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This paper presents a review of the effects of fog on visibility during nighttime driving conditions and the factors influencing the performance of a front fog lamp. The effects on visibility due to beam pattern characteristics, mounting height, and lamp aim are studied using current mathematical models for fog veiling luminance, target luminance, and target contrast. A comparison is made of two different fog lamp photometry standards to show how each performs in terms of fog veiling luminance, target contrast, and glare for the opposing driver. The effects of varying the vertical aim of each fog lamp standard are studied in order to make conclusions about the correct lamp aim and tolerances required for fog lamp aiming. The effects of fog lamp mounting height and driver position are studied. Conclusions are made concerning optimum mounting height, aim, and beam pattern for fog lamps for vehicles with different driver positions.