The Air Pollution Control District has approved a permit that would allow a company in Louisville’s Rubbertown neighborhood to stop using a hazardous chemical. The switch would substitute two other chemicals in the process.Neither cyclohexane nor methylcyclohexane are regulated under the city’s Strategic Toxic Air Reduction Program. American Synthetic Rubber was granted permission to begin using the chemicals in place of toluene, which is categorized as a hazardous substance and is regulated as such.The district held a public hearing last month, and American Synthetic Rubber testified the switch would be good for the environment, as well as for the company’s bottom line. But some Rubbertown residents expressed concern that there’s inadequate data about cyclohexane and methylcyclohexane.In its response to the comments from the public hearing, the district announced its intention to issue the permit. It stressed that the two new chemicals aren’t regulated as hazardous air pollutants—unlike toluene—and that studies have shown the chemicals aren’t carcinogenic.