Pencemaran habuk di Lembah Klang melalui analisis statistik boxplot (Gauging dust pollution in Malaysia’s Klang Valley using statistical analysis of boxplot)

Abstract

Salah satu punca masalah kemerosotan kualiti udara bandar di Lembah Klang berlaku akibat daripada peningkatan bahan pencemar udara partikel zarah terampai berdiameter kurang daripada 10 mikron (PM10) daripada kenderaan bermotor selain faktor perbandaran yang pesat. Kajian ini bertujuan untuk mengkaji tren kepekatan purata bulanan PM10 di lima stesen kualiti udara di Lembah Klang iaitu Klang, Petaling Jaya, Kajang, Shah Alam dan Cheras dari 2000 hingga 2009 dengan menggunakan kaedah statistik boxplot. Hasil kajian mendapati bahawa tren kepekatan purata bulanan PM10 adalah lebih tinggi daripada nilai kesetaraan Recommended Malaysian Air Quality Guidelines (RMAQG) iaitu 103.5 μg/m3 untuk tempoh sebulan bagi beberapa stesen kajian. Nilai kepekatan PM10 bulanan yang tertinggi direkodkan adalah pada Ogos 2005 sebanyak 590 μg/m3 di stesen Klang, 482 μg/m3 (Petaling Jaya), 371 μg/m3 (Kajang) serta 587 μg/m3 (Shah Alam) dan Cheras sebanyak 465 μg/m3 sewaktu peristiwa jerebu pada ketika itu. Selain nilai maksimum, analisis boxplot turut mewakili nilai Q2 (kuartil 2) iaitu nilai median atau penengah data, IQR (julat antara kuartil) iaitu angka penengah antara nilai yang paling kecil dan median serta Q3 (kuartil 3) merupakan nilai tengah antara median dan nilai tertinggi sesuatu set data. Stesen Klang mencatatkan nilai Q3, IQR dan Q2 tertinggi pada tahun 2005 masing-masing sebanyak 342 μg/m3, 75 μg/m3 dan 277 μg/m3 pada bulan Ogos berbanding stesen lain. Episod jerebu yang serius berlaku di Semenanjung Malaysia pada waktu tersebut berasal daripada pembakaran biojisim di Sumatera, Indonesia dan faktor kedudukan Klang yang paling hampir dengan Sumatera adalah punca utama kepada peningkatan kepekatan PM10 yang tinggi di stesen tersebut.

Katakunci: analisis statistik boxplot, kenderaan bermotor, kualiti udara bandar, Lembah Klang, pencemaran jerebu, PM10

One of the sources of urban air quality deterioration in the Klang Valley was increased emissions of suspended particulates matter sized less than 10 micrometers (PM10) from motor vehicles. This study investigated the trend of monthly average concentrations of PM10 at Klang, Petaling Jaya, Kajang, Shah Alam and Cheras air quality stations from year 2000 to year 2009 using the boxplot statistical analysis. It was found that the monthly average concentrations of PM10 from 2000 to 2006 at all stations exceeded the monthly average equivalent of the Recommended Malaysian Air Quality Guidelines (RMAQG) of 103.5 μg/m3 for a period of one month at several air quality stations. The highest monthly concentration of PM10 was recorded at Klang (590 μg/m3), Petaling Jaya (482 μg/m3), Kajang (371 μg/m3), Shah Alam (587 μg/m3) and Cheras (465 μg/m3) in Ogos 2005. Besides the maximum concentration, boxplot also analysed the Q2 (quartile 2) and the third quartile (Q3) scores. The Klang air quality station recorded the highest monthly values of Q3, Q2 and IQR in August 2005 at 342 μg/m3, 75 μg/m3 and 277 μg/m3, respectively. This situation occurred as an impact of the major haze episode that originated from the biomass burning activities in Sumatra, Indonesia. The location of the Klang air quality station nearest to Sumatra was one of the reasons that the maximum PM10 concentrations were recorded there.

Keywords: boxplot statistical analysis, dust pollution, Klang Valley, motor vehicles, PM10, urban air quality