| dc.description.abstract | Petroleum refueling emissions have increased relative to vehicular related emissions
corresponding to the growth in motor vehicles. Although exposure to VOCs at service stations is
hazardous to the workers and the environment, policy on its assessment, monitoring and
regulation in Kenya is yet to be implemented by the government. Consequently, this study was
conducted to identify and quantify VOCs, to which service station attendants are exposed, in
selectedservice stations in the city of Nairobi.
Air samples were obtained using passive samplers attached to the clothing of service attendants
performing routine daily activities for an 8 hour period. Soil was collected from a central point,
sieved,dried, packed in a box and placed strategically at the service stations and sampled after 8
hours. Effluent from service station was collected into glass amber. All samples were sealed,
transported and stored at 4°C before extraction.
The samples were analyzed with Agilent 6890N gas chromatograph equipped with flame
ionization detector (GC/FID) and analytical fused silica J&W DB WAX (polar - polyethylene
glycol) colunm whose dimensions were 0.25 urn film thickness, 0.25 mm 1.0., approximately 30
m in length. White spot nitrogen was used as both the carrier and makeup gas, while hydrogen
was used as fuel and compressed air as the flame gas.
A total of 40 air samples.-ou soil samples and 45 water samples were routinely monitored for
BTEX, chloroform, hexane, isooctane, naphthalene and 2-propanol every other week over a
period of three months. The recovery of the analyte were between 89.975% and 99.313% while
detection limits ranged from 0.019 ppb (0.005 ug/rrr' for toluene) to 0.763 ppb (0.156 ug/m' for
chloroform). Benzene, toluene, ethyl benzene and isomers of xylene, which are collectively
referred to as BTEX, since their similar chemical structures, fate and transport properties,
constituted the major VOCs detected in the air samples. The most abundant compounds in
personal air at the service station in order of decreasing concentration (units: ug/rrr') were: ethyl
benzene (52.847), benzene (40.64), chloroform (12.72), (2, 2, 4-trimethylpentane (5.57), hexane
(4.645), m,o,p-xylene (3.44), naphthalene (3.2) and toluene (3.06). Benzene time-weighted
average (TWA) to service ·station attendants ranged from 0.92 to 182.13 ug/m' and were below
WHOguidelines (319.43 ug/rrr').
Benzene, hexane, chloroform, and 2, 2, 4-trimethylpentane were mainly found in the soil
samples. The most abundant compounds in soil at the service station in order of decreasing
concentration (ug/Kg) were: Hexane (36.20), Ethyl benzene (31.86) and Benzene (23.88).
Benzene was the most abundant of the VOCs in water samples, with a mean of 2.84 mg/L
followed by chloroform (0.42 mg/L), n-hexane (0.27 mg/L) and isooctane (0.20 mg/L). Mean
chloroform levels detected in air, soil and water samples were 16.66 ug/m ', 133.12 ug/Kg and
...
7.67mg/L respectively. The concentrations of the target VOCs were comparable in all the
servicestations suggesting minimal external interference. There is need to monitor, regulate and
furtherdetermine occupational health effects by analyzing the levels in urine, blood and skin of
theservice attendants. | en |
