One in five websites are being blocked by filters designed to prevent children viewing adult content, according to a study by Open Rights Group. And that's regardless of whether or not they contain any harmful material at all. The blocked sites have included everything from feminist sites like Jezebel and SheRights, political blogs like Guido Fawkes and one by a Syrian blogger and even a site that sells Porsches.

At the start of the year, UK internet service providers (ISPs) began to automatically impose these adult-only filters on new broadband customers unless the users opt out. The filtering will extend to all existing customers by the end of the year. It's all part of David Cameron's plan to limit household access to adult material like pornography and protect the web for kids – and so far, all major ISPs have complied. 

Open Rights Group launched a project called Blocked which analyses how these new filters work. The service looks at internet service providers such as BT, Plusnet, Sky Broadband and Virgin Media to establish whether or not these providers are allowing access to sites. You can even check to see if your site is blocked here. Dazed is safe for now – thanks, internet gods!

However, Pornhub is banned by most internet service providers (no shit) and the streaming site Putlocker is banned on Sky. But site blocking varies from ISP to ISP; the gross-out Fuck Yeah Strange Shit Tumblr, for instance, is blocked only by BT. Similarly, there's no reason why a site like SheRights would have been banned by any ISP – unless ISPs consider women's rights as constituting explicit material.

"We are concerned with the message that blocking our site sends: that pro-woman, pro-equality, pro-human rights subject matter is somehow offensive, inappropriate or otherwise problematic," SheRights editor-in-chief Maureen Shaw told Wired. SheRights is now back up online, while other bloggers like Guido Fawkes have only seen their blogs reinstated after kicking up a fuss about the ban on social media. 

Check on Blocked to see if your site is unfairly losing out on viewers. Is this internet censorship taken too far?