If you’re a publisher that relies on digital ad revenue—and the vast majority of news sites fall into that category—you will have a new problem to worry about in February: That’s when Google starts blocking ads by default for users of its Chrome browser.

The fact that Google planned to make this move was first reported earlier this year by The Wall Street Journal, but the exact timing was unknown. On Tuesday, the web giant said in a blog post that it will start blocking sites on February 15.

ICYMI: People are not happy with Twitter right now

The company says this is an attempt to clean up the state of online advertising, which is awash in pop-ups, interstitials, auto-playing videos, and other clutter. And it says it will only block ads that fail to meet guidelines set by the Coalition for Better Ads (of which Google is a member).

The blocking also comes with a nuclear option: If a site falls below a certain threshold for bad advertising for 30 days, Google will block all of the ads on the site until it takes action to fix whatever problems have been reported.

Google’s motive may be to clean up the web, but some are concerned that a company which already controls a huge proportion of the digital ad market (about 40 percent according to recent estimates) is blocking ads by default in Chrome, which also happens to have the lion’s share (about 50 percent) of the world’s web-browser market.

Sign up for CJR 's daily email

ICYMI: Explosive BuzzFeed scoop raises eyebrows

It’s unclear how much revenue publishers stand to lose from these moves, but Google isn’t the only one taking a stricter approach to advertising: Apple’s latest update to iOS blocks sites from collecting certain types of data on users, which advertisers use to target ads.

Here are a few more links:

Click here to submit : Google says offending sites that are penalized by its default blocking can ask for a review, and if they pass their ads will be shown again.

: Google says offending sites that are penalized by its default blocking can ask for a review, and if they pass their ads will be shown again. No countdowns : The Better Ads Standards page defines what ads are unacceptable, including pop-ups, auto-play videos, pre-stitials that use a countdown before you can view content, and ad density that exceeds 30 percent of the page.

: The Better Ads Standards page defines what ads are unacceptable, including pop-ups, auto-play videos, pre-stitials that use a countdown before you can view content, and ad density that exceeds 30 percent of the page. 1-800-Antitrust : When the news first broke about Google’s plans, Cornell law professor James Grimmelmann said that they could raise potential antitrust concerns.

: When the news first broke about Google’s plans, Cornell law professor James Grimmelmann said that they could raise potential antitrust concerns. Is this okay or not? Judging by some of the comments on Google’s support forums, some website owners are having a hard time figuring out what they have done wrong.

Other notable stories:

Leaked documents show that Mashable, which agreed to sell itself to Ziff Davis recently for $50 million (about 20 percent of its previous value), was losing money at a prodigious rate. The company lost over $4 million in just three months.

A Vox feature tells the story of women who decided to get out of journalism because of the sexual harassment they faced. Former Washington Post reporter Kate Havard left because, “I decided I didn’t want to have to fend off gross sources for the rest of my life.”

Bloomberg says billionaire Carlos Slim, who helped bail out The New York Times by lending the company $250 million in 2009, plans to sell about half the shares he got in the paper as a result of that deal, taking his stake from 15 percent to about 8 percent.

Diana Moskovitz writes for Deadspin about what it was like to work for the NFL Network, the media arm of the National Football League. In addition to the long hours and working on shows like Behind the Pom-Poms, the job included having to make calls and gather documents whenever a player got arrested.

Facebook’s test of a split news feed, in which news sites appear in a separate feed, caused traffic to fall by as much as 60 percent at some Slovakian news sites, but fake news providers weren’t affected as badly, according to journalist Filip Struhárik.

A report from PricewaterhouseCoopers says that the number of people who subscribe to Netflix is now equal to the number who pay for traditional cable, and the accounting firm expects the former to continue to outpace the latter.

ICYMI: 8 strategies for saving local newsrooms

Has America ever needed a media watchdog more than now? Help us by joining CJR today

Mathew Ingram is CJR’s chief digital writer. Previously, he was a senior writer with Fortune magazine. He has written about the intersection between media and technology since the earliest days of the commercial internet. His writing has been published in the Washington Post and the Financial Times as well as by Reuters and Bloomberg.