Concentration of Major Air Pollutants during the Movement Control Order due to the COVID-19 Pandemic in Malaysia

Mohd Talib Latif,Kasturi Dewi Kaniiah,Murnira Othman,Doreena Dominick,Anis Asma Ahmad Mohtar,Nor Syamimi Sufiera Limi Hawar,Zaman, Nurul Amalin Fatihah Ka,Dimitrios G. Kaskaoutis 한국대기환경학회 2021 한국대기환경학회 학술대회논문집 Vol.2021 No.10

The spread of virus-related illnesses due to COVID-19 has been associated with the presence of the virus in water droplets released from infected individuals through processes such as coughing, sneezing and taking. Studies also indicated the potential for airborne transmission of COVID-19 especially within indoor environment. The level of air pollutants such particulate matter with aerodynamic diameter below than 2.5 micrometres (PM2.5) showed a significant relationship with the COVID-19 cases in many countries. On the other side, the lockdown due to COVID-19 pandemic has led to a notable decrease in atmospheric pollutants. Measurement of aerosols using satellite image in Southeast Asia shows a significant reduction of aerosols optical depth (AOD) during lockdown due to COVID-19 pandemic. In Malaysia based on ground level measurement, the concentration of PM10, PM2.5, NO₂, SO₂, and CO concentrations have been decreased by 26-31%, 23-32%, 63-64%, 9-20%, and 25-31%, respectively during the lockdown phase, compared to the same periods in 2018 and 2019. Surface ozone (O3) especially in urban area is the only gas that shows an overall increasing trend during the lockdown. Further investigation using diurnal patterns showed that NO₂ and CO were both reduced significantly during the rush hours, indicating how a reduction in motor vehicles on the roads influences the levels of these pollutants.

Making Sense of Sensor: An Update from Low-cost Air Quality Sensor for Air Quality Monitoring in Malaysia

Mohd Shahrul Mohd Nadzir,Sawal Hamid Md Ali,Mohd Talib Latif,Soo Wei Khor,Haris Hafizal Abd Hamid,Utbah Rabuan,Zaki Khaslan 한국대기환경학회 2021 한국대기환경학회 학술대회논문집 Vol.2021 No.10

Clean air is one of the most fundamental principles of life quality and well-being. Outdoor and indoor air pollutions both can contributes to human health problems. Conventionally, the methodologies adapted to measure indoor air pollutants are based on: (i) passive samplers, which require long sampling periods and/or (ii) continuous sampling, which generally are bulky and expensive, generating noise and vibration, preventing its deployment in many places at the same time, leading to a limited spatiotemporal coverage. In recent years, low-cost air pollution technologies have gained increasing interest and, consequently, have been studied widely by the scientific community for air pollutions monitoring. Thus, it is important that these new sensing technologies provide reliable data, with good precision and accuracy. Electrochemical (EC) sensors from AiRBOXSense were constructed to measure CO, NO₂, and O₃. Results showed that the sensors behaved highly linearly in laboratory experiments and had response times of around 0.5-1.6 min. In this study, a simple equation was used to translate the signal to mixing ratio and was calibrated by adding a correction in order to achieve the minimum difference against the gas standard. We found that with the added corrections such as the new sensitivity and offset to the quation with most of the pollutants were r² = 0.8 (p ˂ 0.01), the difference values between mixing ratio of EC sensor and gas standard became decreased. Furthermore, this equation is deployed together with the other calibration model which constructed using the machine learning to translate signal to mixing ratios in the field experiment. Nevertheless, it should be noted that the representatives of measurements in this result only showed during the conditions of this campaign. Thus, the use of low-cost sensing technology to monitor indoor air pollutions is encouraged, but not waiving the relevance of high quality instruments (mainly reference instruments) as reference.

Studies of Atmospheric PM2.5 and its Inorganic Water Soluble Ions and Trace Elements around Southeast Asia: a Review

Nadhira Dahari,Khalida Muda,Mohd Talib Latif,Norelyza Hussein 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.2

Air pollution is a worldwide issue that is mainly caused from excessive inhalation of hazardous PM2.5 pollutant that is emitted into the air. The objective of this study is to assess the fundamental knowledge revolving PM2.5 (particles aerodynamic diameter of lower than or equal to 2.5 μm) and its inorganic composition in ambient air of urban areas, mainly in Malaysia in comparison to other Southeast Asia countries. This research also investigates the theory of particle number concentration (PNC) with PM2.5, also the health effects and origins of the emissions. The factors affecting the PM2.5 mass include the local emission, El Nino phenomenon, land, meteorological effects, monsoons, rainfall events, sea breeze, transboundary pollution and seasonal changes. 24 h mean PM2.5 mass concentration for metropolitan regions in the SEA is in the range of 11 μgm−3 and 72.3 μgm−3, while between 5.30 μgm−3 and 55.89 μgm−3 for semi-urban zones. For rural area, the 24 h mean PM2.5 value is about 30 μgm−3. The findings indicate that metals inPM2.5 emission are frequently Pb, Se, Zn, Cd, As, Bi, Ba, Cu, Rb, V, Ni, Fe, Ca, Mn, Cr, Al, Si and K, where Zn has the uppermost range of 133.50 to 419.30 ngm−3 while the major water-soluble ions exist are NH4 +, K+, Ca2+, Na+, inwhichNa+, NH4 + and Cl- are present in aged sea salt and mixed industrial, Ca2+ and Mg2+ present in mineral dust, NH4 +, K+ and SO4 2− present in mixture of SIA and biomass burning. There is a high correlation between the particle mass concentration and PNC level, especially the ones in accumulation mode (PNC0.1–1.0) which are mostly originated from the emission of heavy traffic streets.

Air Quality Modelling and Sustainable Urban Traffic Management Strategies for Kuala Lumpur

Azliyana Azhari,Kadaruddin Aiyub,Mohd Talib Latif 한국대기환경학회 2021 한국대기환경학회 학술대회논문집 Vol.2021 No.10

This study predicts concentration and dispersion pattern of primary pollutants in Kuala Lumpur city centre. The forecast was carried out under different traffic scenarios; business as usual (BAU) and 30% traffic reduction to see the impact of traffic reduction for a sustainable city management. The Danish OML-Highway model was utilized to calculate hourly time series of particulate matter concentration and distribution caused by traffic emission under different scenario. The average concentration of PM2.5 are 37.6±24.3 μg/m³ and 35.3±23.9 μg/m³ for BAU and 30% traffic reduction scenario respectively, while average concentration of PM10 are 54.5±27.8 μg/m³ and 50.8±26.4 μg/m³ for BAU and 30% traffic reduction scenario respectively. The spatial concentration distribution of annual mean for all primary pollutants in Kuala Lumpur City Centre clearly indicated that the concentration of particulate matter decreases with reduction of traffic volume in the city. The average mean concetration for CO during the BAU runs are ranging at 861-1439 μg/m³ compared to during 30% traffic reduction run at 834-1294 μg/m³. The average mean concentration for NO₂ during the BAU runs are ranging at 31.9-95.8 μg/m³ compared to during 30% traffic reduction run at 28.6-83.9 μg/m³. Average mean concentration for PM2.5 and PM10 during BAU runs are ranging at 30.4-43.7 μg/m³ and 41.4-65.9 μg/m³ respectively compared to during 30% traffic reduction run at 29.9-40.3 μg/m³ and 40.5-59.5 μg/m³ respectively. The average mean concentration for O₃ during the BAU runs are ranging at 3.81-28.6 μg/m³ compared to during 30% traffic reduction run at 5.05-30.7 μg/m³. This research demonstrates that traffic emission in urban area originates from vehicle emission and reduction of traffic volume in the city contributes to reduce the concentration of particulate matter pollution that is harmful to the environment and human health.