Fireworks that boom may lead to busts this Fourth of July.

Sales in unincorporated areas of the county began today ahead of the holiday. The county and a number of cities have enacted a wide range of rules regarding sales and use to curb fire, injury and waste.

Fireworks can be used on the holiday from 9 a.m. to midnight in unincorporated areas, according to a press release from Clark County. Last year, fireworks could be discharged as early as June 28 in certain areas.

“This update makes the allowable time for fireworks discharge consistent for all county residents in the unincorporated area,” Clark County Fire Marshal Jon Dunaway said.

People who use fireworks illegally, which includes curfew or device-type violations, are subject to a $500 fine for first-time offenders, and a $1,000 fine for subsequent infractions.

The county urges caution when disposing of fireworks, which contain heavy metals and other chemicals that can cause environmental damage by washing into storm drains. To avoid violating state and county littering laws, residents are advised to sweep up and dispose of firework debris after use and not light them near waterways.