This study examined the level of automobile window tint that causes a significant reduction of vision for automobile drivers. Contrast sensitivity was measured through a stock automobile window (control) and two windows darkened with plastic film on 20 participants: 10 aged 20-29 and 10 aged 60-69. For the younger drivers, a car window with 37% transmittance did not significantly reduce contrast sensitivity, but a darker tint of 18% transmittance reduced contrast sensitivity 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% transmittance--would thus seem to be appropriate for younger drivers; however, further examination of the standard may be necessary with regard to older drivers.
Samenvatting