Robin McKinney wasn’t wearing the right shirt. She also didn’t have all of her supplies. But the night was warm for mid-November, and that had gotten her worried. So she went anyway, pulling up to a Southeast Washington park hit hard by synthetic drugs, trying to make a difference on an issue she believes is usually met with indifference.

The District had just seen another spike in K2 overdoses, this one smashing previous levels, with 1,054 overdoses in September alone. And McKinney, whose activism represents the latest chapter in the city’s ongoing struggle against the drug, wanted to get information to the people most in peril.

Over the past two years, abuse of K2 — a group of synthetic cannabinoids whose chemical composition varies — has increased among the homeless, according to city officials and social workers. The fallout has been visible in some pockets of the city, where users writhe from overdoses on street corners, in homeless shelters and in parks like this one, near the intersection of Martin Luther King Jr. and Malcolm X avenues, terrifying onlookers.

Last month, the city passed legislation outlawing certain categories of chemical compounds, easing prosecution of dealers who had consistently tweaked their composition of the drug to stay ahead of law enforcement. City officials have also cracked down on stores illegally selling synthetic drugs, strengthening penalties for doing so.

“It’s a drug of convenience,” said Tanya A. Royster, director of the D.C. Department of Behavioral Health, adding that overdoses rarely result in death, killing just eight people since the beginning of 2017. “Whoever’s looking for something convenient, and in our community, that happens to be the [chronically] homeless male population, predominantly.”

The drug may appeal to homeless people for a number of reasons, according to social workers who serve them.

For one, it’s extraordinarily cheap, going for as little as $1 or $2 for a joint, which can get two or three people high. It’s also easy to produce, even in kitchen sinks and garages. That combination — cost and widespread availability — make it particularly attractive to the chronically homeless who struggle with addiction, especially when they’re out of their drug of choice.

Kate Wiley, an official with So Others Might Eat, which feeds between 800 and 1,000 homeless people every day, said K2 has become a bigger presence at the dining hall. Disruptions from people who are high have increased. Homeless people are reporting to staff that K2 dealers are waiting outside. And some clients simply nod off while they’re at the table.

“It’s kind of like they’re narcoleptic,” she said. “Our staff has noticed a lot more people passing out, for lack of a better word, and that’s one of the effects of K2.”

Other effects: rapid heart rate, high blood pressure, nausea and slackened facial features.

Christy Respress, executive director of Pathways to Housing DC, which transitions the homeless into housing, said the drug’s recent impact on her clients has been “huge.”

That’s why McKinney, 45, comes every week to this spot at the park, where homelessness and drugs collide, with seven suspected K2 overdoses on one day in September. She normally arrives wearing a T-shirt that says “Kill K2,” but on this day, she showed up in a black coat carrying packs of water to battle the dehydration that can trigger an overdose, as well as reams of fliers warning of the harms of K2.

They are harms she knows better than most.

In the spring of 2015, her son, then in his 20s, overdosed. He and a friend were outside smoking, and first the friend passed out, followed by her son, who was taken to a hospital. Frantic days passed without her knowing where he was, until she discovered he was at the hospital, where he stayed for weeks, the friend even longer.

The story of McKinney’s son, who was on probation at the time for a minor charge over riding a dirt bike, was typical of that period, city officials say. One of the most alluring aspects of the drug is that each batch can carry a different chemical punch, so people on probation who faced regular drug tests smoked K2 to try to pass them. The “probation pack,” some called it on the street.

Educational efforts by city officials about the dangers of the drug — along with the legalization of marijuana, say Southeast residents and activists like McKinney — made K2 less attractive to city youths.

But what about the people for whom it remains attractive?

Those were the people McKinney thought of this past summer, as the toll of overdoses climbed higher. In the past few months, she estimates, she saw as many as 20 people lying out on the street, overdosing — “zombified.” She became convinced she had to do something to help, even if it seemed to her that so many people in Congress Heights, where she raised her seven children, were resigned to the presence of K2 as just one more drug to work its way through the neighborhood.

“This community, they accept it,” she said. “They accept it, and I didn’t want to.”

Now, on one more evening trying to get people not to accept it, McKinney, along with a representative from the local Advisory Neighborhood Commission, placed the packs of water and a box of chips, crackers and cookies atop her Camaro’s trunk. They took out a small stack of leaflets. “EMERGENCY ALERT,” they read, warning of how dehydration can exacerbate the danger of smoking the drug. “K2 . . . may lead to overdose or death.”

People in the park and from nearby gas stations started lining up. Some weren’t homeless. Others were.

“You want a bag of chips?” McKinney asked one person.

“You want a water?” she asked another, as the ANC representative, Mike Austin, passed out supplies, too.

“You all know the info I pass out regarding K2,” she said over the clamor, dispensing the fliers. “I pass out these.”

“Who are you?” one person called.

“Just a community activist, coming out to help out,” she called back.

The people took the offerings and retreated into the darkness of the park or to groups standing outside the convenience store. Some weeks, McKinney didn’t know how much she was actually helping the problem of K2. She thought she was. But who could know for sure?

One young person now approached in a winter hat. It was one of McKinney’s young relatives, whom she had watched grow up. The young woman’s eyes were glassy. Her facial features were slack. She was high, McKinney realized — clearly high. The young relative took the food and water and walked away, leaving McKinney worried and feeling helpless.

“You can’t help your own,” she said. “It hurts. I couldn’t even help my own child, and it does hurt.”

But then she was on to the next person, and the next after that. More and more were coming to take the food — and another flier warning of K2’s dangers.

“I notice this isn’t being talked about,” she said. “I want to achieve getting the word out.”

Tyler Blint-Welsh contributed to this report.