1. Microbial exposure of rural school children, as assessed by levels of N-acetyl-muramic acid in mattress dust, and its association with respiratory health 
Robert Theodoor van Strien, PhD, Regina Engel, MSc, Otto Holst, PhD, Albrecht Bufe, MD, Waltraud Eder, MD, Marco Waser, MSc, Charlotte Braun-Fahrländer, MD, Josef Riedler, MD, Dennis Nowak, MD, Erika von Mutius, MD, the ALEX Study Team 
Journal of Allergy and Clinical Immunology 
Volume 113, Issue 5, Pages (May 2004)
DOI: /j.jaci

2. Fig 1 Participation and consent in the ALEX Study.
Journal of Allergy and Clinical Immunology  , DOI: ( /j.jaci )

3. Fig 2
Correlation among muramic acid, dust, and endotoxin in mattress dust.
Journal of Allergy and Clinical Immunology  , DOI: ( /j.jaci )

4. Fig 3
Prevalence (in blue) and adjusted∗ odds ratios (in black) for wheezing (past 12 months) and asthma diagnosis with increasing† muramic acid concentration (ng/mg; ‡P < .10; §P < .05; ∥P < .01). ∗Adjusted for age, sex, study area, family history of asthma or hay fever, educational level of the parents, number of older siblings, living on a farm, and mattress dust endotoxin concentration. †Odds ratios compare children in the second ( ng/mg) and third tertile (>167.5 ng/mg) with children in the first tertile (<98.5 ng/mg) of the mattress dust muramic acid concentration.
Journal of Allergy and Clinical Immunology  , DOI: ( /j.jaci )