Except as otherwise provided in sections 624.20 to 624.25, it shall be unlawful for any person to offer for sale, expose for sale, sell at retail or wholesale, possess, advertise, use, or explode any fireworks. This section shall not be construed to prohibit the possession, use, or explosion of fireworks by an engineer licensed pursuant to sections 326.02 and 326.03 or a person under the engineer’s direct supervision when undertaking acoustical testing; or sales at wholesale to those persons holding valid permits for a fireworks display from a governmental subdivision of the state; or sales outside the state or sales to licensed professional engineers for acoustical testing purposes only.