Disposable Face Mask: Eligible Expense for FSAs or HSAs? flex spending, flexible spending account, flexible spending account buy online, fsa account, fsa expenses, fsa flex account What is a disposable face mask? Disposable face masks are loose fitting devices that create a physical barrier between the wearer's face and the breathable environment. They typically cover the wearer's mouth and nose to prevent inhalation of environmental particles that would negatively affect the wearer.