Customer exposure to gasoline vapors during refueling at service stations.

Gasoline is a volatile complex mixture of hydrocarbon compounds that is easily vaporized during handling under normal conditions. Modern reformulated gasoline also contains oxygenates to enhance octane number and reduce ambient pollution. This study measured the difference in the exposure of customers to gasoline and oxygenate vapors during refueling in service stations with and without vapor recovery systems. Field measurements were carried out at two self-service stations. One was equipped with Stage I and the other with Stage II vapor recovery systems. At Stage I stations there is vapor recovery only during delivery from road tanker, and at Stage II stations additional vapor recovery during refueling. The exposure of 20 customers was measured at both stations by collecting air samples from their breathing zone into charcoal tubes during refueling with 95-octane reformulated gasoline. Each sample represented two consecutive refuelings. The samples were analyzed in the laboratory by gas chromatography using mass-selective detection for vapor components. The Raid vapor pressure of gasoline was 70 kPa and an oxygen content 2 wt%. Oxygenated gasoline contained 7 percent methyl tert-butyl ether (MtBE) and 5 percent methyl tert-amyl ether (MtAE). The geometric mean concentrations of hydrocarbons (C3-C11) in the customers' breathing zone was 85 mg/m3 (range 2.5-531 mg/m3) at the Stage I service station and 18 mg/m3 (range < 0.2-129 mg/m3) at the Stage II service station. The geometric mean of the exposure of customers to MtBE during refueling at the Stage I service station was 15.3 mg/m3 (range 1.8-74 mg/m3), and at the Stage II service station 3.4 mg/m3 (range 0.2-16 mg/m3). The differences in exposure were statistically significant (p < 0.05). The mean refueling times were 57 seconds (range 23-207) at the Stage I and 66 seconds (range 18-120) at the Stage II station. The measurements were done on consecutive days at the various service stations. The temperature ranged from 10 to 17 degrees C, and wind velocity was 2-4 m/s. The climatic conditions were very similar on the measurement days. Based on this study it was found that the Stage II vapor recovery system reduces gasoline emission considerably. The exposure level of customers at the Stage II station during refueling was circa 20-25 percent of the exposure at the Stage I service station when conditions were equal and no other confounding factors such as leaks or spills were present.

Comparison of tanker drivers' occupational exposures before and after the installation of a vapour recovery system.

The purpose of this study was to compare tanker drivers' occupational exposure level before and after the installation of vapour recovery facilities at 14 service stations. Road tanker drivers are exposed when handling volatile petrol liquid in bulk in the distribution chain. The drivers' exposure was studied during the unloading operation as the bulk petrol flowed into underground storage tanks, displacing vapours in the tank space and causing emission to the environment and the drivers' work area. The exposures were measured again when the dual point Stage I vapour recovery systems were installed for recycling vapours. Short-term measurements were carried out in the drivers' breathing zones by drawing polluted air through a charcoal tube during unloading. The samples were analysed in the laboratory by gas chromatography for C3-C11 aliphatic hydrocarbons, tert-butyl methyl ether (MTBE), tert-amyl methyl ether (MTAE), benzene, toluene and xylene. The road tanker loads delivered consisted of oxygenated and reformulated petrol (E95 and E98 brands), which contained on average 13% oxygenates. Before the installation of the vapour recovery system, the geometric mean (GM) concentration of aliphatic hydrocarbons was 65 mg m-3 (range 6-645 mg m-3) in the drivers' breathing zones. After the installation at the same service stations, the corresponding exposure level was 8.3 mg m-3 (range < 1-79 mg m-3). The GM of the MTBE concentrations was 8.6 mg m-3 (range 1-67 mg m-3) without vapour recovery and 1.5 mg m-3 (range < 0.1-10 mg m-3) with vapour recovery. The differences between the aliphatic hydrocarbons and the MTBE exposure levels during the unloading of the road tankers without and with vapour recovery were statistically significant (p < 0.05).

Exposure of gasoline road-tanker drivers to methyl tert-butyl ether and methyl tert-amyl ether.

Organic oxygenates, namely, methyl tert-butyl ether (MTBE) and methyl tert-amyl ether (MTAE), are added to gasoline to reduce carbon monoxide in exhausts and to enhance the octane number. The aim of this study was to investigate road-tanker drivers' exposure to oxygenate vapors during road-tanker loading and unloading as well as to evaluate the measurements of these ethers and their metabolites in the urine as a means of assessing the uptake of the ethers. A total of 11 drivers in different parts of Finland were trained to monitor their exposure with personal samplers, to report their working conditions, and to collect their whole-day urine samples. Charcoal tubes of the air samples were analyzed for MTBE, MTAE, benzene, toluene, and aliphatic hydrocarbons. For biological monitoring purposes the two main oxygenates, tertiary ethers MTBE and MTAE, as well as their main metabolites, tertiary alcohols tert-butanol (TBA) and tert-amyl alcohol (TAA), were determined in urine specimens. On average the drivers were exposed to vapors for short periods (21 +/- 14 min) three times during a work shift. The mean concentrations of MTBE and MTAE (mean +/- SD) were 8.1 +/- 8.4 and 0.3 +/- 0.4 mg/m3. The total MTBE uptake during the shift was calculated to be an average of 106 +/- 65 mumol. The mean concentrations of MTBE, TBA, MTAE and TAA detected in the first urine after the work shift were 113 +/- 76, 461 +/- 337, 16 +/- 21, and 40 +/- 38 nmol/l, and those found the next morning, 16 h later, were 18 +/- 12, 322 +/- 213, 9 +/- 10, and 20 +/- 27 nmol/l. The good relationship (r = 0.84) found between MTBE exposure and postshift excretion suggests that urinary MTBE can be used for biological monitoring of exposure, but at the present low level of exposure the corresponding metabolite TBA is not equally reliable. The determination of MTAE and its metabolite TAA in urine is sensitive enough to detect the low degree of exposure to MTAE, but in this study the data were too scarce to allow calculation of the correlations due to very low levels of MTAE exposure.

Changes in neuropsychological symptoms and moods among tanker drivers exposed to gasoline during a work week.

The purpose of this study was to investigate changes in the neuropsychological symptoms and moods among tanker drivers during a work week and the associations of the changes with exposure to gasoline (including 10% methyl-tert-butyl ether). The target group for the study consisted of 101 road tanker drivers from three Finnish oil companies in various parts of Finland. The control group consisted of 100 milk delivery drivers from two milk companies from the same localities. Interviews were conducted before the work week and at the end of the same work week. Standardized symptom questionnaires were used to elicit responses to questions about symptoms and moods. In the questionnaires tanker drivers scored significantly higher in the fatigue scale at the end of the work week than before the work week. Our findings show that tanker drivers with long exposure to gasoline during the work week developed significantly higher changes in fatigue scores than drivers with short exposure. During the exposure situations, 20% of tanker drivers reported acute symptoms (headache, dizziness, nausea, dyspnoea, irritation of saliva excretion) at the end of work week voluntarily. These symptoms have been connected, with MTBE (methyl-tert-butyl ether) exposure, among others. Exposure to MTBE during the work week can be reason for acute symptoms among the tanker drivers in this study.

Neuropsychological symptoms among tanker drivers exposed to gasoline.

The purpose of this study was to investigate the occurrence of neuropsychological symptoms over periods of one week and one month among tanker drivers as related to exposure to gasoline (methyl-tert-buthyl ether 10%). Milk delivery drivers acted as controls. In addition to exposure to gasoline, age, chronic diseases, perceived health, working time, work history in the occupation of driver and alcohol consumption were scrutinized for their associations with the symptoms. The target group for the study consisted of 101 road tanker drivers from three Finnish oil companies all around Finland. The control group was 100 milk delivery drivers from two milk companies from the same localities in Finland as the tanker drivers. Standardized symptom interviews were conducted for all drivers. The differences in the occurrences of neuropsychological symptoms between tanker drivers and controls were not statistically significant. The age of the drivers, chronic diseases and perceived health were connected to the occurrence of symptoms among drivers. The results of this study do not exclude the possibility that vulnerable groups exhibit an increased sensitivity to gasoline.

Exposure of tanker drivers to gasoline and some of its components.

The purpose of this study was to measure the exposure of road tanker drivers at work to gasoline and some of its components. The occupational hygiene measurements were made in two depots (one in northern Finland and the other in southern Finland) and in 11 service stations of a Finnish oil company during the loading and delivery of road tankers. Of the 21 measurements made, four were taken during top submerged loading of the road tankers and six during bottom loading at the depot. Eleven measurements were made during delivery at service stations. The duration of measurements varied from 10 to 44 min. The exposure of road tanker drivers to C3-C11 hydrocarbons of gasoline was under 300 mg m-3 during bottom loading measurements and during top loading exceeded 300 mg m-3 two measurements (50%). During delivery at service stations the exposure to C3-C11 hydrocarbons of gasoline exceeded 300 mg m-3 in four measurement (36%). The exposure of road tanker drivers during delivery depended mainly on the distance between working area and the emission point of discharging vapours from the tank, vents and wind direction. The mean exposures of road tanker drivers to benzene during loading and delivery were 1.1-18 mg m-3 in various situations. The mean exposures to n-hexane, to toluene and to xylene were 0.7-6.0, 1.4-11 and 0.8-4 mg m-3, respectively. The exposures to methyl-tert-butyl ether were between 13 and 91 mg m-3. All measurements were made during the summer. However, the temperature varied between 4 and 22 degrees C.

Neuropsychological symptoms among tanker drivers with exposure to solvents.

The purpose of this study was to measure the exposure of road tanker drivers to organic solvents at work, and to study, using questionnaires, how many symptoms drivers have which might be caused by exposure to solvents. The target group for the study was all the road tanker drivers of a Finnish oil firm (n = 61 men). There were two control groups from the same firm. One control group included workers who were occasionally exposed to solvents at work (n = 56 men). The other group included workers who had no exposure to solvents (n = 31 men). Industrial hygiene measurements were made in two oil depots (n = 20). The drivers' personal exposures to organic solvents during loading of road tankers were remarkable. In seven measurements (50%) during top loading, the exposure exceeded the Swedish TLV(8h). In symptom questionnaires, the drivers had more acute symptoms which might be caused by solvent exposure compared to the control group who had no exposure. The most remarkable differences were in the symptoms of fatigue, depression, hostility, listlessness and uncertainty. Drivers had fewer symptoms which might be caused by long-term exposure to solvents than control groups. Furthermore, the differences between groups were not statistically significant.