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Exposure to Toxic Components

Cleanup operations may expose workers to one or more of the following toxic components:

Nitrogen Dioxide (NO2)

The following are some components of nitrogen dioxide:

  • Gas with a distinctive reddish-brown color.
  • Possible exposure from combustible engine exhaust (i.e., diesel fumes) and controlled burning operations.

Nitrogen Dioxide Health Risks

  • respiratory irritant and is capable of causing pulmonary edema
  • a concentration of 50 ppm (parts per million) is moderately irritating to the eyes and nose and may cause pulmonary edema and possibly subacute or chronic lesions in the lungs
  • odor of NO2 is first perceptible to most people in the range of 0.11 to 0.22 ppm

Occupational Exposure Limits

Exposure limits regulated by OSHA and other agencies for NO2 range from 1-5 part-per-million (ppm) for a short 15 minute exposure period and 3-5 ppm average over a longer 8-hour exposure period.

NOTE: Workers should be informed that OELs based on standard times are not appropriate for monitoring. OELs do not include skin contact, absorption and ingestion which are common in cleanups.

Check with your site supervisor for additional guidance!

Sulfur Dioxide (SO2)

What is Sulfur Dioxide?

  • SO2 is released when burning crude oil and during degradation.
  • Sulfur dioxide emissions are also a precursor to acid rain and atmospheric particulates.

There are several health risks of Sulfur Dioxide. Here are a few:

  • Short-term exposures to SO2, ranging from 5 minutes to 24 hours, can cause adverse respiratory effects including bronchoconstriction and increased asthma symptoms.
  • When reacting with other compounds in the atmosphere to form small particles, they can penetrate deeply into sensitive parts of the lungs and can cause or worsen respiratory disease, such as emphysema and bronchitis, and can aggravate existing heart disease, leading to increased hospital admissions and premature death.

Occupational Exposure Limits

EPA set a 24-hour primary standard at 140 parts-per-billion (ppb) and an annual average standard at 30 ppb, and set a 3-hour average secondary standard at 500 ppb.

Carbon Dioxide (CO2)

What is Carbon Dioxide?

  • Carbon dioxide is colorless. At low concentrations, the gas is odorless. At higher concentrations it has a sharp, acidic odor.
  • Possible exposure can come from combustible engine exhaust (i.e. diesel fumes) and controlled burning operations.

Health Risks of Carbon Dioxide

  • CO2 is an asphyxiant and an irritant.
  • When inhaled, it can produce a sour taste in the mouth and a stinging sensation in the nose and throat.

Occupational Exposure Limits

Amounts above 5,000 ppm are considered very unhealthy, and those above about 50,000 ppm (equal to 5% by volume) are considered dangerous.

Carbon Monoxide (CO) Exposure

Carbon Monoxide has no warning properties; it is a colorless and odorless gas!

Carbon Monoxide may be present with:

  • any activity using gasoline, diesel or propane-powered machinery
  • work near operating equipment
  • debris reduction sites
  • work near hot work (cutting, welding) especially in confined spaces

Controlling Exposure

There are several things you can do to control exposure to carbon monoxide. Here are a few:

  • wear CO monitoring equipment
  • do not use gas/diesel powered equipment indoors or in enclosed areas
  • use forced air ventilation

Overexposure Symptoms

Symptoms include: Headache, dizziness, drowsiness, or nausea progressing to vomiting, loss of consciousness. Prolonged or high exposure can lead to coma or death. If you experience any of these symptoms where CO may be present: LEAVE THE AREA IMMEDIATELY.

Gasoline and Diesel Fuels

  • Gasoline or petrol is a petroleum-derived liquid mixture which is primarily used as a fuel in internal combustion engines. Diesel fuel is any liquid fuel used in diesel engines. These and other fuels will be used on the cleanup and can add to worker hazards.
  • Many of the non-aliphatic hydrocarbons naturally present in gasoline and diesel fuels are carcinogenic.
  • Brief inhalation of these and similar substances can also produce many of the effects of alcohol intoxication and, sometimes, a hallucinogen-like "trip."
  • Diesel combustion exhaust contains hazardous gases and particles which can be harmful if inhaled.

Diesel Combustion Exhaust

  • The largest components of most combustion gases is nitrogen (N2), water vapor (H2O), and carbon dioxide(CO2).
  • Relatively small components of it are noxious or toxic substances, such as carbon monoxide (CO), hydrocarbons, nitrogen oxides (NOx), Ozone(O3), partly unburnt fuel, and particulate matter.
  • Workers may be exposed to diesel combustion exhaust from working near diesel powered generators.

Hazardous Chemicals and Their Effects

Hazardous Chemicals Adverse Health Effects
Benzene (crude oils high in BTEX, benzene, toluene, ethylbenzene, and xylene) Irritation to eyes, skin, and respiratory system, dizziness, rapid heart rate, headaches, tremors, confusion, unconsciousness, anemia, cancer
Benzo(a)pyrene (a polycyclic aromatic hydrocarbon reproductive [see below], formed when oil or gasoline burns) Irritation to eyes and skin, cancer
Carbon dioxide (inerting atmosphere, byproduct of combustion) Dizziness, headaches, elevated blood pressure, rapid heart rate, loss of consciousness asphyxiation, coma
Carbon monoxide (byproduct of combustion) Irritation to eyes, skin, and respiratory, dizziness, confusion, headaches, nausea, weakness, loss of consciousness, asphyxiation, coma
Ethyl benzene (high in gasoline) Irritation to eyes, skin, and respiratory system, loss of consciousness, asphyxiation, nervous system effects
Hydrogen sulfide (oils high in sulfur, decaying plants and animals) Irritation to eyes, skin, and respiratory system, dizziness, drowsiness, cough, headaches, nervous system effects
Methyl tert-butyl ether (MTBE) (octane booster and clean air additive for gasoline, or pure MTBE) Irritation to eyes, skin, and respiratory system, headaches, nausea, dizziness, confusion, fatigue, weakness, nervous system, liver, and kidney
Polycyclic aromatic hydrocarbons (PAHs) (occur in crude oil, and formed during burning of oil) Irritation to eyes and skin, cancer, possible reproductive effects, immune system effects
Sulfuric acid (byproduct of combustion of sour petroleum product) Irritation to eyes, skin, teeth, and upper respiratory system, severe tissue burns, cancer
Toluene (high BTEX crude oils) Irritation to eyes, skin, respiratory system, fatigue, confusion, dizziness, headaches, memory loss, nausea, nervous system, liver, and kidney effects
Xylenes (high BTEX crude oils) Irritation to eyes, skin, respiratory system, dizziness, confusion, change in sense of balance, nervous system gastrointestinal system, liver, kidney, and blood effects



Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. EPA has set the 24-hour exposure limit for _____ at 140 parts-per-billion (ppb).

2. Which of the following can cause adverse respiratory effects including bronchoconstriction and increased asthma symptoms after a short exposure?

3. Irritation to the eyes, skin, etc., is a symptom of all of the listed hazardous chemicals, except _____.

4. What is the most common symptom of overexposure to a hazardous chemical during an oil spill?

5. Brief inhalation of these can produce many of the effects of alcohol intoxication and, sometimes, a hallucinogen-like "trip."

Have a great day!

Important! You will receive an "error" message unless all questions are answered.