Ash can cause wind health issues, especially for people who already are having problems. Ash can irritate eyes, throats, and lungs. The ash that would reach Naalehu would be quite fine and would be most noticeable on car windshields and house window sills.
If I start seeing ash, I'll most likely wear a dust mask while working outside today.
Oh by the way, did you know what Naalehu means? I've been told that it's old Hawaiian for "volcanic ashes". Good name!