Homeless people in California are already a vulnerable group, often struggling with poor health, trauma and deep poverty before they lose their housing, according to a new study on adult homelessness.

The study released Tuesday by the University of California, San Francisco attempts to capture a comprehensive picture of how people become homeless in California, and what impeded their efforts at finding permanent housing. The representative survey of nearly 3,200 homeless people found that when they lost housing, their median household income was $960 a month, and for renters on leases it was $1,400 a month, of which on average half went to rent.

Homelessness is a national crisis, and all too pervasive in California, where an estimated 171,000 people — or 30% of all homeless people in the U.S. — are homeless. Political leaders are divided over how to address the crisis, with some, including Democratic Gov. Gavin Newsom, favoring tent encampment sweeps and a tough-love approach toward those with mental health and addiction issues.

It it not groundbreaking news that the state's exorbitant housing costs are a major driver behind homelessness, but researchers at the UCSF’s Benioff Homelessness and Housing Initiative hope that the study will strengthen public support for policies that focus on offering housing and emergency rental assistance — rather than policies emphasizing punishment or stigma.

“People are homeless because their rent is too high. And their options are too few. And they have no cushion,” said Dr. Margot Kushel, initiative director and lead investigator. “And it really makes you wonder how different things would look if we could solve that underlying problem.”

Kushel's team surveyed nearly 3,200 adults around California, and followed up to conduct in-depth interviews with 365 people, between October 2021 and November 2022.

The study found that Black people made up 26% of the homeless population in a state where they are only 6% of the general population. About 90% of participants were living in California when they became homeless. Half reported an inability to work due to age, health or disability. The median length of homelessness was a little under two years.

More than a third of adults surveyed met the criteria for chronic homelessness, meaning they had a disabling condition and were homeless for at least 1 year — or were homeless four times in the previous three years totaling more than 12 months.

In Los Angeles in 2015, Sage Johnson's mother was evicted from their apartment when she was unable to meet rent that had increased to $1,200. In disability pay, she received about $1,340 a month. She bounced around, from LA's notorious Skid Row to various convalescent homes while her daughter lived at a shelter.

Later, Johnson, 28, was able to place her mother in a home, where she stayed for about two years. In 2018 though, her mother died from a debilitating stroke.

Johnson, who now has stable housing, wishes she could have done more.

“But in the end, she did have a bed. She was inside. She didn’t have any more strokes outside. And she was able to regenerate and rejuvenate and restore some of her life while in the convalescent home,” said Johnson, a co-chair for one of the study's advisory boards.

Among study participants, substance abuse and issues with mental health were common and predated becoming homeless. Of those surveyed, 45% reported current, regular use of cocaine, amphetamines and opioids or heavy episodic drinking. Participants described how heavy substance use contributed to losing their homes, but also how methamphetamine usage allowed them to stay alert to protect themselves from assault or theft.

Nearly half of the adults surveyed were not on a lease in the six months prior to becoming homeless, and had likely moved in with family or friends, contributing to rent when they could. Nearly a quarter cited conflict among housemates, desire for more space or not wanting to impose any longer on family and friends as primary reasons they left.

On average, people surveyed who were not on leases received only one day of warning before needing to move out.

Among people on rental lease agreements, more than 20% cited income loss or reduction as the primary reason they lost housing. “So it wasn’t so much that their housing costs increased, it’s that they could no longer keep up with it,” said Kushel.

California ranks as the most unaffordable state when it comes to housing, according to an annual report by the National Low Income Housing Coalition. A person earning an hourly minimum wage of $15.50 would have to work nearly 90 hours a week to afford the statewide average for a modest one-bedroom rental, which is nearly $1,800 a month, the coalition states.

The study was requested by Newsom's administration, which has made addressing homelessness a priority, but the state did not fund it so didn't play a role in analyzing data or interpreting the findings.

The report makes many recommendations, including deep expansion of rental assistance and pilot programs to facilitate shared housing for people seeking to get out of homelessness — and a rental stipend program for people living temporarily with family or friends.

Johnson said she hopes the public will find the report's findings to be evidence that tax dollars are being put to good use in social safety net spending. She also hopes that people will support robust mental health and addiction treatment services along with affordable housing options.

“I don’t want to set anyone up for failure,” she said. “And I’m sure many of my peers can agree that folks need time to practice going back to, like, regular society life.”