In many Southern California cities, diners are familiar with the placards adorning restaurant windows and doors reading A, B or C.

The letters denote the health grade that the county’s environmental health department has assigned to that site.

Giving letter grades is not mandated statewide. Some counties – Los Angeles, Kern and San Diego among the biggest – choose to give them out while others like Orange County and Sacramento County choose other programs.

Restaurants are not required to post placards. The only policy the state does require is for food operators to present consumers with inspection results if they are requested.

Still, many counties volunteer the information as a public service.

Kern County started using letter grades in 2007. Previous to this, there were some food sites there that struggled to maintain compliance with state food safety laws.

“This has provided another avenue to incentivize businesses to properly and safely prepare food,” says Matthew Constantine, Environmental Health Director of central California’s Kern County. “The public can now speak to where they spend their time and money.”

The letter grades are given after an inspection during which restaurants and other food sites are reviewed and points are deducted for infractions that vary by the degree to which they contribute to food borne illness.

A minor infraction might be a violation like slightly cracked floors. Major infractions include infestation of pests and lack of power and water.

An “A” grade means the deductions left the food site with 90 to 100 points and it has complied with state law. A “B” grade means the problems amounted to 10 to 20 points off.

Because each jurisdiction is not required to follow any statewide procedure, each county’s grading system may vary. While a “C” grade might usually mean 70 to 80 points, in Kern, the county has raised the bar to 75 points as the cut off for a “C” grade.

This means, major violations can come with a 26-point deduction and the automatic closure of the site.

Constantine admits that the inspection process isn’t perfect. There is the concern that the grade in the window doesn’t reflect the ongoing restaurant environment.

“If we’re there every four months, perhaps the inspection caught the restaurant on a good or bad day and it’s not representative of the normal status of the facility,” he says.

Also, grading may not be uniform because some inspectors give different inspections than others. To help check this, Kern allows food operators to contest their grades.

The details involved in providing letter grades like the contesting of scores is one reason why places like Orange County choose other systems. Orange County is the only jurisdiction in Southern California that does not use the letter grading system.

Instead, starting in October, the county plans to use placards, which in large font that can be seen from afar, tells diners whether the site passed or failed inspection.

Letter grading can cost the county more than a pass/ fail placard. Because food operators can contest “B” and “C” grades, often, these discussions can lengthen an inspection by four or five minutes.

Though it might not seem like a lot, inspectors go out to restaurants three times a year. Multiply that by the thousands of sites in the county, and the costs begin to accrue rapidly.

Richard Sanchez, Orange County’s director of environmental health, says another reason the county’s board of supervisors decided on the pass/ fail system was because there is no proven correlation between public health and posting placards.

Other systems include the color-coded postings used by Sacramento County. Green means the restaurant has passed inspection; yellow means a re-inspection is in order; and red means the site has failed inspection.

While programs vary, the main goal of all of these systems is consistent.

“We want to disclose information that the county collects so the public can make an informed decision and to provide a mechanism to recognize positive behavior and encourage others to follow,” Constantine says.