Studies of unexplained symptoms observed in chemically sensitive people have shown a relationship between neurological and immunological diseases caused by exposure to indoor air pollutants such as volatile organic compounds (VOCs). This article discusses the role of VOCs in neuroimmune interactions as well as the connection of exposure to low levels of chemicals with neurological dysfunction.

Sick building syndrome (SBS) and multiple chemical sensitivity (MCS) are suspected to be caused by inhalation of of VOCs. MCS patients have an increased susceptibility to immunological symptoms such as asthma, wheezing, and infections. The mechanism that triggers it are related to indoor air pollutants disrupting the regulation of nervous and immune systems and causing neurogenic inflammation. MCS is an amplification of the response to low-level irritants in the upper airways.

Formaldehyde is a toxic indoor air pollutant derived from furniture and construction materials. Exposure to it elicits a variety of allergic signs and symptoms, and irritates the upper respiratory tract. Animal studies of long-term exposure to low levels of FA show that it results in the induction of neurogenic and immunologic inflammation in the brain, which might trigger MCS.

The study found, that exposure to formaldehyde stimulated vagus nerve endings on mice to release neuropeptides that can activate immunological responses and modulate allergic inflammation. Chronic inflammation may in turn lead to changes in innervation patterns. Allergic reactions and exposure to formaldehyde acted in synergic manner on the brain statistically significantly more (p<0.05) in unexposed allergenic mice than on nonallergenic mice.