标题：Air quality assessment of carbon monoxide, nitrogen dioxide and sulfur dioxide levels in Blantyre, Malawi: A statistical approach to a stationary environmental monitoring station
期刊名称：African Journal of Environmental Science and Technology
电子版ISSN：1996-0786
出版年度：2014
卷号：8
期号：6
页码：330-343
DOI：10.5897/AJEST2014.1696
语种：English
出版社：Academic Journals
摘要：Air quality in urban areas is a cause of concern because of increased industrial activities that contribute to large quantities of emissions. The study assess levels and variations of carbon monoxide (CO), nitrogen dioxide (NO2) and sulfur dioxide (SO2) in Blantyre, Malawi using a stationary environmental monitoring station (EMS).Results show that CO level (2.47 ± 1.23 mg m-3) were below the Malawian limit value (10.31 mg m-3). Although, NO2(4.02 ± 2.47 mg m-3) and SO2(8.58 ± 2.88 mg m-3) were significantly higher than allowable Malawian Standards (0.52 and 0.23 mg m-3, respectively). Discernible variations in hourly, diurnal, monthly and seasonal CO, SO2 and NO2 were apparent. Independent t-test confirmed that day time values were higher than those at night (p < 0.05). Thus, variations in local weather affect the disparity in hourly and diurnal values. Analysis of variance (ANOVA) confirmed significant variations in monthly observations. Moreover, independent t-test showed that wet season CO (2.32 mg m-3), SO2 (5.10 mg m-3) and NO2(9.41 mg m-3) levels were higher than dry season values (CO = 2.32 mg m-3; SO2 = 3.42 mg m-3; NO2 = 8.13 mg m-3). A hierarchical cluster analysis (HCA) divided the 10 months into three groups based on distribution of CO, SO2 and NO2, air temperature, wind speed and wind direction. Furthermore, factor analysis (FA) showed that air temperature had significant contribution to variations in mean values of CO, SO2 and NO2 for the entire study period. The study shows a need for constant urban air quality monitoring in Blantyre and all urban areas in Malawi. It is recommended that the experimental site widen the scope of the study by utilizing the flexibility of the EMS.
关键词：Air pollutants; principal component analysis; developing countries; environmental monitoring station; Kaiser normalization
