Determination of concentration of total suspended particulate matter and some gaseous air pollutants in Athi river urban area, in Kenya

Abstract

A study for the assessment of air quality with respect to total suspended particulate matter, heavy metals (Zn, Cd, Pb, Cu, Mn, Fe) analysis together with S.02 H2S, and NH3 gases emitted in Athi-River town was carried out. Concentrations of the daily samples collected at various sites during the whole sampling period were determined using gravimetric and Atomic / Molecular spectrophotometric instrumental methods: The data so obtained were analysed using the cumulative frequency distribution method on log - probability graph paper. The use of log - probability cumulative frequency distribution curves in determining the number of times when hourly total suspended particulate matter or half - hourly sulphur dioxide, hydrogen sulphide and ammonia concentrations equalled or exceeded or were in the range of indicated levels at selected sites, was discussed. The correlation between diurnal concentration cycles and meteorological variables (temperature and relative humidity) was presented. Variation of the pollutants concentrations with time showed diurnal high values for hydrogen sulphide and.ammonia at industrial area during 1200 - 1400 hours, and 1000 - 1130hours & 1400 - 1700hours respectively. This was partly attributed to increased microbial activity on waste waters from Barbar, Bawazir and Fishmeal factories which resulted into increased hydrogen sulphide and ammonia generation during midday or close to midday temperature. Industrial emissions as a result of thermal breakdown of animal and plant protein products at fish meal and Athi Thread Factories respectively were also implicated as contributory sources to increased ammonia pollutant levels. High concentration levels for total suspended particulate matter and sulphur dioxide pollutants at urban commercial area during 1000-1200hours and 1300 - 1700hours were associated with increased traffic volume during morning, midday and evening hours. This was in addition to long-range transport of the pollutants from Industrial heating processes and power generation at the beginning of industrial operations. Diurnal concentration values were also noted to be high at low humidity and high temperatures.