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

Abstract This study aims to evaluate the air quality on Langkawi Island, a famous tourist destination in Malaysia, using 13 years of data (1999–2011) recorded by the Malaysian Department of Environment. Variations of seven air pollutants (O 3 , CO, NO, NO 2 , NO x , SO 2 and PM 10 ) and three meteorological factors (temperature, humidity and wind speed) were analysed. Statistical methods used to analyse the data included principal component regression (PCR) and sensitivity analysis. The results showed PM 10 was the dominant air pollutant in Langkawi and values ranged between 5.0 μg m −3 and 183.2 μg m −3 . The patterns of monthly values showed that the concentrations of measured air pollutants on Langkawi were higher during the south-west monsoon (June–September) due to seasonal biomass burning activities. High CO/NO x ratio values (between 28.3 and 43.6), low SO 2 /NO x ratio values (between 0.04 and 0.12) and NO/NO 2 ratio values exceeding 2.2 indicate the source of air pollutants in this area was motor vehicles. PCR analysis grouped the seven variables into two factor components: the F1 component consisted of SO 2 , NO and NO x and the F2 component consisted of PM 10 . The F1 component (R 2 = 0.931) indicated a stronger standardized coefficient value for meteorological variables compared to the F2 component (R 2 = 0.059). The meteorological variables were statistically significant ( p