Table 2.

Lux level and corresponding real-world examples

Illuminance (lux)	Luminance (cd/m2)	Corresponding environment
1	0.32 mesopic vision	Moonless summer night; or indoor nightlight
4	1.3 mesopic vision	Cloudless summer night with half moon; or outdoor parking lot at night
10	3.2 mesopic vision	60 min after sunset in a city setting; or a bus stop at night
50	15.9 photopic vision	Outdoor train station at night; or inside of illuminated office building stairwell
125†	39.8 photopic vision	30 min before cloudless sunrise; or interior of shopping mall, train or bus at night
250‡	79.6 photopic vision	Interior of elevator, library or office hallway
400	127.3 photopic vision	Office environment; or food court

National Institute of Standards and Technology-calibrated, Extech model EA33 light meters used to provide examples and to set/verify specified light levels used for mobility testing.

^†Analysis incorporates runs at 100 and 150 lux.

^‡200 and 250 lux were combined for analysis purposes; however, no subjects were tested at either of these levels because these levels were not needed to identify any lowest passing or highest failing level.