Dozens of grocery store workers have died from the coronavirus, despite masks, temperature checks and capacity restrictions to keep them safe. So far, supermarkets have resisted the most draconian policy: banning customers from coming inside.

However, some worker experts, union leaders and small grocery owners believe it has become too dangerous to let customers browse aisles, coming into close range with workers. Grocery stores are still flooded with customers, and experts say it’s time for large chains to go “dark” to the public and convert to curbside pickup and home delivery for food and other essential goods.

“Careless customers” are “probably the biggest threat” to workers right now, according to Marc Perrone, president of the United Food and Commercial Workers’ union. The union said 85% of its grocery store member workers reported that customers are not practicing social distancing in stores.