[NOTE: This question relates 6 NYCRR Part 351, which implements the requirements of Titles 27 and 28 of Article 27 of the Environmental Conservation Law, aka "the plastic bag ban" which went into effect March 1, 2020, but was suspended for a variety of reasons until October 19, 2020. For more information on that, see the graphic at the bottom of this answer.]
Does the NYS plastic ban law apply to libraries using plastic bags for curbside pickup?
We purchased plastic bags to hold library items that patrons request, label the outside with their name and leave the bags on pick up carts in the foyer of the building. This is for patron privacy-others cannot see what a patron has requested. As well as a COVID-19 measure-others are not touching items for pick up to search for their materials.
We are tax-exempt and not selling anything. When our supply is exhausted I will explore other possibilities in order to support less plastic waste, even if the ban does not apply to us. But in the meantime, are we in violation of the plastic bag ban if we continue to distribute materials in plastic bags?
The answer for this member is: NO.
The NYS plastic bag ban does NOT apply to libraries using plastic bags for storage of items pending curbside pick-up, unless the libraries are required to collect sales tax.
So while this member's library can choose to phase out plastic bags, since it is not required to collect sales tax ("we're not selling anything"), it is not compelled to do so.
Here is what the new regulations prohibit:
351-2.1 Prohibitions. A person required to collect tax shall not:
(a) distribute any plastic carryout bag to its customers unless the bag is an exempt bag;
... [emphasis added]
"A person required to collect tax" (as if the term really needs clarification!) is defined as:
(l) ‘Person required to collect tax’ means any vendor of tangible personal property required to collect New York State sales tax pursuant to subdivision (a) of Section 1105 of the New York State Tax Law, “Imposition of sales tax.”
The trick is that the application of the law is not based on the taxability of the sale, but rather, the status of the bag distributor as a "person" required to collect tax.
This is further borne out by commentary from the NY Department of Environmental Conservation, which states:
As of March 1, 2020, all plastic carryout bags (other than an exempt bag) became banned from distribution by anyone required to collect New York State sales tax. For sales that are tax exempt, plastic carry out bags are still not allowed to be distributed by anyone required to collect New York State sales tax (unless it is an exempt bag). [emphasis added]
So, while the vendors at your library's annual craft fair (if you're able to have a craft fair, sigh), who have to collect sales tax, can no longer use plastic bags, a non-sales tax-collecting library's curbside delivery service can.
At "Ask the Lawyer," we are not used to being the bearers of good news. So just to be sure—I mean really, really sure—that we could give the above answer, I also checked the " REVISED REGULATORY FLEXIBILITY ANALYSIS FOR SMALL BUSINESSES AND LOCAL GOVERNMENTS" found on the NY Department of Environmental Conservation's web page at https://www.dec.ny.gov/docs/materials_minerals_pdf/part351rfafinal.pdf.
The "ANALYSIS" is one of the documents that drills a little more into the law, and how it will impact those it covers. It states:
In 2019, a new Title 28, “Bag Waste Reduction” was added to Article 27 of the ECL. This law bans the distribution of plastic carryout bags to customers, effective March 1, 2020, by any person required to collect tax. (“Person required to collect tax” means any vendor of tangible personal property subject to the tax imposed by New York State Tax Law section 1105(a), “Imposition of sales tax.”)
So, really: unless your library is collecting sales tax (for sales of food, or sales of items like t-shirts, office supplies, or other retail), these new requirements do not apply. But if your institution is registered to collect sales tax (for anything): beware, and "ban the bag."
Thank you for a great and timely question.
 Which, as the member states, they intend to do.
 On https://www.dec.ny.gov/chemical/50034.html, as of 10/21/2020.
 Yes, not-for-profit and education corporations that sell retail items have to collect sales tax (they don't have to pay it, but they have to collect it). For more info on that, see https://www.tax.ny.gov/pdf/publications/sales/pub750.pdf.