Comparative Analysis of PM10 and PM2.5 Before, During, and After the COVID-19 Pandemic in Shah Alam, Malaysia

Fairus Muhammad Darus; Nurul Latiffah Abd Rani; Nurul Nisa’ Khairol Azmi

Authors

Fairus Muhammad Darus School of Chemistry & Environment, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia
Nurul Latiffah Abd Rani School of Chemistry & Environment, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia
Nurul Nisa’ Khairol Azmi Centre of Mathematical Sciences, Faculty of Computer and Mathematical Sciences, Universiti Teknologi MARA, Seremban Campus, 70300 Seremban, Negeri Sembilan, Malaysia

Keywords:

Air Pollution Trends, PM10, PM2.5, Shah Alam, COVID-19

Abstract

Particulate matter (PM₁₀ and PM_2.5) is a major environmental and public health concern due to its ability to penetrate the human respiratory system and elevate risks of respiratory and cardiovascular diseases. This study examines the impact of COVID-19 restrictions on PM₁₀ and PM_2.5concentrations in Shah Alam, Malaysia, from 2018 to 2023, covering three phases: pre-COVID (2018–2019), COVID (2020–2021), and post-COVID (2022–2023). Daily 24-hour mean data from the Department of Environment were analysed using the Kruskal–Wallis test with Dunn’s post hoc comparisons. Results revealed significant differences across the three phases (p < 0.001). PM₁₀ and PM_2.5concentrations declined sharply during the COVID period by approximately 29% and 32.5%, respectively, compared to pre-COVID levels, with large effect sizes confirming substantial reductions. Post-COVID years showed modest rebounds but remained 23% (PM₁₀) and 25.5% (PM_2.5) lower than pre-pandemic baselines. These findings align with national and international evidence, underscoring the strong influence of anthropogenic activity on particulate matter levels. The results highlight the importance of integrating emission control policies with regional haze management to sustain long-term improvements in urban air quality.

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