When disasters from hurricanes to wildfires swept the U.S. this fall, mental health start-up Talkspace turned to Facebook for free advertising to reach victims.

But while Talkspace CEO Oren Frank says he’s grateful for the donation, he was left with mixed feelings about accepting the ads.

Facebook is a near-necessity for companies trying to rapidly reach disaster victims, including Talkspace, which offers online therapy, Frank said. But Frank believes Facebook could take a more active approach when it comes to stewarding the mental health of its users.

“Facebook are currently insisting that they are ‘just a platform’ and are trying hard to stay away from any content and service plays. My two cents is that Facebook will have to change this approach. It’s not sustainable and also it is not the right thing to do,” Frank said. “Maybe, hopefully, in time, they’ll acknowledge their responsibility for the well being of people who spend so many hours using their services.”

Talkspace, which has raised at least $60 million from investors like SoftBank to power online chat-based therapy, offered a free Facebook group to help hurricane survivors, moderated by around 20 Talkspace representatives. There were groups for both Hurricane Harvey and Hurricane Irma, and Facebook offered a “very nice number” of free ads to promote the groups.

These are moderated support groups — not a medical service or traditional therapy. At their peak they had over 1,000 people, Frank said.

“The support groups hosted conversations on a wide variety of topics, including ‘What do I do if my eating disorder has been triggered by the stress of the storm?,’ as well as ‘How do I process my survivor’s guilt?’ and ‘The best ways to handle anxiety when applying for FEMA benefits’,” Frank said.

But Facebook groups like these could reveal who has shown interest in working with a mental health professional — which could be considered a very private aspect of health and safety after trauma.

“We know that 20 percent to 25 percent of any population will suffer from mental illness every year. This means that in any given time, over 400 million using Facebook are suffering from a clinically diagnosable mental health issue,” Frank wrote in an email to CNBC. “I think Facebook, with their unlimited data capabilities, knows this very well, and it’s highly likely they also know exactly who the suffering users are.”

Facebook confirmed it provided credits for Talkspace’s ad campaign but could not disclose a dollar amount for the donation.

After the recent shooting in Las Vegas, Talkspace opted not to use Facebook groups to help employees of Live Nation, Mandalay Bay, the first responders, and the concert goers. The company is instead offering 100 months of free Talkspace therapy, which had to be done on a platform compliant with HIPAA privacy laws, so Facebook would not have suited.

But Talkspace went back to Facebook groups when it came time to reach victims of recent wildfires in northern California.

“We’ve decided that extending help is the highest priority,” Frank said. “Facebook has its own set of considerations which I’m not a part of, but knowing many people who work there, I believe they’re driven by doing the right thing and help their users — their willingness to help us is one sign of this.”

It’s fairly rare for advertising to be donated to a for-profit company, although it makes sense in the case of disaster, said Anthony LaFauce, vice president of Digital at Porter Novelli, and an adjunct professor who teaches social media strategy at American University. BetterHelp, a competing start-up, said it is also providing free services for those impacted by both Harvey and Irma, but a spokesperson said “it doesn’t look like we’re supporting the Facebook initiative.”

There’s no clear guidance for companies like Facebook and Talkspace when it comes to using health-related data to target advertising.. What happens with self-disclosed health-related data on social media is highly regulated in some ways, but is a grey area in others, LaFauce said.

“[The best practice on ad targeting] walks the balance of counseling and mental health treatment,” LaFauce said. “Fifteen years ago, you put yourself in the newspaper, it becomes public. We’ve been trying to put that into place, but it’s hard to understand, with social media, you’re entering a public conversation.”

Facebook has made changes to its approach to mental health this year, including more sophisticated outreach to users discussing self-harm and suicide and an investment in its safety and security team. The company also matched more than $1 million in donations for Hurricane Harvey, and donated $1 million to local organizations to help with wildfires in California.

Frank said Talkspace donates at least 500 months of free therapy to audiences and populations that can’t afford it each year. But he said would not deliver therapy on a platform like Facebook that “isn’t ours and is not HIPAA compliant.”

“Maybe, hopefully, in time, they’ll acknowledge their responsibility for the well being of people who [spend] so many hours using their services. I hope so,” Frank said.