Airborne gram-negative bacteria and endotoxin in sick building syndrome. A study in Dutch governmental office buildings.

METHODS

During a survey of building-related symptoms among 1355 employees working in 19 governmental office buildings in the Netherlands, we measured physical and chemical factors, airborne microorganisms, and endotoxin. Mechanically ventilated buildings were grouped as "healthy" or "sick" based on symptom prevalence (mean symptom prevalence < 15% or > or = 15%). We compared physical, chemical, and microbiological characteristics between mechanically ventilated and naturally ventilated buildings.

RESULTS

Gram-negative rods were found in higher numbers in the "sick" buildings. The concentration of airborne endotoxin was six to seven times higher in the "sick" buildings than in the "healthy" buildings (254 vs 46 ng/m3); it was 35 ng/m3 in naturally ventilated buildings. No differences in physical characteristics of the buildings were found. Volatile organic compounds and carbon dioxide were present at higher concentrations in naturally ventilated buildings.

CONCLUSION

Airborne microbial contamination, in particular with gram-negative rods and perhaps with endotoxin, may have a role in the causation of sick building syndrome.