Oil Odors: If You Smell It, Is It Toxic?


Posted June 7, 2010 in Health and the Environment

Everywhere you go these days on the Gulf Coast, people are complaining about the smell of oil. Fishermen and other clean-up workers are noticing strong smells, and coastal residents from Venice, LA, to Pensacola, FL are complaining that when the wind is fairly still or when it blows from the South, they're suffering from the stench of oil. In some cases, people are telling us that when they smell the oil, they're feeling sick. Here's a comment that was posted on my blog this weekend:

"We live on the AL gulf coast - about 20-25 miles north of the gulf, and about 8 miles east of Mobile Bay. As I'm sure you're aware, the oil started washing up on shore here yesterday. Yesterday around 5pm (when the wind was still) I noticed the smell outside, which in my opinion was pretty strong, but later in the evening it seemed to vanish. I can still smell it slightly this afternoon, and as a mother, I'm naturally very concerned for my 4 year old daughter, husband & myself."

So the question everyone is asking is: If you can smell the oil, is it toxic?

The answer (unfortunately) is: "it depends".

There are lots of chemicals in crude oil and dispersants, and some are more toxic than others. Worse still, the health effects of some of the chemicals are untested and unknown. Some of the chemicals in oil are toxic at levels far below levels detectable by the human nose. For example, benzene is harmful at levels 1000-times below what people can smell. Other chemicals can be smelled at levels that are not considered harmful to health - an example of a chemical in that category is ethylbenzene. For other chemicals, the odor threshold is relatively close (within 10-fold) of the level that is considered a health concern. Some examples of chemicals in oil or dispersants, odor thresholds, and levels of health concern are in the table below.

The so-called volatile organic compounds (VOCs), tend to have a sweet-sour 'solvent' odor (think paint-thinner). The semivolatile compounds like naphthalene have an odor that's more like tar or creosote. Hydrogen sulfide gas has a characteristic 'rotten egg' odor. 2-butoxyethanol (a chemical in some of the dispersants) smells exactly like a household window cleaning product. So it's helpful to note the type of smell that you're experiencing, since it might provide a clue. I blogged about the health effects of some of these chemicals here.

The EPA has more information about odors from the oil on their website. Also, you can follow the results of the air monitoring on my blog (which I'm updating regularly), here for Louisiana. If you're from other Gulf Coast states, stay tuned to my blog site, since I'll start posting air quality updates for your state soon!

If you do notice odors, please report them to the Louisiana Bucket Brigade's Oil Spill Crisis Map, so they can track the problems and complaints. We're hoping that EPA will soon also have a place where people can report odor concerns.

So the bottom line is: if you smell it, it doesn't always means it's toxic (and if you don't smell it, that doesn't always mean it's safe), but for most of the chemicals in oil, the nose is a reasonable way of warning of the presence of oil vapors. Meanwhile, it's reasonable to take some common-sense steps if you notice strong odors. Going inside and turning the air conditioner on to recirculation mode for a while will reduce exposures to these chemicals. The levels in the air along the Gulf Coast are mostly looking OK for local residents so far, so any elevated levels of pollutants likely won't last very long (they are dependent on wind speed, wind direction, and temperature). So there's no need to leave the area or to hunker down indoors for the long-haul.

Workers offshore who notice strong odors or experience health symptoms should report them to their supervisor or the Coast Guard, and should get checked out by a doctor. I'm still not sure if it's safe to be working offshore without a respirator, so reports from workers are important so we know if there's a problem out there.


Odor Threshold (mean, ppm)

Odor Characteristic

NIOSH REL 8hr TWA (ppm)




Sweet, solvent














0.73 - 5.4






Tar/creosote, mothballs


0.0007 (Chronic)

Hydrogen sulfide

0.0005 – 0.3

Rotten eggs





Fruity/like glass cleaners



ppm = Parts per million

NIOSH = National Institute of Occupational Safety and Health

REL = Recommended Exposure Limit for workers

ATSDR = Agency for Toxic Substances and Disease Registry

MRL = Minimal Risk Level for community residents