To better understand why so many people end up homeless in California, a group of researchers conducted a statewide survey, which found that deep poverty and lack of affordable housing are to blame.

For most of the people living on the streets, they lost their homes simply because the cost of housing had become unsustainable, according to the California Statewide Study of People Experiencing Homelessness released on Tuesday.

Researchers at the University of California, San Francisco (UCSF) surveyed nearly 3,200 participants in urban and rural areas across the state and conducted 365 interviews from October 2021 to November 2022.

The findings showed that lost or reduced income, more than addiction, mental health, poor decisions or other factors, was the main cause of homelessness.

In the six months prior to becoming homeless, the survey participants said they were making a median income of just $960 a month. The median rent for one-bedroom apartments in California is $1,898, according to real estate marketplace Zillow.

"People are homeless because their rent is too high. And their options are too few. And they have no cushion," said Margot Kushel, lead author of the report and director of the Benioff Homelessness and Housing Initiative at the UCSF. "And it really makes you wonder how different things would look if we could solve that underlying problem."

Mental health and addiction are common problems among the homeless – two-thirds of the participants reported experiencing depression, anxiety or hallucinations, and other symptoms in the past 30 days; about one-third of them reported using drugs three or more times a week, and one in five people reported regular drug or heavy alcohol use.

The new study also found that the homeless population tend to be older than average and are disproportionately likely to be Black or Native American.

However, to solve the homelessness crisis, the main problem California needs to address is the lack of housing that is affordable for extremely low-income residents, according to the researchers.

The state has just 24 affordable and available homes for every 100 extremely low-income households, according to the National Low Income Housing Coalition.

The Golden State has more than 171,000 homeless residents, accounting for 30 percent of the national total, according to data of the U.S. Department of Housing and Urban Development. 

(With input from agencies)