By Oliver Darcy, CNN Business

(CNN) -- An attorney representing 10 of the families who lost relatives in the Sandy Hook massacre said on Wednesday that he welcomed YouTube's decision to remove videos denying the shooting. However, he said it was "too late to undo the harm" that has been caused to them by conspiracy theories circulating on the platform over the last several years.

"Sandy Hook happened now nearly seven years ago, and so during that entire time the clients were subject to hostile postings on YouTube that disseminated this false narrative and caused undue harassment, threats, and fallacies as they were trying to heal," the attorney, Josh Koskoff, told CNN Business in a phone interview. "At the same time, better late than never."

The families of the Sandy Hook victims have for years been subject to harassment stemming from conspiracy theories being pushed on YouTube and other social media platforms.

One of the dominant conspiracy theories was that the shooting was a false flag staged to gin up support for implementing gun control measures. Alex Jones, the right-wing conspiracy theorist and InfoWars founder, who was one of the prominent disseminators of that theory, has been sued by Sandy Hook families in both Texas and Connecticut courts.

Jones was banned by YouTube and other social media platforms in 2018. In a sworn deposition taken earlier this year, Jones conceded the shooting was real, and said it was a "form of psychosis" that caused him at the time to believe it was staged.

YouTube, which has faced scrutiny for the spread of hate and harassment on its platform, said on Wednesday it had updated its policies to prohibit videos that deny what it characterized as "well-documented events." The company said in its press release that the policy would apply to the 2012 Sandy Hook elementary school shooting, which claimed 26 lives.

Koskoff said that while it might be too late to be of much help to his clients, the move will help prevent the "additional pain" future families might have to deal with if their loved ones were involved in a shooting and people were posting "outrageous theories" on YouTube.

YouTube's decision was also praised by Lenny Pozner, the father of a Sandy Hook victim who established the HONR network, which monitors the spread of false information online.

Pozner told CNN Business that "it is impossible to calculate the damage that these videos have done." But he added, "We thank YouTube for taking the lead in enacting policy changes that we have been recommending for the past half-decade."

YouTube did not immediately respond to a request for comment.

Both Koskoff and Pozner called for other social media companies to follow YouTube's lead.

"All social media platforms who have not taken this step, should look in the mirror and decide whether they want to continue to facilitate harassment and hate in this day and age where that has serious consequences," Koskoff told CNN.

Pozner added that he too hoped "Twitter and other hosting platforms will follow suit in implementing and enforcing more socially responsible policies."