Nassau County officials say the business in Plainview was selling the masks out of a warehouse on Old Country Road.
The business was fined $25,000.
"If you are buying this or using this, if you are a healthcare worker or a grocery store worker and you are depending on this for your health and your safety, you need to know that it is a legit product," said Laura Curran, Nassau County Executive.
The CDC and the World Health Organization say healthy people do not need to wear face masks.
They say they do not offer any health protection benefits.
MORE CORONAVIRUS COVID-19 COVERAGE
Frequently Asked Questions
Where are the testing centers
See how our communities are making a difference
Free educational resources for parents and children
How you can help victims of coronavirus
Where is COVID-19 now? and other resources
Coronavirus news and live updates in New York
Coronavirus news and live updates in New Jersey
Coronavirus news and live updates in Connecticut
New York City updates
Long Island updates
How coronavirus is leaving ghost towns in its path
Coronavirus prevention: how clean are your hands?
Social distancing: What is it and how does it stop the spread of coronavirus?
Coronavirus closures and cancelations
Coronavirus tips: What Americans need to know
Related Information
Centers for Disease Control and Prevention on coronavirus