cancer risk (CR) limit for benzene but were below HQ (

The aim of the present study was to investigate the potential sources of heavy metals in fine air particles (PM2.5) and benzene, toluene, ethylbenzene, and isomeric xylenes (BTEX) in gas phase indoor air. PM2.5 samples were collected using a low volume sampler. BTEX samples were collected using passive sampling onto sorbent tubes and analyzed using gas chromatography-mass spectrometry (GC-MS). For the lower and upper floors of the evaluated building, the concentrations of PM2.5 were 96.4 ± 2.70 μg/m3 and 80.2 ± 3.11 μg/m3, respectively. The compositions of heavy metals in PM2.5 were predominated by iron (Fe), zinc (Zn), and aluminum (Al) with concentration of 500 ± 50.07 ng/m3, 466 ± 77.38 ng/m3, and 422 ± 147.38 ng/m3. A principal component analysis (PCA) showed that the main sources of BTEX were originated from vehicle emissions and exacerbate because of temperature variations. Hazard quotient results for BTEX showed that the compounds were below acceptable limits and thus did not possess potential carcinogenic risks. However, a measured output of lifetime cancer probability revealed that benzene and ethylbenzene posed definite carcinogenic risks. Pollutants that originated from heavy traffic next to the sampling site contributed to the indoor pollution.

It is important to have good indoor air quality, especially in indoor office environments, in order to enhance productivity and maintain good work performance. This study investigated the effects of indoor office activities on particulate matter of less than 2.5 μm (PM2.5) and ozone (O3) concentrations, assessing their potential impact on human health. Measurements of indoor PM2.5 and O3 concentrations were taken every 24 h during the working days in five office environments located in a semi-urban area. As a comparison, the outdoor concentrations were derived from the nearest Continuous Air Quality Monitoring Station. The results showed that the average 24 h of indoor and outdoor PM2.5 concentrations were 3.24 ± 0.82 μg m−3 and 17.4 ± 3.58 μg m−3 respectively, while for O3 they were 4.75 ± 4.52 ppb and 21.5 ± 5.22 ppb respectively. During working hours, the range of PM2.5 concentrations were 1.00 μg m−3 to 6.10 μg m−3 while for O3 they were 0.10 ppb to 38.0 ppb. The indoor to outdoor ratio (I/O) for PM2.5 and O3 was

Arcing fault is an overvoltage that usually occurs in the power system network, and it is necessary to monitor this phenomenon in electrical equipment. This paper presents the Rogowski coil (RC) as an arcing fault sensor. Finite element method (FEM) software used for analysing the RC magnetic flux density with two types of RC with the different turns and size demonstrated. The sizing of RC based on the 240 mm2 cross-link polyethene (XLPE) 11 kV underground cable. The prototypes of the RC sensors were designed using Solidworks software and three-dimensional (3D) printer for fabrication purposes. The main objective of the experiment is to investigate the RC effect with high magnetic flux density by implementing in real measurement. An experimental setup for real arcing fault with various voltages (up to 15 kV) was conducted to verify the RC performance, such as sensitivity and bandwidth range. The result has shown that the bandwidth of RC 1 is higher than RC 2 in all measurement by 22.6%.

Conventional air quality monitoring systems, such as gas analysers, are commonly used in many developed and developing countries to monitor air quality. However, these techniques have high costs associated with both installation and maintenance. One possible solution to complement these techniques is the application of low-cost air quality sensors (LAQSs), which have the potential to give higher spatial and temporal data of gas pollutants with high precision and accuracy. In this paper, we present DiracSense, a custom-made LAQS that monitors the gas pollutants ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO). The aim of this study is to investigate its performance based on laboratory calibration and field experiments. Several model calibrations were developed to improve the accuracy and performance of the LAQS. Laboratory calibrations were carried out to determine the zero offset and sensitivities of each sensor. The results showed that the sensor performed with a highly linear correlation with the reference instrument with a response-time range from 0.5 to 1.7 min. The performance of several calibration models including a calibrated simple equation and supervised learning algorithms (adaptive neuro-fuzzy inference system or ANFIS and the multilayer feed-forward perceptron or MLP) were compared. The field calibration focused on O3 measurements due to the lack of a reference instrument for CO and NO2. Combinations of inputs were evaluated during the development of the supervised learning algorithm. The validation results demonstrated that the ANFIS model with four inputs (WE OX, AE OX, T, and NO2) had the lowest error in terms of statistical performance and the highest correlation coefficients with respect to the reference instrument (0.8 &lt, r &lt, 0.95). These results suggest that the ANFIS model is promising as a calibration tool since it has the capability to improve the accuracy and performance of the low-cost electrochemical sensor.

This study aims to determine the composition of BTEX (benzene, toluene, ethylbenzene and xylene) and assess the risk to health at different sites in Malaysia. Continuous monitoring of BTEX in Kuala Lumpur City Centre, Kuala Terengganu, Kota Kinabalu and Fraser Hill were conducted using Online Gas Chromatograph. For comparison, BTEX at selected hotspot locations were determined by active sampling method using sorbent tubes and Thermal Desorption Gas Chromatography Mass Spectrometry. The hazard quotient (HQ) for non-carcinogenic and the life-time cancer risk (LTCR) of BTEX were calculated using the United States Environmental Protection Agency (USEPA) health risk assessment (HRA) methods. The results showed that the highest total BTEX concentrations using continuous monitoring were recorded in the Kuala Lumpur City Centre (49.56 ± 23.71 μg/m3). Toluene was the most dominant among the BTEX compounds. The average concentrations of benzene ranged from 0.69 ± 0.45 μg/m3 to 6.20 ± 3.51 μg/m3. Measurements using active sampling showed that BTEX concentrations dominated at the roadside (193.11 ± 114.57 μg/m3) in comparison to petrol station (73.08 ± 30.41 μg/m3), petrochemical industry (32.10 ± 13.13 μg/m3) and airport (25.30 ± 6.17 μg/m3). Strong correlations among BTEX compounds (p 0.7) at Kuala Lumpur City Centre showed that BTEX compounds originated from similar sources. The values of HQ at all stations were

The measurement of anthropogenic and biogenic volatile organic compounds (VOCs) in urban air is important because of their toxic effects and because they can produce secondary air pollutants (e.g. ozone, particulate matter). Benzene, toluene, ethylbenzene and xylenes (BTEX), representing anthropogenic VOCs (AVOCs), and isoprene, a biogenic VOC (BVOC), were monitored at an urban site in Kuala Lumpur (KL). Active sampling was conducted using sorbent tubes packed with Tenax®TA/1 TD for 5 days (daytime). Analysis of VOCs was performed using Thermal Desorption-Gas Chromatography Mass Spectrometry (TD-GCMS). Average daytime concentrations of VOCs were 9.42 ± 6.15 µg/m3 for benzene, 35.04 ± 12.60 µg/m3 for toluene, 11.20 ± 4.17 µg/m3 for ethylbenzene, 19.19 ± 10.76 µg/m3 for m,p-xylene, 18.40 ± 8.56 µg/m3 for o-xylene, and 6.70 ± 1.57 µg/m3 for isoprene. Weekday BTEX levels were found to be higher, especially during the morning rush hour, demonstrating the impact of traffic emissions in KL. BVOCs (isoprene) in urban KL was also higher than the reported isoprene level in Malaysian forest areas but lower than palm plantation areas. Both AVOCs and BVOCs significantly contributed to (218.6 - 733.8 µg/m3) ozone formation in the KL atmosphere.

Volatile organic compounds (VOCs) play an important role in the generation of ground level ozone and secondary organic aerosol. Most tropical countries such as Malaysia, Singapore, Indonesia, Brunei experience high ozone pollution. Beside ozone, oxides of nitrogen (NOx) from vehicular emissions also play an important role in photochemical pollution. NOx, particularly nitric oxide (NO), helps to ‘clean up’ ozone concentrations close to traffic in the ambient air of urban areas. Thus, knowledge of the chemistry of ozone-VOCs-NOx and finding the sources of VOCs are crucial to proceed with an appropriate mitigation strategy. Thus, the detection of ozone precursors and related VOCs is thoroughly discussed. This review finds that the inertness, hydrophobicity, and the effect of the artefact materials are very significant factors to be explored in the selection of the sorbent materials. In the SEA region, relative humidity is relatively high and exceeds 90% during the northeast monsoon. Thus, the hydrophobic properties of the sampling material need careful consideration. Further to the effect of relative humidity (RH), the artefact effect of the material itself is a challenge to be optimized and multi-sorbent material in a single tube could be a viable choice to minimize the effect of the unwanted signal in the spectrum.