Welch, L S, Sokas, R · Toxicology and industrial health · 1992
When workers were exposed to problems in a building (sick-building syndrome), some developed multiple chemical sensitivity (MCS)—a condition where people react to low levels of chemicals. This study looked at 20 people affected by the outbreak and found that most had existing health conditions like allergies or asthma that got worse. Importantly, having ME/CFS did not predict who would develop MCS, and many people had ongoing problems beyond just MCS after leaving the building.
This study is relevant to ME/CFS patients because it explores the relationship between environmental triggers (building exposures), pre-existing conditions, and post-illness outcomes. Understanding how sick buildings can precipitate overlapping conditions like MCS and asthma—and how ME/CFS patients may respond differently to such exposures—helps clarify the multifactorial nature of post-outbreak illness clusters.
This study does not establish that sick-building syndrome causes ME/CFS, nor does it prove that ME/CFS predisposes to or protects against MCS development. The small sample size (n=20, only 3 MCS cases) and incomplete case ascertainment limit generalizability. Correlation between building exposure and illness exacerbation does not establish causation in individual cases.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Welch, L S & Sokas, R (1992). Development of multiple chemical sensitivity after an outbreak of sick-building syndrome.. Toxicology and industrial health. https://pubmed.ncbi.nlm.nih.gov/1412493/
BibTeX
@article{mecfsatlas-welch-1992-development-multiple,
author = {Welch, L S and Sokas, R},
title = {Development of multiple chemical sensitivity after an outbreak of sick-building syndrome.},
journal = {Toxicology and industrial health},
year = {1992},
note = {PubMed: 1412493},
url = {https://www.mecfsatlas.com/evidence/welch-1992-development-multiple},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/welch-1992-development-multiple
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