Multiple Chemical Sensitivity (MCS)

August 09, 2017

Multiple Chemical Sensitivity (MCS)

Multiple Chemical Sensitivity (MCS) encompasses a wide range of symptoms which some people link to low-level chemical exposure in their environment. Symptoms people report include:

  • Headache
  • Fatigue
  • Dizziness
  • Nausea
  • Congestion
  • Sneezing
  • Breathing problems
  • Chest pain
  • Muscle aches
  • Skin irritation
  • Confusion
  • Trouble concentrating
  • Memory problems
  • Mood changes

The term “multiple chemical sensitivity” was coined in the 1980s, and since then, there has been much debate over the legitimacy of the condition. Currently, MCS is not recognized as a medical condition by the American Medical Association, although many individual medical professionals disagree.

Research on Multiple Chemical Sensitivity

A recent Australian study concluded that an estimated 2.9 percent of adults suffer from symptoms associated with MCS. The study also reported that 24.6 percent of adults report heightened sensitivity to chemical odors.

Using nuclear imaging technology and other advanced research techniques, Swedish researchers at the Karolinska Institute in Stockholm have identified several links between odors and MCS. Through their research, two specific processes have been found to cause individuals with MCS to react to chemical odors.

  1. Cognitive Brain Activity – The Swedish research showed that MCS patients process odors differently than individuals in a control group. Using nuclear imaging, it was discovered that odor-processing areas of the brain were activated less frequently in MCS patients. However, MCS patients showed an increase in activity in two different areas of the brain in response to exposure to odors.
  2. Serotonin and Harm Avoidance – The Karolinska Institute study also found that MCS patients exhibit higher levels of a measurable personality trait called “harm avoidance” than individuals who do not suffer from MCS. Also, MCS patients have reduced levels of 5-HT1A, a nervous system receptor that is activated by serotonin. A natural mood stabilizer, serotonin is associated with feelings of happiness and well-being. Researchers concluded that the deviations in the physiology of those suffering from MCS could make them more sensitive to environmental odors.

What Triggers Multiple Chemical Sensitivity


Substances that typically trigger symptoms in people with MCS are synthetic chemicals. Some of the most common offenders are:

  • Nail polish and nail polish remover
  • Synthetic fragrances
  • Tobacco smoke
  • Automobile exhaust fumes
  • Insecticides
  • Hair care products
  • Alcohol
  • Cleaning products
  • Paint fumes
  • Gasoline and other petroleum products

Simple Steps to Control Odors

Many medical and health experts suggest maintaining optimal indoor air quality for managing the symptoms of MCS. Here are a few easily implemented tips for controlling indoor chemical exposure.

  1. Remove the Source. First, identify the source of a chemical odor and then remove it. As an example, all gasoline products, as well as equipment that uses gasoline, should be kept outdoors.
  2. Provide Adequate Ventilation. Open windows and doors whenever possible to allow fresh outside air to circulate indoors. Turn on exhaust fans when necessary.
  3. Avoid Chemical Air Fresheners. Air freshener sprays and scented candles only cover up unwanted odors. They don’t remove them. Many of these contain substances that are toxic to all the inhabitants of a home, not just those who suffer from MCS. Always avoid using chemical fragrance sprays, scented candles or wax, or any other synthetic air fresheners.
  4. Use a High-Quality Air Purifier. Individuals who suffer from MCS can benefit from air purifiers that effectively filter chemicals from indoor air. Air purifiers or cleaners must control a variety of chemicals while not being a source of chemical contamination themselves. Those who suffer from MCS report having the most success using the Austin Air HealthMate HM400 air purifier to improve indoor air quality and reduce exposure to chemical triggers.


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