Background Endotoxin (LPS) released from gram-negative bacteria causes strong
immunologic and inflammatory effects and, when airborne, can contribute to respiratory
conditions, such as allergic asthma. Objectives We sought to identify the source of airborne
endotoxin and the effect of this endotoxin on allergic sensitization. Methods We determined
LPS levels in outdoor air on a daily basis for 4 consecutive years in Munich (Germany) and
Davos (Switzerland). Air was sampled as particulate matter (PM) greater than 10 μm (PM> …