In the post-vaccine, post-Delta era of the pandemic, the music industry seems to be landing on a basic requirement for concert attendance: You must be fully vaccinated (as AEG is insisting upon beginning Oct. 1) or, barring proof of vaccination, provide negative test results (as is Live Nation‘s current policy). Los Angeles County has decided on a stricter standard.

As the New York Times reports, starting at 11:59 p.m. this Thursday, Los Angeles County will require masks at outdoor events that attract 10,000 or more people — which the county is referring to as “mega events.” This would include concerts at the Hollywood Bowl and performances of the LA Phil. The rule will apply to all people regardless of vaccination status. The county has been averaging 3,361 new cases a day, which the NYT says is an 18% increase over two weeks ago.

As opponents of this policy might point out, last week Chicago officials indicated that there was “no evidence” that Lollapalooza, one of the first major outdoor festivals to be held under the current public health conditions, was a super-spreader event. At the time the fest had yielded about 200 cases of COVID-19 out of about 385,000 attendees. However, LA County has tended to be more aggressive in its COVID containment measures, including a full-scale indoor mask requirement instituted last month.