In conjunction with the Department of Agriculture, First Lady Michelle Obama announced a new proposal that would prohibit the marketing of specific products in public schools that fail to meet set nutritional criteria.

The proposal is part of the First Lady’s Let’s Move campaign and would track the criteria established by the Healthy, Hunger-Free Kids Act of 2010 and the USDA’s Smart Snacks in Schools program. Advertisements for junk food or soda would be eliminated from cafeterias and vending machines. The rule would also apply to in-school promotions, such as sponsored scoreboards.

“The idea here is simple – our classrooms should be healthy places where kids aren’t bombarded with ads for junk food,” the First Lady said in a statement. “Because when parents are working hard to teach their kids healthy habits at home, their work shouldn’t be undone by unhealthy messages at school.”

According to the proposal, the ban is necessary because research by the Federal Trade Commission revealed that more than 90 percent of the advertising found in schools is for soda, sports drinks, and other beverages.

Currently the Children’s Food and Beverage Advertising Initiative’s self-regulatory program places voluntary limits on food companies that advertise to children aged 12 and under. The proposal would apply to all food and beverage companies and extends to 18-year-olds in high school.

Industry reaction to the proposal was positive. Susan Neely, president and CEO of the American Beverage Association, told Ad Age it made “sense for the well-being of our school children,” and said her group looks forward to working with the USDA.

Similarly, the Grocery Manufacturers Association had only good things to say. “America’s food and beverage companies enthusiastically support the First Lady’s goal of solving childhood obesity within a generation, and are committed to providing consumers with the products, tools and information they need to build a healthy diet.”

To read the proposed rule, click here.

Why it matters: Some gray areas exist in the proposal, which is open for public comment until April 28. It applies only to advertising and marketing that occur during school hours and leaves uncertainty about night or weekend events held on school grounds. In some cases schools could make their own decisions about what constitutes marketing, such as how to handle a bake sale, but the USDA asked commenters to weigh in on how broadly “food marketing” should be defined. The agency also specifically sought feedback on another sticky area: sponsored events by companies, such as companies which work with schools to reward kids with food parties or coupons for reading a certain number of books.