Controlling fumes generated during EEG electrode application and removal



Electroencephalography ― more commonly known as EEG ― is the process of detecting and recording electrical activity in the brain by applying electrodes along the scalp.

Mayo Clinic explains that our brain cells communicate via electrical impulses and are active all the time, even when we are sleeping. This activity shows up as wavy lines on an EEG recording.(1)

Both clinical and research professionals rely on EEG recordings to aid in the analysis of a patient’s brain activity. Depending on the reason for the EEG, the test duration could last anywhere from 20 minutes to multiple days.

Most clinical applications of EEG include diagnostic tests for epilepsy and other spells such as movement disorders, fainting and migraines; determining whether a patient can be weaned from anti-epileptic medications; monitoring patients in a coma and aiding in determining brain death.

Researchers in the neuroscience, cognitive science and related fields also utilize EEGs.

Preparing a patient for EEG

There are four basic steps for preparing a patient for EEG monitoring.

  • Step 1: Skin Preparation
    • The patient’s scalp must be free of dead skin cells, oils and other hair products in order for proper adhesion.
  • Step 2: Electrode Adhesion to Scalp10-20placement
    • A conductive paste, or collodion, covers the entire metal tip of the electrode for adhesion onto the scalp. Gauze or cotton balls are usually placed on top of the electrode to prevent the paste from drying out during the test.
  • Step 3: Electrode Gel Application
    • Once the electrode is firmly in place, a syringe-like tube can be used to insert the gel into the electrode.
  • Step 4: Electrode Removal
    • Once testing is complete, a generous amount of remover is applied to the electrode until it is gently removed.

While the use of EEG and its recordings help to better assess the patient, fumes from the gels and pastes used to apply the electrodes, pose respiratory hazards to both the patient and technician.

Acetone, Ether, harsh chemical fume

Upon review of multiple brand name EEG products, a variety of chemical ingredients where found:

  • 1,2-Propanediol
  • Acetone
  • Aluminum Oxide
  • Calcium Carbonate
  • Cellulose nitrate
  • Ethyl Ether
  • Gelwhite
  • Glycerin
  • Isopropanol
  • Methylparaben
  • Polyoxyethylene (20) Cetyl Ether
  • Polyoxyethylene (20) Sorbitol
  • Potassium Chloride
  • Propylparaben
  • Sodium Chloride
  • Sodium Polyacrylate

Acetone and Ethanol in particular release harmful, aromatic fumes that should be captured and filtered. The below chart outlines regulated exposure limits for both these chemicals and related symptoms of exposure.



Exposure Limit


Exposure Limit



TWA 250 ppm

(590 mg/m3)

Eye, skin, and respiratory irritation,

headache, dizziness, light-headedness, weakness, incoordination, sleepiness, narcosis.

No established RELs

Eye, skin, upper respiratory system irritation; cough, sore throat; dizziness, drowsiness; headache; narcosis; nausea, vomiting; labored breathing, unconsciousness; dry skin.


TWA 500 ppm

(1,188 mg/m3)

STEL 750 ppm
(1,782 mg/m3)

TWA 400 ppm

(1210 mg/m3)

STEL 500 ppm

(1520 mg/m3)

Portable, Light-weight Chemical Fume Extractor

Sentry Air Systems Medical Fume ExtractorSentry Air Systems Model 300 Medical Fume Extractor (SS-300-MED) is a compact, portable ductless system equipped with an energy-efficient fan and semi self-supportive flex arm that captures harmful chemical fume at the source of emission.

The unit does not require exterior venting and the locking casters allow the unit to move freely throughout a hospital or doctor’s office setting. A variety of filter media is available including an activated carbon granule filter for exceptional adsorption of chemical fume.(2) Specialty carbon blends are also available for specific chemical odor applications.

We posted a previous blog that discusses collodion adhesive fume in more detail, you can read it here.



(2) Sentry Air Systems demonstrates how their activated carbon filters work

Contact Sentry Air

For more information about chemical fume removal or to receive a free quote, contact Sentry Air at 800.799.4609, email, visit our website or fill out the feedback form below.