Google has announced a series of changes to its policies on advertising and hate speech, after several major brands pulled their ads from YouTube earlier this week. In a blog post published on Tuesday, the search company said it will give brands greater control over where their ads appear and more aggressively police “hateful, offensive and derogatory content.”

The announcement comes after an investigation from The Times of London found that ads from the UK government and some prominent companies were appearing alongside extremist YouTube videos, including clips that promoted white nationalism and homophobia. The UK government pulled its advertising from Google and YouTube following the report, and summoned the web company to the Cabinet Office. Major brands such as Audi, Marks and Spencer, and French advertising giant Havas later pulled their ads as well, prompting a public apology from Google’s head of European operations on Monday.

In the blog post published today, Philipp Schindler, Google’s chief business officer, said the company will more aggressively police content that targets or harasses people “based on their race, religion, gender or similar categories.” As Bloomberg reports, Google is broadening its advertising policy on hate speech to cover content that targets vulnerable groups, including people harassed or demeaned because of their country of origin or socioeconomic status.

The company’s ad settings will also exclude “potentially objectionable” content by default, and advertisers will be able to exclude specific sites or channels from their campaigns. Google plans to hire “significant numbers of people” to review objectionable content, Schindler said, and will continue developing machine learning and artificial intelligence tools to expedite the process.

"We believe the combination of these new policies and controls will significantly strengthen our ability to help advertisers reach audiences at scale, while respecting their values," Schindler wrote.

Google and Facebook have come under increased scrutiny in recent months for allowing advertisements to run against extremist content and fake news sites. Both companies have emerged as dominant forces in the digital ad industry, combining to account for more than 60 percent of global revenue in 2015. Industry executives say that although Google’s ad standards are among the strictest, its recent troubles in the UK point to a persistent problem across the market.  

“This is a common problem across the industry,” Jeff Liang, chief digital officer at Assembly, a New York-based media agency, said in an interview Monday. “What we’re seeing with a company like YouTube also dealing with issues like this, is that it’s very difficult to manage these issues because they happen in real time.”

Around 400 hours of video are uploaded to YouTube every minute, according to Google. The company has so far relied on users to flag offensive material, and it has said that 98 percent of reported content is reviewed within 24 hours. In today’s blog post, Schindler said that with increased staffing, resources, and a new escalation plan, Google will “soon be able to resolve these cases in less than a few hours.”

Increased data and automation have made it easier for brands to reach large volumes of consumers or specific demographics. But the complexity of ad exchanges and a lack of oversight have made it harder for them to control where their ads appear. Keyword filters and visual recognition software have allowed companies to keep their ads away from some content, Liang says, but such methods are less effective when it comes to extremist content, which can take a variety of forms.

“You’re not going to see these terrorist organizations label their content as violent,” Liang said. “They’re going to label it in a positive way for whatever goal they’re trying to achieve.”

It is not clear when the changes announced today will go into effect. Havas declined to comment directly on Google’s announcement in an email statement, saying only that the decision to pull its advertising in the UK is “a temporary move,” and that it will not remove ads on a global basis.

“We welcome the swift action Google is taking to address these concerns and the positive impact these assurances will make,” Audi said in an email statement. “Once we have a committed timeframe from Google clarifying when these safeguards will be implemented across the board, we will have a closer discussion with the brand and fully assess our position in the UK.” Representatives from Marks and Spencer did not immediately return a request for comment.

Marc Goldberg, CEO of the ad safety vendor Trust Metrics, said Monday that the UK boycott of Google ads could signal an important shift in the industry, as brands demand stronger safety protections from companies like Facebook and Google. He believes part of this shift is due to social media, which has brought wider attention to even small-scale incidents.

“The industry is misaligned, and the buy side can correct it if they want,” Goldberg said in a phone interview. “The buy side really owns the opportunity to put more strict requests in, and if the supply side is not following suit, then the buy side should, for example, do what Havas did, and stop spending.”

Update March 21st, 10:33AM ET: This article has been updated to include a statement from Audi.