Face masks are no longer optional at essential businesses in the county's 2nd-largest city after a mandatory facial covering order went into effect in Chula Vista.

Chula Vista residents will be required to wear a covering over their face while at and outside essential businesses, the city said. The order did not go as far as to require face coverings while in other public areas but did "highly recommended to wear a face covering anytime outside of the home."

"The recommendation that if you leave your place, cover your face," Chula Vista Mayor Mary Salas said at a press conference where she was joined by other South Bay leaders. "In other words, you should wear a facial covering anytime you leave your home or encounter someone who is not in your household."

Chula Vista is mandating its residents wear facial coverings while out in public, a day after National city placed the order in effect.

Chula Vista leaders urged anyone over the age of two to wear a face covering while walking, exercising or walking the dog. Wearing a face covering doesn't eliminate the need for social distancing, the city said.

Businesses were already allowed to deny customers access if they were not wearing a face covering. Now, businesses will be allowed to report those that do not comply, Salas said.

Chula Vista Police Chief Roxanne Kennedy said the mandate will be enforced but warnings will be given first.

In less than a month, the department has received 460 complaints about locations or individuals who were not complying with the county's public health order. There have been 207 documented warnings, Kennedy said, and a second call would warrant a citation.

National City on Tuesday became the first city in the county to require citizens to wear face coverings while in public.

The rest of the county remains under the public health order guidelines, which does not require a face covering in public but strongly recommends that citizens wear one to prevent the spread of the novel coronavirus to their fellow citizens.

“Wearing a mask is an act of love," Salas said Thursday. "It's an act of love not only for yourself but for your family and your community. You're protecting yourself but your protecting your community as well."

Face coverings are now mandatory in National City and South Bay residents who spoke with NBC 7’s Audra Stafford said they agree with the measure.

Also in attendance at Thursday's press conference was National City Mayor Alejandra Sotelo-Solis, Imperial Beach Mayor Serge Dedina and San Diego City Councilmember Vivian Moreno, who represents the South Bay communities of Otay Mesa and San Ysidro.

While neither Imperial Beach or the city of San Diego has required face coverings in their jurisdictions, Dedina urged his residents to "rock them" and said that the South Bay is united in their efforts to confront the disease.

He later told NBC 7 that his city is looking into an ordinance that would require masks to be worn at essential businesses as well. Dedina said citizens want the new restrictions because too many people are showing up without face masks.

It is unclear exactly why the South Bay is disproportionately affected by COVID-19 but the proximity to the border and the large population of cross-border commuters and Ex-Pats who live in Tijuana but receive health care in the U.S. could be a reason, Salas said.

Salas and Sotelo-Solis presented other possibilities that could account for the higher COVID-19 rate in the South Bay, including a higher number of low-income people in certain pockets of their communities, residents with less access to health care, and a higher population of residents who work in essential roles, like at grocery stores or in hospitals.

As of April 14, San Diego County requires employees of some essential businesses (retail stores, gas stations, restaurants, pharmacies) to wear coverings, and strongly encourages citizens to wear them in public. Individual cities have the authority to issue orders that are, in some cases, more strict than the county's but not less strict, according to Supervisor Nathan Fletcher.