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Table 1 Study characteristics of studies with non-occupational populations

From: Respiratory health effects of exposure to low levels of airborne endotoxin – a systematic review

Non-occupational populations
Author (Year) Country Study designa Population Ageb Endotoxin assessment methods Exposure variables measured Spirometry Questionnaire Confounders accounted for
Asthma/COPD patient populations
Rabinovitch et al. (2005) US [45] CS 24 asthmatic school-children 8.8–9.0 (SD 1.0–1.1) -Personal and stationary sampling
-37 mm Teflon filter
- 2 L/min
-LAL assay
Airborne endotoxin, PM FEV1 Questionnaire on asthma severity
Delfino et al. (2015) US [46] L: follow up 10 days 43 asthmatic school-children 14.3 (range 9–18) -Personal sampling (10 days)
- 2.5 μm cyclone filter
-4 L/min
-LAL assay
PM2.5, endotoxin FEV1 and FeNO Reporting the use of asthma medication and symptoms every two waking hours Temperature, humidity
Lai et al. (2015) US [47] L: follow up 12 months 248 asthmatic school-children 8 (range 4–13) -Area air sampling with charged particle samplers (Quadra)
-LAL assay
Airborne endotoxin, settled dust and settled endotoxin FEV1 and FVC Questionnaire on respiratory symptoms and follow-up phone calls Age, sex, race, annual income, controller medication, home and school settled dust endotoxin and mouse allergen, season
Bose et al. (2016) US [62] L: follow up 6 months 84 COPD patients 68.9 (SD 7.4) -Area air sampling
-37-mm Teflon filters
-4 L/min
-LAL assay
Airborne and dust endotoxin, PM, second hand smoke, NO2 FEV1 Combination of MRC dyspnoea scale, modified ATS-DLD, and St. George’s Respiratory Questionnaire Age, gender, education, season of sampling, baseline pre-bronchodilator percent predicted FEV1
Other non-occupational populations
Schiffman et al. (2005) US [35] E: 1 h expo-sure 48 healthy subjects 26 (±9.46) - Air sampling
-Fiberglass filters
-46 L/min
-LAL assay
H2S, ammonia, total suspended particles, endotoxin and odour FVC, FEV1and FEF25–75% Environmental Exposures and Health Questionnaire Subjects were their own controls.
Hoopmann et al. (2006) Germany [37] CS 3867 children Range: 5–6 Individual exposure estimated with Lagrange dispersion model based on the emission of neighbouring livestock facilitiesc Airborne endotoxin, fungi, bacteria, total dust Questionnaire of the ISAAC studies for respiratory and allergic symptoms Atopic status parents
Horick et al. (2006) US [38] L: follow up 12 months 360 children range 2–3 months Airborne endotoxin levels were calculated from dust endotoxin levelsd Endotoxin, dust Monthly telephone calls during the first year of the child’s life Race, pets, total mass of dust collected, concrete floor, water damage and respiratory illness
Ramagopal et al. (2014) US [61] CS 75 children Range: 3–59 months Method 1: Stationary Indoor Monitors (SIM)
Method 2: PIPER (pre-toddler inhalable particulate environmental robotic)
PM, endotoxin ISAAC questionnaire Age, gender, family history of asthma, floor covering, pets
  1. aCS cross-sectional, L longitudinal, E experimental
  2. bAge (years): mean, presented as range if mean age is presented for subgroups only
  3. cEmissions used in the dispersion model were measured in the surroundings of stables. Meteorological data and data on the amount and type of animals were included in the model and exposures were assigned to participants’ address coordinates
  4. dA measurement error correction analysis was performed according to the regression calibration method. Initial measurements were endotoxin levels derived from living-room floor dust. Regression calibration was performed using 93 living-room airborne endotoxin measurements (polycarbonate filters, 2 L/min)