Exposure/Risk Assessment of Employees in Gasoline Refueling Stations with and Without the Efficacy of Vapor Recovery Systems in Mexico

Abstract

Concerns regarding the health risks associated with employe exposure to volatile chemicals during gasoline refueling necessitates rigorous investigation and effective countermeasures. This study aims to evaluate the efficacy of vapor recovery systems in mitigating exposure risks during gasoline refueling. Employee exposure to volatile organic compounds, aldehydes, carbon monoxide, and fine particulate matter (PM_2.5) was assessed at gasoline stations with and without vapor recovery systems. Three stations each from the State of Mexico and Mexico City, equipped with gasoline vapor recovery systems, were compared with three stations in Guadalajara lacking such systems. The exposure concentrations (mean ± standard deviation) to benzene in Guadalajara, the State of Mexico, and Mexico City were 45 ± 29, 24 ± 20, and 18 ± 15 μg/m³, respectively, which were significantly higher than the background atmospheric concentrations at 1.6 ± 0.56, 0.72 ± 0.083, and 0.65 ± 0.14 μg/m³, respectively. Similarly, the exposure concentrations of toluene, ethylbenzene, and xylenes at gasoline stations were significantly higher than the background atmospheric concentrations. However, the exposure concentrations of formaldehyde and PM_2.5 were similar to the background atmospheric concentrations. The excess cancer risks due to benzene exposure were estimated at 1.2-4.2 × 10^-5, 0.63-2.2 × 10^-5, and 0.46-1.6 × 10^-5 (mean) and 0.42-1.5 × 10^-4, 0.29-1.0 × 10^-4, and 2.4-8.6 × 10^-5 (maximum) in Guadalajara, the State of Mexico, and Mexico City, respectively. The risk to employees in gasoline stations was reduced by 47-61% in service stations with gasoline vapor recovery systems.

Keywords: BTEX; carbon monoxide; formaldehyde; gas station; personal exposure; vapor recovery system.

Figure 1

(a) Refueling volume of gasoline and (b) number of refueled cars for 2 h per employee. G: Guadalajara; SM: State of Mexico; CDMX: Mexico City (Ciudad de México).

Figure 2

Personal exposure and background concentrations of volatile organic compounds at gasoline stations. (a) Benzene, (b) toluene, (c) ethylbenzene, (d) m,p-xylene, (e) o-xylene, and (f) formaldehyde. GB, SMB, and CDMXB indicate the background sampling locations in Guadalajara, the State of Mexico, and Mexico City. The bold bar indicates the mean value, and the thin line indicates the standard deviation (SD). Glay and blue bars indicate the personal exposure concentrations of employees and the background (outdoor) concentrations, respectively.

Figure 3

Personal exposure and background concentrations of carbon monoxide (CO) at gasoline stations. The bold bar indicates the mean value, and the thin line indicates the standard deviation (SD).

Figure 4

Personal exposure and background concentrations of PM_2.5 at gasoline stations. The bold bar indicates the mean value, and the thin line indicates the standard deviation (SD). Glay and blue bars indicate the personal exposure concentrations of employees and the background (outdoor) concentrations, respectively.

Figure 5

Correlations between exposure concentrations and refueling volume.

Figure 6

Correlations between exposure concentrations of benzene and toluene, toluene and m,p-xylene, and formaldehyde and CO.