Determination of the levels of heavy metals in Suspended particulate matter (SPM) in Kibera (Nairobi)

Abstract

High population density, industrialization and increased vehicle use have led to severe deterioration of air quality in most urban centres. The most obvious air pollutant is the increased load of suspended particulate matter, which is known to have serious implication on human health. Health effects are mostly associated with particles in the size range of about 10 micrometres and below. It was therefore the aim of this study to determine the levels of suspended particulate matter in Kibera, the variation of the particulate matter levels with weather parameters such as rainfall, humidity and temperature, their heavy metal content and to correlate these levels with incidences of acute respiratory infections (ARl) of children under five years of age. Dustfall in a typical office working environment was also monitored by way of exposing pre-weighed coarse filters in the office and laboratory environment. In this study, data on suspended particulate matter (SPM) collected over a one year period in Kibera, a suburban area of Nairobi is presented and discussed. The SPMwas monitored as PMIOusing the "Gent" Stacked Filter Unit (SFU) at heights of two (2) and four (4) metres above the ground level. The suspended particulate matter (SPM) was analysed by gravimetric, atomic absorption spectrometry (AAS) and energy dispersive X-ray fluorescence (EDXRF) techniques. The data analysis included calculation of interelement correlations (pearson-product moment) and enrichment factors. For the acute respiratory infections (ARI) incidences, a questionaire administered It) the mother elicited information on the symptoms. A total of 146 children were followed throughout the year. The ARI incidences ranged from (29.9-59.6%). The mean PMJOvalues varied from (77.6-159.1~lg/m3) for samples collected at a height of two (2) metres and (60.9-138~lg/m3) at four (4) metres above the ground. These values are higher than previous data (30-80J.!g/m3) reported for a sub-urban site in Nairobi.