Open AccessMeasurements and analysis of air quality in Islamabad, Pakistan
Author(s) -
Rasheed Anjum,
Aneja Viney P.,
Aiyyer Anantha,
Rafique Uzaira
Publication year - 2014
Publication title -
earth's future
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.641
H-Index - 39
ISSN - 2328-4277
DOI - 10.1002/2013ef000174
Subject(s) - ozone , particulates , environmental science , pollutant , air quality index , mass concentration (chemistry) , sulfur dioxide , atmospheric sciences , environmental chemistry , air pollutants , air pollution , chemistry , geography , meteorology , physics , inorganic chemistry , organic chemistry
Ambient air quality of Islamabad, Pakistan, reveals that annual average mass concentration of particulate matter ( PM 2 .5 ) (∼45 to ∼95 µg m −3 ) and nitric oxide ( NO ) (∼41 to ∼120 µg m −3 ) exceeds the Pakistan's National Environmental Quality Standards ( NEQS ). The annual ozone ( O 3 ) concentration is within the permissible limits; however, some of the hourly concentration exceeds the NEQS mostly during the summer months. Correlation studies suggest that carbon monoxide ( CO ) has a significant ( p ‐value ≤ 0.01) positive correlation with NO and NO y′ ; whereas, with O 3 , a significant ( p ‐value ≤ 0.01) negative correlation is observed. The regression analysis estimates the background CO concentration to be ∼300 to ∼600 ppbv in Islamabad. The higher ratio of CO / NO (∼10) suggests that mobile sources are the major contributor to NO concentration. On the other hand, the ratio analysis of sulfur dioxide ( SO 2 )/ NO for Islamabad (∼0.011) indicates that the point sources are contributing to SO 2 in the city. NO and SO 2 correlation indicates contribution of direct sulfur emission sources. Ratios of [ CO ] to [ NO ] and [ SO 2 ] to [ NO ], based on ambient air quality measurements, provide a test for emission inventories. The ratios of these pollutants in the available Islamabad emission inventories are consistent with ambient values for these pollutants. The correlation of PM 2 .5 and NO suggests that a fraction of secondary PM 2 .5 is produced by chemical conversion of NO into nitrates. The regional background O 3 concentration for Islamabad has been determined to be ∼31 ppbv. This study suggests that there is an increase in O 3 concentration with increases in photochemical conversion of NO to reservoir NO y′ species.