Background: Light is the first that necessary for any effort. This factor, more than any physical variable, affects human labor. Two properties of cognitive and psychological lighting in the workplace can affect human performance.Objectives: This study aimed to assess the illuminance in CO2 Gas unit of Khuzestan Zam Zam Company, and resolve its light deficiency through artificial lighting design.Materials and Methods: This study is a descriptive-analytical based on survey of natural and artificial lighting sources in the workplace. It also included measurement of lighting levels in 3 shifts, calculating the average illuminance and comparing with recommended values, drawing graphs of results measured illuminance, and finally designing the lighting of the unit by lumen method with room index (Kr). The study was conducted between March and June 2006 and its data were analyzed with 1-way analysis of variance (ANOVA).Results: Mean ± SD level of illuminance in the morning, evening, and night was 211.31 ± 292.07, 182.16 ± 205.16, 67.47 ± 71.10 (lx), respectively. The results showed that there is a significant difference (P<0.001) between average illuminance of 3 shifts of morning (day light), evening, and night (artificial light) and the standard illuminance value (300 lx), which entails the lighting design’s work area for this unit. According to the design of artificial lighting base on the lumen method calculations in CO2 Gas unit, 400, 250 watt Metal Halides and 10585 watt compact fluorescent lamps were required, which their numbers were 610 and 44, respectively.Conclusions: This paper considered the method based on comprehensive surveys of workplace illuminance levels (natural light and artificial light) and design of lighting system as one of workplace physical factors in order to increase the efficiency of the production unit, decrease in carelessness, fatigue errors, and work accident.