CHARLESTON, W.Va. — More than 100 days after a chemical spill into 300,000 West Virginians' water source, federal officials are trying to determine at what level people can safely breathe the chemical's fumes.

Over the next few months, the Environmental Protection Agency will work on detecting the spilled chemical in air and creating a corresponding safety standard for inhaling it, said agency spokeswoman Liz Purchia. It's the first time federal officials will factor in precautions for more than just consuming the water, which was contaminated in a Jan. 9 spill.

EPA twice asked about making a standard for inhaling the chemical — once on the day after the spill, and again in early February. Both times, not enough information was available on the little-known substance, crude MCHM, Centers for Disease Control and Prevention spokeswoman Bernadette Burden said.

In the two weeks after the spill, people showed up at emergency rooms with ailments after drinking the chemical-tainted water. Patients also experienced health problems after bathing, showering and washing their hands with it. And they expressed concerns after breathing in the licorice chemical scent, such as when taking a shower.

State environmental regulators could use the new air monitoring method in a variety of settings: at the Freedom Industries spill site during cleanup; for odor complaints at homes or businesses near MCHM facilities; or at coal prep plants that use the coal-cleaning agent, said state Department of Environmental Protection spokeswoman Kelley Gillenwater.

"It could be used in the future to respond to any complaints about odors associated with this material," Gillenwater said.

Schools canceled classes in January and February after experiencing chemical odor problems, even while water samples came back safe according to CDC standards. The state asked EPA to craft the inhalation standard after students and school staff reported nausea and dizziness from the licorice chemical scent, Gillenwater said.

Gillenwater said she is not aware of recent odor complaints in taps at homes or businesses, where the smell lingered long after people were told to resume normal tap water use.

So far, CDC has provided the only other official spill-related health guidance. After a four- to 10-day ban on using tap water, people were told to flush the water lines in their homes and businesses and drink their water again based on the CDC mark. But the CDC only accounted for drinking the water.

Complaints of rashes and irritation at emergency rooms jumped Jan. 15, two days after officials told some citizens to start flushing their systems and use their water. Chemical levels in water at the regional treatment plant that day were 250 times lower than what CDC considered the maximum safe level.

CDC also only factored in a period of exposure lasting two weeks — not almost four months.

Until the regional water company changes all its filters by late May, researchers say the chemical will likely keep finding its way into the water distribution systems, albeit at levels thousands of times weaker than what CDC deems safe.

Asking for action on the inhalation standard, Kanawha County health officer Dr. Rahul Gupta on Wednesday sent a letter Wednesday inviting EPA Administrator Gina McCarthy to visit West Virginia to discuss what's being done in the spill's aftermath.