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VOCs have been one of the important limiting factors of O3 photochemical production in the urban tropical region. This study aims to determine the variation and composition of aromatic VOCs as well as their contribution to the O3 formation. The hourly data of benzene, toluene, ethylbenzene and xylenes (BTEX) and ozone (O3) were retrieved from January until December 2019 at three continuous air quality monitoring stations (S1, S2 and S3) operated by the Malaysian Department of Environment (DOE). Aromatic VOCs is detected by using an online gas chromatography analyser (GC 5000BTX). The annual average ΣBTEX concentrations ranged from 14.53 ± 12.43 μg m-3 to 25.04 ± 24.04 μg m-3 during the observation period, with toluene as the most dominant species with an average concentration of 10.65 ± 12.12 μg m-3. The O3 formation potential (OFP) was calculated and the results indicated that toluene is the highest contributor of O3-forming potential, followed by m, p-xylene, o-xylene, ethylbenzene and benzene with the value of 127.8 μg m-3 (40.90 %), 103.0 μg m-3 (32.97 %), 48.66 μg m-3 (15.58 %), 26.17 μg m-3 (8.38 %) and 6.74 μg m-3 (2.15 %), respectively. Since the study of VOCs in Malaysia is quite limited, a more comprehensive study is currently underway to integrate the research on variation of VOCs in ambient air and its impact on the environment and human health.

Sarawak Region of Malaysia is currently experiencing a high demand for capital needs such as transformation forest to plantations, economic development, and improving transportation systems. Those land cover changes will increase primary pollutant emissions and trigger surface O3 formation. Surface O3 is a secondary pollutant and a significant greenhouse gas contributing to climate change and declining air quality. In this study, variations in surface O3 concentrations at urban and suburban sites in Sarawak were explored using the Malaysian Department of Environment data spanning a two-year cycle (2018-2019). The primary aim of this study is to ascertain the variation of surface O3 concentrations reported at four monitoring stations in Sarawak, namely Kuching (SQ1) (Urban), Sibu (SQ2) (Suburban), Bintulu (SQ3) (Suburban), and Miri (SQ4) (Suburban). The study also analysed the relationship between O3 distribution and nitrogen oxides (NO and NO2). The findings showed that O3 concentrations observed in the region during the study period were lower than the maximum permissible value of 100 ppbv suggested by the Malaysian Ambient Air Quality Standard (2020). SQ4 (Miri) at suburban sites recorded the highest average surface O3 concentrations with an hourly average and daily maximum O3 concentration of 15.7 and 89.5 ppbv, respectively. Temperatures, UV exposure, and wind speed all impact the concentration of surface O3 in Sarawak. In all stations, concentrations of O3 were inversely linked with NO, NO2, and relative humidity (RH). This research will assist the relevant agency in forecast, monitor, and mitigate the level of O3 in the ambient environment, especially in the Sarawak Region.

Particulate matter (PM) emissions from vegetation and peat fires in Equatorial Asia cause poor regional air quality. Burning is greatest during drought years, resulting in strong inter-annual variability in emissions. We make the first consistent estimate of the emissions, air quality and public health impacts of Equatorial Asian fires during 2004–2015. The largest dry season (August—October) emissions occurred in 2015, with PM emissions estimated as 9.4 Tg, more than triple the average dry season emission (2.7 Tg). Fires in Sumatra and Kalimantan caused 94% of PM emissions from fires in Equatorial Asia. Peat combustion in Indonesian peatlands contributed 45% of PM emissions, with a greater contribution of 68% in 2015. We used the WRF-chem model to simulate dry season PM for the 6 biggest fire years during this period (2004, 2006, 2009, 2012, 2014, 2015). The model reproduces PM concentrations from a measurement network across Malaysia and Indonesia, suggesting our PM emissions are realistic. We estimate long-term exposure to PM resulted in 44 040 excess deaths in 2015, with more than 15 000 excess deaths annually in 2004, 2006, and 2009. Exposure to PM from dry season fires resulted in an estimated 131 700 excess deaths during 2004–2015. Our work highlights that Indonesian vegetation and peat fires frequently cause adverse impacts to public health across the region.

The excessive inhalation of pollutant particles with aerodynamic diameters less than 2.5 µm (PM2.5) results in risking the human respiratory health. The aim of this study is to investigate the possible pathways of long range and local tranportation for PM2.5 sources. The route patterns are analyzed by using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT 4.9) software during August 2017 to January 2018, covering three main monsoon seasons of Malaysia; southwest (SW), intermonsoon (IM) and northeast (NE) monsoon. This study represents the 72 h air mass backward trajectories in a mixed commercial-residential-industrial site of Skudai, Johor Bahru. The identified source origins are largely varied with different monsoon seasons and meteorological factors. The air-flow at different altitudes results in different effects, as the trajectory at height 500 m contributes to the greatest impact on the pollution level. The potential sources were generally from the Sumatera, Indonesia, during SW monsoon and China, during NE monsoon. The PM2.5 exceedance pattern in the Skudai area is also strongly influenced by the localized circulation, anthropogenic emission and dispersion characteristics. The increased levels of PM2.5 are predominantly contributed by the primary sources of vehicular emissions and industrial activities.

Urban workers are susceptible to traffic-related air pollution (TRAP) exposure that can increase the prevalence of respiratory health symptoms among them. PM2.5 was the main pollutants emitted from vehicle emission during fossil fuel combustion. This will influence TRAP level in an urban environment. This study was a cross-sectional comparative study that conducted among traffic policemen (n = 160) and office workers (n = 149) in Klang Valley. The respondents' information and respiratory health symptoms were gathered using a set of questionnaire that adapted from American Thoracic Society (ATS). The air samples for personal exposure and workplace exposure were collected during working hours. The average PM2.5 levels for traffic policemen was 87µg/m3 (personal) and 86µg/m3 (workplace). The average PM2.5 levels for office workers was 28µg/m3 (personal) and 26µg/m3 (workplace). The statistical results of PM2.5 levels between both groups are significant difference for personal exposure (z = −15.685, p < 0.001) and workplace exposure (z = −14.519, p

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.

Today, ozone has become one of the main air pollutants in Malaysia. The high ozone precursor concentrations have been encouraging the ozone production. The development of the Klang Valley, Malaysia has many types of physical activities such as urban commercial, industrial area, settlement area and others, which has increased the risk of atmospheric pollution. The purpose of this paper is to determine the spatial distribution between types of land use and ozone concentration that are occurred in the year 2014. The study areas for this paper include Shah Alam, Kajang, Petaling Jaya and Port Klang. Distribution of ozone concentration will be showed via spatial analysis tools in Geographic Information Systems (GIS) approached and the types of land use will be extracted using Remote Sensing technique. The result showed 97 ppb (parts-per-billion, 10-9) and 161 ppb recorded at Port Klang and Shah Alam respectively that are mainly represented by the settlement area. Therefore, the physical land use need to be monitor and controlled by the government in order to make sure the ozone production for daily per hour will not exceed the regulation allowed.