In the case of an employee with a disability that prevents them from wearing a mask, the employer must provide a reasonable accommodation. What does reasonable accommodation look like? This could be having the employee work from home or significantly distanced from other employees. In the case of remote work, make sure that the employee can still perform all job requirements – otherwise, it’s not a reasonable accommodation. In some cases, an employer may deny a reasonable accommodation if it is an undue hardship or a direct threat. Undue hardship must be proved in litigation based on facts (such as disruption to business operations or financial hardships).
Please see our business guidance here https://jacohd.org/wp-content/uploads/2020/10/business-guidance.pdf.