A new Chinese study has found that wearing facemasks at home significantly reduces the risk of catching the coronavirus.

The study, published in the journal BMJ Global Health, interviewed 335 people in Beijing from late February to late March about their households during the ongoing pandemic. Researchers said each family had at least one confirmed case of COVID-19, with an average family of four people.

The researchers said most transmissions occurred from person to person within households and wearing facemasks in the same house was nearly 80 percent effective at reducing the transmission. However, it was found that wearing masks was not protective after the symptoms appeared.

In addition, using chlorine or ethanol-based disinfectant was 77 percent effective at reducing virus transmission.

“This study confirms the highest risk of household transmission being prior to symptom onset, but that precautionary [non-pharmaceutical interventions]

, such as mask use, disinfection and social distancing in households can prevent COVID-19 transmission during the pandemic,” the authors wrote.

In general, the study supports “universal face mask use, not just in public spaces, but also at home.”

Facemasks are becoming more accepted and sometimes required, in the United States. When the first case was reported in the United States, federal officials said facemasks were not necessary for those who were not sick.

However, as the number of cases grew, the Trump administration urged Americans to start wearing facemasks when they could not social distance.

American health experts have come out strong for facemasks in public, but not in the home.

Dr. Chris Murray of the University of Washington told CNN, “We now have really clear evidence that wearing masks works — it’s probably a 50% protection against transmission.”

Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases (NIAID), told CNN that wearing facemasks and washing hands “are the things that everybody should seriously consider doing.”

On Thursday, New York Governor Andrew Cuomo said he’ll sign an “executive order allowing private businesses to bar people who don’t wear face masks. The store owner has the right to protect himself.” Local government officials in Los Angeles told residents that facemasks were mandatory in mid-May when the stay-at-home orders were being eased, according to the Los Angeles Times.