Effect of aftermarket automobile window tinting films on driver vision

This study was conducted to determine the level of automobile window tint t hat causes a significant reduction of vision for automobile drivers. Contra st sensitivity was measured on 20 participants, of whom 10 were age 20 to 2 9 years and 10 were age 60 to 69 years, through a stock automobile window ( control) and two windows darkened with plastic film. For the younger driver s, a car window with 37% transmittance did not significantly reduce contras t sensitivity, but a darker tint of 18% transmittance reduced contrast sens itivity at higher spatial frequencies. For the older drivers, a tint of 37% transmittance significantly reduced mid-to-high spatial frequency contrast sensitivity. The typical state standard (no tint with less than 35% transm ittance) would thus seem to be appropriate for younger drivers; however, fu rther examination of the standard may be necessary in regard to older drive rs. Actual or potential applications of this research include guidelines an d regulations regarding tinting of automobile windows.