DUBLIN: Ad blocking has become a "viral phenomenon" with lost advertising revenues doubling every year according to a new report.

The Cost of Ad Blocking, a joint report from PageFair, a provider of adblock solutions to publishers, and Adobe, said that the number of ad block users worldwide had increased by 41% in the past 12 months.

"Ad blocking has grown virally along a classic S-curve to 50m+ ad blocking users at the end of 2012, and onward to 198m at the end of Q2 2015," Dr Johnny Ryan, PageFair's head of ecosystem, told Business Insider.

He explained that most users find out about ad blocking by word of mouth and through their own online research. "Ad blocking is a viral phenomenon that will continue," he stated.

In the US, ad blocking grew by 48% between Q2 2014 and Q2 2015 to 45m monthly active users (MAUs), or approximately 16% of the US online population. In Europe, ad blocking grew by 35% during the same period to 77 million MAUs, of which 12m were in the UK.

PageFair has tracked the growth of ad blocking for three years, and measures over one billion ad blocking hits every month across its 3,000+ client websites to determine the types of content most affected: "websites that cater to young, technically savvy or more male audiences are significantly worse affected," it said.

With some websites impacted with up to 27% lost ad inventory, it suggested that ad blocking now poses an existential threat for the future of free content on the internet, especially as the practice starts to spread from desktop to mobile.

In the US ad blocking cost an estimated $5.8bn in lost revenues in 2014, a figure projected to rise to $10.7bn in 2015 and $20.3bn in 2016.

Globally, some $21.8bn will be lost in 2015, increasing to $41.4bn in 2016.

"It is tragic that ad block users are inadvertently inflicting multi-billion dollar losses on the very websites they most enjoy," said Sean Blanchfield, PageFair CEO and co-founder, as he warned that the business model supporting the open web was in danger of "collapse".

Among US consumers not currently using ad blocking software the main reasons given for possibly adopting the technology were personal data being misused (50%) and an increase in the number of ads from that currently encountered (41%).

Data sourced from Business Wire, Business Insider; additional content by Warc staff