Mystery odor from gas leak identified by Lubrizol as mercaptan: What officials are saying about the pungent-smelling gas

DEER PARK, Texas – Officials in La Porte issued an “all-clear” around midnight Sunday following reports of a mystery odor coming from Lubrizol Corp in Deer Park while the shelter-in-place order for Seabrook was lifted Monday morning.

The odor has been identified by Lubrizol Corp as a chemical called “mercaptan,” according to Deer Park Police Department on Monday morning.

What is mercaptan?

Mercaptan, also known as methanethiol, is an organic sulfur matter. The chemical is a pungent-smelling gas that has been described as having the stench of rotting cabbages or smelly socks, or what is commonly associated with the smell of natural gas since it is often added to natural gas to make it easier to detect.

What happened?

Emergency crews said the leak was reported around 8:15 p.m. at Lubrizol Corp, located at 41 Tidal Road in Deer Park.

All residents were asked to go inside and turn off the A/C system immediately, officials advised.

The La Porte Fire Department continued to detect an odor in certain areas of the city. Several residents in the areas were saying the odor was so strong, it was making them sick.

Initial reports from the facility stated that hydrogen sulfide was the chemical compound of concern, but pollution control later determined that hydrogen sulfide was not the primary chemical compound of interest.

According to a spokesperson for Lubrizol, the odor source resulted in a railcar being heated, and a pressure relief valve released the chemical causing odor. The railcar contained a zinc phosphate blend which decomposes to hydrogen sulfide. The stored material began to break down, resulting in an offsite odor release, the spokesperson said.

The spokesperson said materials causing the odor are widely used to odorize natural gas. Officials said air monitoring confirmed there remains no impact or risk to the surrounding community. The company said odors have largely dissipated, though some nuisance odors may still be present throughout the community.

Harris County Pollution Control was in the area to conduct air monitoring and to assist in the identification of the source of the odor. Deer Park Fire Department was also aware of the smell and had units monitoring the area.

Pollution control said it will continue to monitor air conditions in Deer Park and surrounding areas. Anyone with concerns related to the odor is being urged to call Harris County Pollution Control at (713) 920-2831.

Lubrizol released the following statement Sunday night:

“Tonight, an odor incident tied to a rail car vapor release occurred at our Tidal (Road) facility. Other than potential noticeable nuisance odors, there is no impact or risk to the surrounding community. We are actively working to resolve this matter, including working with local authorities to keep them advised. We apologize for any inconvenience.”

About Lubrizol Plant Facilities

Lubrizol Texas Facilities have been manufacturing highly specialized chemical products and services for a variety of applications in Deer Park since 1951, according to their website.

These include specialty additive systems for lubricating oils used in:

  • Gasoline and diesel engines
  • Automatic transmissions
  • Gear drives
  • Marine engines
  • Tractors
  • Metalworking

The company also supplies specialty products for industrial fluids, fuel additives, process chemicals and coating additives. Plant officials said the plant has over 600 workers.