A coworker was diagnosed with covid19.the building was deep cleaned.have been working remotely.need to be in the basement1 day for 1 hr to mail out bks.have heart problm&borderline hbp.when is it safe for me to come in the basement?it has no windows?

Likely ok: If that basement room was indeed deep cleaned & there is no alternative way for you to do this task (or to get someone lower risk to do it) & it only takes an hour, you could likely go ahead: wear a mask, wash hands frequently, take a fresh air break halfway through. Take Vitamin C, Vitamin D3, & zinc supplements if not already doing that.