Variation of major air pollutants in different seasonal conditions in an urban environment in Malaysia

Abstract

Urban air quality has been deteriorating over time. Pollutant distribution levels in the urban environment may be associated with anthropogenic sources and meteorological conditions. The aim of this study is to determine the variation in concentrations of major air pollutants: carbon monoxide (CO), ozone (O 3), nitrogen dioxide (NO 2), sulphur dioxide (SO 2) and particulate matter (PM 10), with corresponding seasonal variation in a Malaysian urban environment. Eleven years of data from four selected stations, namely Klang (S1), Petaling Jaya (S2), Shah Alam (S3) and Cheras (S4), were analysed for temporal trend variations (yearly and monthly). Statistical analysis using Openair, an R package open source software, has been conducted to assess pollutants in relation to meteorological conditions. Gas concentrations showed little variation between the study sites apart from NO 2 , which recorded its highest concentrations at an industrial site, between 23 and 40 ppb, and is associated with industrial and vehicle emissions. Pollutants that show seasonal variations and frequently exceed the Malaysia Ambient Air Quality Standard (MAAQS) and the National Ambient Air Quality Standard (NAAQS) are O 3 and PM 10 , predominantly related to the monsoon seasons. High levels of O 3 during the northeast monsoon (January-March) are associated with high levels of the precursors of O 3. The concentration of PM 10 associated with tropical biomass burning during southwest monsoon. Shipping emissions and power stations are main contributors for higher level of SO 2. This study shows regional and local factors contribute to the different type of air pollutant concentrations in urban environment.

The concentration of major air pollutants during the movement control order due to the COVID-19 pandemic in the Klang Valley, Malaysia

“…The same results were observed in other locations where the effect of lockdown was a reduction of NO 2 ( Baldasano, 2020 ; Cameletti, 2020 ; Kerimray et al, 2020 ; Lian et al, 2020 ; Pei et al, 2020 ) and CO ( Ghahremanloo et al, 2021 ; Kerimray et al, 2020 ). Other pollutants, such as PM and SO 2, are expected to originate from other sources such as soil dust, sea breezes, construction, coal-fired power plants and industrial activities, aside from the use of motor vehicles ( Azhari et al, 2018 ; Keywood et al, 2003 ; Mohtar et al, 2018 ; Sulong et al, 2017 ). Therefore, PM and SO 2 concentrations were not necessarily reduced by the lower numbers of motor vehicles during the MCO.…”

Ambient air quality of a less industrialized region of India (Kerala) during the COVID-19 lockdown

“…Although the LD 2020 showed a decrease of the concentration of the air pollutants in Kerala State, the reduction in the concentration (due to lockdown) cannot be determined without estimating the role of short-term fluctuations or the seasonal trends in the concentration of the air pollutants during the analysis period. The fluctuations can relate to meteorological, seasonal or even anthropogenic and cultural factors ( Chen et al, 2015 ; Cichowicz et al, 2017 ; Mohtar et al, 2018 ). Zangari et al (2020) observed hardly any significant changes in the concentration of PM 2.5 and NO 2 in New York City during the lockdown period compared to the same period in 2015-2019.…”

The long-term assessment of air quality on an island in Malaysia

“…High NO 2 concentration at night time divert the initial step of VOC oxidation by forming nitric acid, which prevent the formation of O 3 as well [87]. In addition, high traffic volume and industrial emissions may contribute to increasing NO 2 in the Langkawi Island [88]. These simultaneous measurements of NO, NO 2 , NO x and O 3 indicated that the fraction of primary and secondary NO 2 in the Langkawi Island varied depending on mixing and photochemical conditions [89].…”