Federal experts from the CSB will investigate what happened before, during and after the ITC Deer Park fire that burned for three days.

The CSB, or Chemical Safety Board, is an independent federal agency charged with investigating industrial chemical accidents.

The ITC fire sent an ominous-looking plume of black smoke all the way to Waller County and caused a benzene scare Thursday morning in nearby communities. 

Deer Park and Galena Park were under shelter-in-place orders for several hours after air quality readings showed elevated levels of benzene.

The orders were lifted Thursday afternoon and residents were able to leave their homes. All roads closed during the shelter-in-place have reopened.

Some school districts are canceling classes again on Friday, as a precaution. Here's the list, which we will continue to update as necessary.

HISD precautions

HISD Superintendent Grenita F. Lathan, Ph.D. said Thursday that outside experts have been conducting random air-quality testing at schools on the east side. 

HISD Is providing extra nurses at those schools and has brought in an outside risk-management team.

All after-school activities were canceled at those schools, as a precaution.

Highlights from news conference with ITC and the EPA:

  • EPA spokesman Adam Adams said he doesn't expect the air quality issues to continue through the night. 
  • Adams said the EPA has an air quality bus testing the air up and down Hwy 225. The TAGA (trace atmospheric gas analyzer) has not had any significant hits for benzene or other chemicals. 
  • ITC believes the increase in benzene levels was caused by a shifting of the foam in one of the tanks, according to ITC spokeswoman Alice Richardson. 
  • When asked how much product is left in that tank, she said it's about half-full.
  • The spokeswoman, who broke down at one point during the news conference, said she can't give an exact timeline on how long the elevated levels of benzene will last.

10:20 a.m. Harris County Public Health tweeted: "We are diligently monitoring areas where elevated benzene levels were detected this AM. Fortunately, those levels are dropping substantially."

Rumor control: separating fact from fiction

Rumors about the fallout from the Deer Park fire continue to spread so we're sorting out what's true and what's bogus:

  • We can confirm there are NO evacuations anywhere in our region. 
  • The national guard has not been called in, but the 6th Civil Support Team from the Texas Military Department is supporting air monitoring operations.
  • Despite a report from the City of Pearland saying a wind shift would bring the "benzene plume" their way, the NWS said Pearland isn't expected to have any health effects connected to the Deer Park fire. Harris County Meteorologist Jeff Lindner agreed, adding there has been no wind shift. 

Do you have health concerns?

If you have health concerns connected to the ITC fire, you can call the "Ask a Nurse" hotline at 713-634-1110. 

Harris County Public Health will be providing free health services and wellness assessment to the community of Deer Park from 2 p.m. to 7 p.m. Thursday and Friday.  The mobile health clinic will be located at 500 W. 13th Street.

The event was planned before the ITC fire and is open to anyone. 

For anyone who is feeling stressed or anxious, the National Distress Hotline is available to help. 

That number is 1-800-985-5990.

The hotline is open 24 hours a day, 7 days a week for anyone in need of emotional support. 

Benzene exposure, signs and symptoms

Below are the signs and symptoms of benzene exposure.  They could present themselves anywhere from minutes to several hours after exposure”

  • Drowsiness
  • Dizziness
  • Rapid or irregular heartbeat
  • Headaches
  • Tremors
  • Confusion
  • Unconsciousness
  • Death (at very high levels)

Eating foods or drinking beverages containing high levels of benzene can cause the following symptoms within minutes to several hours:

  • Vomiting
  • Irritation of the stomach
  • Dizziness
  • Sleepiness
  • Convulsions
  • Rapid or irregular heartbeat
  • Death (at very high levels)

How to check air quality in your area

With news this morning that tests found higher than acceptable benzene in the air near the ITC plant, many of you are asking how to check those levels where you live or work.

Harris County has set up this special air quality page for the Deer Park fire. 

Here are some tips on how to use it.

How to shelter-in-place

When emergency management officials order a shelter-in-place due to hazardous materials possible in the air, these are steps you should take to seal off a safe space, according to FEMA.gov.

  •  Bring your family and pets inside.
  • Lock doors, close windows, air vents and fireplace dampers.
  • Turn off fans, air conditioning and forced air heating systems.
  • Take your emergency supply kit unless you have reason to believe it has been contaminated.
  • Go into an interior room with few windows, if possible.
  • Seal all windows, doors and air vents with 2-4 mil. thick plastic sheeting and duct tape. Consider measuring and cutting the sheeting in advance to save time.
  • Cut the plastic sheeting several inches wider than the openings and label each sheet.
  • Duct tape plastic at corners first and then tape down all edges.
  • Be prepared to improvise and use what you have on hand to seal gaps so that you create a barrier between yourself and any contamination.

RELATED: How to check air quality levels in your area

RELATED: City of Pasadena explains why there's no shelter-in-place there

RELATED: 'I'm ready to move' | Residents near chemical tank fire air out frustrations

RELATED: Deer Park neighbors finding ways to get back to normal after massive tank fire