Mild exposure:

• Slight headache
• Vomiting
• Nausea
• Fatigue
• Blurred vision
• Flu-like symptoms that disappear when the person breathes fresh air

Medium exposure:

• Drowsiness
• Confusion
• Severe headache
• Rapid heart rate

Severe exposure:

• Convulsions
• Unconsciousness
• Cardiac/respiratory failure
• Even death

Severity of the physical symptoms will vary depending on age, general health, level of physical activity, and duration and concentration of exposure.