REDWOOD CITY (CBS SF) — Marking a shift in previous instructions, Bay Area health officials on Thursday started recommending residents cover their nose and mouth with cloth when leaving home for essential travel such as doctor appointments and grocery shopping.

The regional recommendation was made in alignment with new guidance from the California Department of Public Health.

COMPLETE COVERAGE: CORONAVIRUS PANDEMIC

The joint release by Bay Area health departments noted the face coverings do not have to be hospital grade but need to cover the nose and mouth. For example, bandanas, fabric masks and neck gaiters are acceptable.

Fabric covers and bandanas can be washed and used again.

The Office of the President asked a prestigious panel of scientists about the possibility the virus could be spread by conversation. The National Academies of Sciences responded that it seemed likely based on the available research.

“It summarizes the evidence that we have of aerosols of the coronavirus and the possibility of people not coughing and sneezing might, through their breathing alone, be capable of putting the virus into the air,” said UC Berkeley infectious disease expert Dr. Art Reingold.

One study collected air and surface samples from 11 hospital rooms where COVID-19 patients were undergoing treatment.

Researchers found the virus in the air, even though the patients were not coughing when the samples were collected.

“Obviously the advice now is that people in general when they’re out and about for shopping or going to the pharmacy should consider wearing a mask themselves, even if they’re not symptomatic,” said Reingold.

Earlier this week, Bay Area health officials extended the stay-at-home order that was already in place to May 3.

Health officials do not recommend that the public use medical masks (N-95 or surgical masks), which are in limited supply and must be preserved for our health care workers andfirst responders.

Previously, local officials were not recommending the large-scale use of face coverings, but circumstances have changed.

“In addition to shelter-in-place and social distancing requirements, wearing a mask in public is an important tool to stop the community spread of this disease,” said San Mateo County Health Officer Dr. Scott Morrow. “People with no visible symptoms or mild symptoms may have coronavirus and not know it. Wearing face coverings helps protect others from exposure.”

Health officials continue to stress that staying home, frequent hand washing and social distancing are the best ways to prevent the spread of COVID-19.

For updated information about coronavirus in the community, visit the Alameda, Contra Costa, Marin, Santa Clara, San Francisco, San Mateo county or Berkeley COVID-19 websites.