Alec MacGillis was out for a run in Baltimore the other day when he noticed something else running.

A bunch of cars were idling at the curb, all of them burning fossil fuels and blasting the air conditioner to keep their occupants cool.

That got him a little hot, and so MacGillis – who is an award-winning journalist for ProPublica, a former Washington Post staffer, and a friend – sounded off about AC idlers on Facebook.

“Self-righteous scold alert,” he began. “I just went running through prosperous, Paris-Accord-supporting North Baltimore and lost count of how many people I saw sitting in parked cars at the side of the road with the engine and the AC running and their heads bent in the penitential pose down towards the glowing phone.

“I really don’t get this.”

Neither do I.

But you see it all the time, and not just in neighborhoods where people also cover their Volvos in bumper stickers saying “Climate Change is Real.” Versions of this blithe ignorance can also be found outside schools that host fundraisers to save the rain forest once a year while lines of gas-hogging SUVs – sometimes one per child – line up daily to drop off students.

Idling in a car with the AC on – especially because you can’t get enough of the late night show highlight reel – isn’t very cool. But it’s admittedly tempting, especially on days like Monday and Tuesday when the Capital Weather Gang is forecasting a chance of record-breaking heat in D.C.

Research suggests that idling from all vehicles wastes about 6 billion gallons of fuel a year, about half of which can be attributed to cars, the federal government says. That also translates into the release of about 30 million tons of greenhouse effect-inducing carbon dioxide. By comparison, a typical coal-fired power plant emits about 3.5 million tons of CO2 per year, the Union of Concerned Scientists says. As the U.S.  Department of Energy puts it, getting people to reduce idling is low-hanging fruit in the campaign to reduce waste and pollution.

Several jurisdictions – including New York City, Maryland and the District of Columbia – have enacted laws that penalize unnecessary idling.  In D.C., commercial vehicles are not allowed to idle for more than three minutes while parked, stopped or standing. But the law – which carries a $1,000 penalty – also exempts non-commercial personal vehicles. Maybe that should change.

On the other hand,  not everyone cheered Alec’s self-described rant.

“If the house wasn’t full of screaming children and husbands reminding me of chores I need to do instead of being on my phone, maybe I’d go there,” a person responded. “Meanwhile, the cool quiet of the car is paradise.”

Another wrote: “Alec! It’s over 90 degrees today outside today. Let it be” – punctuated with a smiley face emoji.

But Alec could not.

“Resist the engine-on, zone out!” MacGillis wrote.

Right on.

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