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Boulder County now requires masks indoors — whether you’re vaccinated or not

The county is among the first few in the state that now require mandatory masking indoors for the general public since the statewide mandate was lifted earlier this year

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If you’re headed to Boulder County and plan to be indoors, don’t forget your mask.

Starting Friday at 5 p.m., masks are required in all indoor public spaces for everyone age 2 and older, regardless of vaccination status, according to a Boulder County Public Health order. 

Boulder County is among the first few counties in Colorado to reissue a mask mandate for the general public since Gov. Jared Polis eased the mask mandate earlier this year and as transmission rates rise due to the contagious delta variant. 


The health department will monitor transmission rates of COVID-19 within the county and require masks during periods of high and substantial transmission, based on levels defined by the Center for Disease Control and Prevention.

As of Friday, the CDC listed all but two of Colorado’s 64 counties as having either substantial or high transmission. Substantial transmission means a county has seen 50 new cases per every 100,000 people over the prior week or a test positivity rate over 8%. High transmission means a county has seen 100 news cases per every 100,000 people over the prior week or a test positivity rate over 10%.

Boulder, with 136 cases per 100,000 people over the prior week, is currently in the high transmission category, according to the CDC. Colorado as a whole is seeing a one-week case rate of 159 new cases per 100,000 people, according to the most recent CDC data. The percentage of tests coming back positive statewide during that period is just over 6%.

Boulder’s mask mandate will remain in effect for 21 days after moving into moderate or low transmission, according to the department. After 21 days in moderate or low transmission levels, masks will recommended, but not required, the department said. Masks indoors will become mandatory again if there is high or substantial transmission for five consecutive days. 

“Only second to vaccination, adoption of a universal mask order is an extremely effective tool to prevent the spread of COVID-19 and minimize disruptive cycles of reactionary orders, and is particularly important for seeing a rapid shift,” Camille Rodriguez, the health department’s executive director, said in a statement. “By adopting a universal mask order now, we can preserve our health care system resources, protect the health of our community, and prevent hugely impactful capacity and social distancing restrictions.” 

The health department is recommending the use of a surgical mask, N95 or KN95 when possible, though cloth masks that comply with the CDC mask guidance also meet the requirements of the health order. 

Boulder County’s latest mask mandate comes after the Center for Disease Control and Prevention issued an updated guidance on masking in late July, suggesting those who live in areas of substantial or high transmission to wear a mask in public indoor places, even if they are fully vaccinated. 

San Juan County implemented a similar mask mandate in early August and San Miguel County issued one Sept. 1.

CORRECTION: This story was updated at 3:42 p.m. on Friday, Sept. 3, 2021, to clarify that Boulder is among the first few counties to implement a mask mandate.

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