Haw. Rev. Stat. § 132D-17.5: County ordinances.

(a) Nothing in this chapter shall be construed to supersede or in any manner affect a county fireworks ordinance; provided that the ordinance is at least as stringent in the control or prohibition of aerial devices, articles pyrotechnic, consumer fireworks, and display fireworks as the law under this chapter.

(b) Nothing in this chapter shall prohibit a county from enacting ordinances that are more stringent in the control or prohibition of aerial devices, articles pyrotechnic, consumer fireworks, and display fireworks than this chapter.