Assessment Of Levels Of Urban Air Pollutants And Trace Elements In Roadside Soils; A Case Study In Eastleigh Area, Nairobi

Abstract

In this study, the assessment of five most common air pollutants from vehicular emissions were done along Juja road in Eastleigh area, Nairobi. Sampling was done for soil samples, particulate matter (PMIO), sulfur dioxide (S02), carbon monoxide (CO), nitric oxide (NO) and nitrogei dioxide (N02)' Sampling for PMIO an,' soil samples was done during dry and rainy season, while sampling for S02, CO, NO and N02 was done during the dry season. Rainy season sampling was done during the month of April 2005, while sampling for dry season was done from November 2005 to January 2006. Gases and PMIOsampling was 'done in 3 places along Juja road (described as Area 1,2 and 3). Area 1 was at St. Theresa Catholic Church, which is near Eastleigh Avenue 1 and Juja road junction. Sampling Area 2 was at Radiant hospital near Pangani roundabout, while Area 3 was near Hururna Chief's office, near Mathare North road and Juja road junction. Sampling for S02, N02, NO and CO pollutants was done using Z-1300XP, Z- 1400XP, Z-700XP and Z-500XP monitors respectively, and "Gent" stack filter unit (SFU) was used for PMlO sampling. In area 1, the sampling was done for 5 days while in area 2 and 3 it was done for 4 days. The measurements were taken for 8 hours (from 9.30 am to 5.30 pm). This was repeated for PMIOduring rainy season and a total of 55 samples were collected and analyzed using EDXRF for elemental content. Vehicle tallying was done in area 1 and 3, for 8 hours on Fridays while sampling for the gases. Soil samples were col.: .cted at an interval of approximately 250 meters along Juja road. And at point 4 other sarples were collected in consecutive places (about 20 meters apart) away from the road. Top surface soil sample weighing 0.5 to 1 kg (0-2 ern), was scooped out within 1 meter from the road kerb. A total of 50 soil samples were collected in both dry and rainy season. The soil samples were analyzed in triplicate, and the mean obtained. Association between air pollutants levels and the vehicle density was assessed by performing a simple correlation analysis. ANOV A was used to indicate any statistical differences in concentration levels for different pollutants at P=<0.05.