If an employer opens the workplace, in line with public health orders, and a worker doesn’t feel safe to return, do they have to?

When an employer tells you you need to come back to work and you don’t feel comfortable working from the office, in general the employer doesn’t need to keep you. (But) California is ahead of the curve in terms of its laws. California labor code says that you have a right to refuse unsafe work, but the question of whether your generalized fears amount to unsafe work, that’s unlikely. There has to be some objective reason. If an employer said, “I don’t want you wearing masks” … that might give you grounds.