What do Mark Zuckerberg’s private security officers and drivers of school buses, Uber cars and the many construction vehicles sitting curbside on Palo Alto’s streets have in common?

They’re all idlers — of parked vehicles. And to the dismay of many city residents, their idling vehicles spew pollutants into the air that could harm people and the environment.

Neilson Buchanan, who lives just north of downtown, said he sees idling vehicles all over town.

One day last week, Buchanan noticed shuttles and vans idling as they waited at the Caltrain stop for passengers; a bus idling as its passengers toured the Apple store; and Uber and Lyft drivers parked in the shade near his home waiting for customers during the evening rush hour.

“Not only do I see them, I can hear them and smell them,” Buchanan said. “The noise and smell pollution from diesel trucks is unmistakable. It’s kind of annoying to hear all the rumble, rumble, rumble.”

Diesel trucks and buses aren’t the only culprits. Even Facebook CEO Mark Zuckerberg’s private security detail has been outed.

Norm Beamer, president of the Crescent Park Neighborhood Association, said some residents were concerned enough to approach the private security officers who sat outside Zuckerberg’s home in idling vehicles around the clock.

“I think people understand why he needs security people 24 hours a day, and some neighbors actually like the security because they feel it makes the neighborhood less vulnerable to burglaries and such,” Beamer said. “But people don’t like the idea of the cars running with the engines on. The optics of that are not very good in light of concerns about global warming.”

Residents say the officers seemed to have ceased idling in recent days, according to Beamer.

A spokesperson who handles personal communication for Zuckerberg and his wife Priscilla Chan said by email Wednesday: “The security team takes measures to reduce idling as much as possible, from using batteries to power all of their devices to limiting how often they power their vehicle — approximately 1 out of every 8 hours.”

The spokesperson also said the security team has long taken measures to reduce idling, but redoubled its efforts after hearing from neighbors.

Shelly Gordon, who serves on the executive committee of the Loma Prieta chapter of the Sierra Club, says Palo Alto city leaders can help solve the problem by adopting a vehicle anti-idling ordinance.

The ordinance could ban vehicles from idling for longer than one minute, unless they’re waiting for traffic lights to turn green.

Such an ordinance would improve air quality and human health, lower carbon emissions, protect the environment and reduce oil and gas consumption, Gordon said in a letter to the City Council.

Idling vehicles are seemingly less harmful than moving vehicles, but they have a negative impact, too, Gordon noted.

“Idling vehicles emit more than 40,000 tons of carbon every day in the United States,” Gordon said. “This equates to $13,444,400 wasted on 3.8 million gallons of fuel.”

“Besides emitting carbon, idling cars effuse all kinds of particulate matter,” Gordon added. “It gets lodged in our lungs and it stays there.”

Vice Mayor Liz Kniss and council members Karen Holman, Eric Filseth and Tom DuBois agree the city should take some kind of action on the issue. They submitted a colleague’s memo for review last week and hope the full council can tackle the topic after summer break.

Holman, who makes it a point to turn off her engine when she’s waiting too long in a drive-thru, says it wouldn’t be practical to have drivers do the same at stop lights. But she would back a city ordinance that applies to idling construction vehicles.

With so many construction projects ongoing in Palo Alto at any given time, such an ordinance would go a long way, she said.

“We understand emergency vehicles have to keep engines running,” Holman said. “But I think most of our experience is seeing people sitting in the car talking on the phone.”

Council members say an anti-idling ordinance would help the city make headway on its Sustainability/Climate Action Plan goal of reducing carbon emissions by 80 percent from 1990 levels by the year 2030. Palo Alto also is trying to reduce the number of people driving alone in the city and considering other ways to reduce car travel, such as eliminating free public parking.

The city emitted 780,900 metric tons of carbon dioxide and similar pollutants in 1990, according to its action plan. This means that the city’s goal is 156,180 tons.

Filseth said the city is a little over a third of the way there through transportation, energy and waste-reduction initiatives.

Reducing curbside idling by cars and trucks could reduce transportation-related emissions by 1,000 tons or more per year, and every bit helps, Filseth said.

“This would be a modest but non-negligible contribution to the target, and we think it can be achieved simply and inexpensively,” Filseth said. “Just education alone would probably achieve most of it.”

Sierra Club members say the mission should be to inform people they are in charge of carbon emissions. They also would like to see Palo Alto join the Idle Free Bay Area campaign, in conjunction with the Spare the Air effort.

Idle Free Bay Area wants to dispel myths such as how vehicles are harmed if the engine is not warmed up through idling or that shutting off and restarting vehicles hurt an engine.

Thirty seconds of idling actually uses more fuel than restarting the engine, according to the group.

Gordon said she envisions the ordinance as an opportunity to educate people. Cities with anti-idling ordinances often hand out a few warnings and brochures to drivers idling their cars before citing and fining them, she said.

In the Bay Area, Gordon said she often hands out postcards with information about idling to drivers she sees at shopping centers and schools.

Earlier this year, students Andy Zeng, Rachel Loewy and Tanli Su, members of the Sierra Club Youth Climate Action Leadership Team, monitored and educated parents and students at Hoover Elementary School about idling.

Over a two-week period, the students monitored parents picking up students and counted 162 of them idling for more than 60 seconds and about 40 for more than 10 minutes.

To address this issue, the students handed out pledge cards for parents to sign.

In a video the students produced and posted on YouTube about their work, Loewy says that idling wastes gas and money, and wears down car engines. The students showed the video during a Palo Alto council meeting in May.