APEX, N.C. — The company that owns the Apex plant where Thursday's explosion and blaze took place has had incidents related to hazardous chemicals, both in North Carolina and another state. However, local officials said they were unaware of a state violation that resulted in a fine against the company in March.

Thursday's incident is not the first disaster to occur at an Environmental Quality facility. In August 2005, a blaze tore through an EQ plant outside Detroit. No one was hurt in the explosions and fire in Romulus, Mich., but hundreds of people were forced to leave their homes for more than a day while it burned out.

The company is trying to re-establish the plant that was destroyed, but Michigan officials told WRAL on Friday that the Apex fire has given them second thoughts.

The cause of the Apex fire is under investigation, but problems were found at the facility seven months ago, when the North Carolina Department of Environment and Natural Resources cited EQ and fined it $32,000.

Among the list of violations was a failure to maintain and operate the facility to "minimize the possibility of a sudden or non-sudden release" of hazardous waste. Also, the company was cited for failing to clearly mark containers to identify their contents and improper log books.

According to citation from NCDENR's Division of Waste Management, the violation was easy to fix, but the information was significant. The fine stemmed from a July 2005 incident in which a hazardous situation was ignored.

The NCDENR citation says EQ officials smelled ammonia when they were loading a tanker truck bound for South Carolina, but higher management was not notified. When it arrived in South Carolina, officials there noticed a drip and vapor, resulting in an emergency situation. After investigating the incident, officials determined chemicals from a previous load in the tanker reacted with barrels being loaded onto the truck.

State officials noted that hazardous waste companies in North Carolina are inspected four times a month. EQ had its latest state inspection last week.

While it's unclear what specific chemicals were inside at the time of the fire, North Carolina State University air quality professor Viney Aneja said the very nature of the business makes it dangerous. The site is permitted to transport and dispose of almost all materials considered hazardous.

According to its Web site, EQ offers airport services, hazardous waste disposal and waste treatment disposal. Aneja said the chemicals listed in the company's permit include industrial cleaners.

"Each in themselves is a very corrosive toxic substance," Aneja said.

Environmental Quality purchased the Apex site in 2003, according to Wake County tax records and company officials in Michigan. Prior to 2003, the company was called EQ Industrial and EnviroChem. The former company or companies were doing work similar to EQ, according to EQ officials.

EQ only had the one citation at the Apex site since it purchased the company. However, the facility's former owners were fined $131,000 in 2001, in part for improperly processing mercury.

The town of Apex and the Wake County Health Department said Friday they were never notified of the citation from March.

"I understand they were fined something in the neighborhood of $30,000," said Apex Mayor Keith Weatherly. "I found out from the media. We were never notified."

NCDENR officials said the department notified the health department, and they pointed to a letter sent after the March violation that was also copied to the Wake County health director.

Rick Rowe, Wake County's Director of Environmental Services, said the NCDENR letter could've ended up anywhere, but insisted he didn't get it. Rowe said he's previously asked the state to address letters to a specific person.