Ad blocking technology’s impact on online advertising is expected to grow in coming years. Digital marketing researcher eMarketer says that this year 69.8 million Americans will use an ad blocker, up 34.4 percent over 2015. By 2017, 86.6 million people will be using them, a 24-percent year-on-year increase.

In its research, eMarketer defines an ad blocker user as someone who accesses the internet at least once a month through a device with ad blocking software installed.

“Ad blocking is a detriment to the entire advertising ecosystem, affecting mostly publishers, but also marketers, agencies and others whose businesses depend on ad revenue,” says eMarketer senior analyst Paul Verna. “The best way for the industry to tackle this problem is to deliver compelling ad experiences that consumers won’t want to block.”

Desktop and laptop computers are more likely to have ad blocking software installed than smartphones, although there is some overlap among users. eMarketer predicts that 63.2 million people will use one on their PC this year, and 20.7 million will use one on their smartphone. Ad blockers are expected to become more popular on smartphones, with eMarketer forecasting a 62.3-percent increase in mobile users this year.

“Ad blocking is more common on desktops and laptops because screen sizes are large enough to accommodate multiple ads. This includes videos that might be out of view but still audible, which are especially annoying to users,” says Verna. “Also, ad blockers typically don’t work on apps, where users spend most of their mobile internet time.”

Click here for more details on eMarketer’s findings.