NEW YORK (CBSNewYork) – New York City health officials now say people should cover their faces whenever they leave their homes to slow the spread of the coronavirus.

“I’ve come to a conclusion that it’s time to advise New Yorkers to do something different,” Mayor Bill de Blasio announced Thursday night. “I want to emphasize what I’m about to tell you is very very important, but it does not in any way change the basic guidance that you received now over many weeks.”

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“The reason for this guidance is because the studies are showing that some asymptomatic people some pre-symptomatic people appear to actually be transmitting this disease,” the mayor added. “We don’t have perfect evidence. It doesn’t conform with what the initial information showed us weeks ago, but it does seem to be more and more evident.”

“The reason this is being discussed is that some protection, when you add it up across millions of people, has an impact,” Dr. Sachin Nagrani, Heal medical director, told CBS2’s Charlie Cooper.

WATCH: NYC Health Officials Say New Yorkers Should Wear Face Covers 

The mayor stressed N95 and surgical masks should be reserved for health care workers on the frontlines of the fight. Instead, he suggested people use things like bandanas, scarves and other homemade options.

“What I recommend is that for these face coverings to be used for a day, and then you can handwash them in soap and water,” said Health Commissioner Dr. Oxiris Barbot. “The important thing is that they dry completely.”

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So how can you make your own face cover? At the very least, wear a scarf or bandana over your mouth and nose.

Some DIY masks require a needle and thread, but some are even simpler.

For parents looking to put coverings on young children, Nagrani says use a lighthearted approach.

“For younger children, making it a game, making it fun is probably the best approach rather than scaring them,” he said.

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If you’re wearing a face cover, it is important to put it on and take it off properly.

The World Health Organization says people should:

  • Wash your hands with alcohol-based hand rub or soap and water.
  • Cover your mouth and nose, making sure there are no gaps between your face and the mask.
  • Avoid touching the mask while using it. If you do, wash your hands with alcohol-based hand rub or soap and water.
  • Replace the mask with a new one as soon as it is damp, and do not re-use single-use masks.
  • Remove it from behind and discard it immediately in a closed bin. Then, wash your hands again with alcohol-based hand rub or soap and water.

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Even with face covers, health officials say practicing social distancing and washing your hands are still key.