The Palo Alto City Council is considering a city ordinance which would reduce light pollution by limiting the types and operating hours of outdoor light fixtures. In an April 7 meeting, the Palo Alto City Council unanimously passed Council member Greer Stone’s motion to consider “new outdoor lighting regulations” in the municipal code.
The motion instructs “staff to return to the council” with a draft of the final ordinance.
The proposal would establish a midnight curfew for outdoor lighting and restrict the temperature of light sources to lower temperature bulbs that emit orange, not blue, light.
Other elements of the ordinance include limits on how much outdoor lighting can spill over onto neighboring properties. Light fixtures would also need to be shielded, meaning an opaque cover must block light from escaping upward into the sky.
If adopted, the regulations would immediately apply to new buildings, while private residences would have up to 10 years to adapt their light sources.
The proposed ordinance also makes exceptions for parking lots, gas stations and similar areas that require lighting at all times.
Limiting outdoor lighting has benefits for human health, energy costs and the environment, but policymakers must also weigh concerns about public safety.
Because Stanford is located in unincorporated Santa Clara County, if the Palo Alto City Council passed the ordinance, it would not apply to the campus.
Rohan Parekh, a second year master’s student in materials science and co-president of Stanford Energy Club, said that light pollution both negatively impacts human health and is energy-inefficient.
Light that artificially brightens the night sky disrupts humans’ circadian rhythms, or their natural sleep-wake cycle. Artificial light, particularly blue light, can disrupt the production of melatonin, the hormone that causes sleepiness.
According to DarkSky, a pro-light ordinance nonprofit, artificial light also disrupts nocturnal animals’ behavior and can disorient birds.
Nightly curfews would also reduce yearly energy consumption.
For Parekh, seeing the night sky is another advantage of light curfews. Growing up in a city, he found it a “bummer” that he could not see the stars.
An October 2024 preliminary study of a light ordinance by the city council’s Planning and Transportation Commission (PTC) predicted no “direct fiscal impacts on the City budget.” Parekh also said that installing lower-temperature bulbs or adding motion sensors are relatively inexpensive.
“You can’t really put a price on human health,” Parekh said.
He further noted that public safety is the number one concern about light curfews. Some streets may require 24/7 lighting, while businesses like restaurants and nightclubs require artificial lighting late into the night.
Bay Area communities with dark sky ordinances include Brisbane, Cupertino, Portola Valley and Woodside. Brisbane adopted its dark sky ordinance in 2024, which applies to new and existing outdoor light fixtures. All lighting in the city does not need to be in compliance until 2039.
Stone did not reply to a request for comment.