Associations Between Indoor CO₂ Concentrations and Sick Building Syndrome Symptoms in U.S. Office Buildings: An Analysis of the 1994-1996 BASE Study Data

TLDR

Higher indoor concentrations of air pollutants, driven by lower ventilation rates, are a potential cause of sick building syndrome symptoms in office workers, and indoor CO₂ concentration serves as a surrogate for other occupant‑generated pollutants and ventilation rate per occupant. The study used multivariate logistic regression to assess the relationship between indoor CO₂ levels and sick building syndrome symptoms among occupants of 41 U.S. office buildings. Two CO₂ metrics—average workday indoor minus outdoor CO₂ (dCO₂, 6–418 ppm) and maximum 1‑hour moving‑average indoor minus outdoor CO₂ (dCO₂MAX)—were constructed, and MLR analyses quantified their associations with SBS symptoms while adjusting for personal and environmental factors.

Abstract

Higher indoor concentrations of air pollutants due, in part, to lower ventilation rates are a potential cause of sick building syndrome (SBS) symptoms in office workers. The indoor carbon dioxide (CO2) concentration is an approximate surrogate for indoor concentrations of other occupant-generated pollutants and for ventilation rate per occupant. Using multivariate logistic regression (MLR) analyses, we evaluated the relationship between indoor CO2 concentrations and SBS symptoms in occupants from a probability sample of 41 U.S. office buildings. Two CO2 metrics were constructed: average workday indoor minus average outdoor CO2 (dCO2, range 6-418 ppm), and maximum indoor 1-h moving average CO2 minus outdoor CO2 concentrations (dCO2MAX). MLR analyses quantified dCO2/SBS symptom associations, adjusting for personal and environmental factors. A dose-response relationship (p < 0.05) with odds ratios per 100 ppm dCO2 ranging from 1.2 to 1.5 for sore throat, nose/sinus, tight chest, and wheezing was observed. The dCO2MAX/SBS regression results were similar.