Published: April 4th, 2013 at 11:53 am ET
WDSU, April 4, 2013: [...] ExxonMobil’s Chalmette Refinery reported releasing 10 pounds of benzene and 100 pounds of hydrogen sulfide early on Wednesday, but the La. Bucket Brigade said it released “far more.” [...] The Louisiana Bucket Brigade, a nonprofit environmental watchdog group, said the smell originated from the Exxon Chalmette Refinery and said that the Coast Guard confirmed it. [...] However, the DEQ hasn’t linked the smell to the Chalmette refinery. It is still investigating via air monitoring sites and field crews. [...]
NOLA: An odor identified as burning tires or oil that wafted over the New Orleans area may have been caused by a spill of wastewater at the ExxonMobil Chalmette Refinery, according to a report filed with the Coast Guard’s National Response Center and a second report issued by the National Ocean Service. The report to the response center by the refinery says that an unknown amount of waste water leaked onto the ground from the “Number 1 flare drum” at the refinery at 7:08 a.m. It did not say what chemicals, if any, were in the wastewater. [...]
Hydrogen sulfide is a highly toxic and flammable gas (flammable range: 4.3–46%). Being heavier than air, it tends to accumulate at the bottom of poorly ventilated spaces. Although very pungent at first, it quickly deadens the sense of smell, so potential victims may be unaware of its presence until it is too late. For safe handling procedures, a hydrogen sulfide material safety data sheet (MSDS) should be consulted.
Hydrogen sulfide is considered a broad-spectrum poison, meaning that it can poison several different systems in the body, although the nervous system is most affected. The toxicity of H2S is comparable with that of hydrogen cyanide. It forms a complex bond with iron in the mitochondrial cytochrome enzymes, thus preventing cellular respiration.
Since hydrogen sulfide occurs naturally in the body, the environment and the gut, enzymes exist in the body capable of detoxifying it by oxidation to (harmless) sulfate. Hence, low levels of hydrogen sulfide may be tolerated indefinitely.
At some threshold level, believed to average around 300–350 ppm, the oxidative enzymes become overwhelmed. Many personal safety gas detectors, such as those used by utility, sewage and petrochemical workers, are set to alarm at as low as 5 to 10 ppm and to go into high alarm at 15 ppm.
Additionally in Louisiana...