Boston’s plastic bag ban begins today. Here’s what you need to know

Last year, Mayor Martin J. Walsh signed an ordinance banning single-use plastic bags in Boston, after the City Council unanimously approved the measure.

On Friday, Dec. 14, the new law took effect — and that means businesses will no longer be allowed to dole out those disposable shopping bags typically given to customers.

According to the Inspectional Services Department, enforcement of the new ordinance will be staggered and at first will only affect larger establishments that are more than 20,000 square feet.

In April 2019, the rules will apply to shops that are 10,000 square feet or more. Then, come summer, all stores citywide would need to comply with the rules.

In adopting the ban, Boston will join dozens of other communities across the state — and the country — hoping to do their part in cleaning up the environment.

“We know that single-use plastic bags have an impact on the environment. They often end up in city streets and gutters, abandoned lots, and even in trees,” according to a website set up by city officials to help explain the new rules. “Through this ordinance, the city aims to reduce the use of disposable checkout bags by retail stores in Boston.”

The city also hopes the ordinance will help reduce greenhouse gas emissions and solid waste, and protect marine wildlife, according to its website.

So, what happens when you stroll into a shop to buy something, just before the holidays? Here’s a quick breakdown of what customers can expect:

What kind of bag will I be getting when I shop?

The new rules stipulate that retail establishments will have to use alternate bags when packing up goods for customers. That means people will be going home with reusable bags, recycled paper bags, or compostable bags that they’ll have to purchase. Or, they can bring their own.

What about other smaller bags? Will those be eliminated, too?

Not according to the mayor’s office. As part of the ordinance, several types of bags are exempt from the new rules. Produce bags, bags used for dry-cleaning, newspaper bags, and bags used to wrap frozen foods will still be available. That means dog owners will still have some options when picking up dog waste.

Let’s say I go to a take-out restaurant — will they put my order in a plastic bag?

Nope. Sorry. According to the city’s website, “all bags at restaurants given to customers are subject to the guidelines in the ordinance. They have to be either recycled paper, compostable, or reusable.”

OK, so what’s the catch? Is this going to cost me money?

Pretty much.

Shoppers will have a few choices: They can bring their own reusable bags when out purchasing items, or they can pay a fee — no less than 5 cents per bag — for either a thicker, compostable plastic bag or a larger paper bag with handles.

Stores would collect the fees to help offset the cost of using the more expensive bags.

“Charges for checkout bags will appear separately on the receipt. To avoid being charged, customers can bring their own bags when shopping,” according to the ordinance.

I’m a business owner. This is going to be tough. Are there any exceptions?

Yes. While officials gave businesses a year to prepare for the changes, any business that feels like this will be a hardship can apply for a temporary exemption. Businesses only qualify if there’s no reasonable alternative to plastic bags; they can’t use up their remaining inventory in time; or “compliance with the ordinance would deprive you of a legally protected right.”

Retailers also aren’t required to provide bags at all and can rely on customers to bring their own.

Steve Annear can be reached at steve.annear@globe.com. Follow him on Twitter @steveannear. Globe correspondents Jeremy C. Fox and John Hilliard contributed to this report.