Vinikoor et al. outcomes we examined. Therefore, we decided to conduct an additional analysis regarding ver- miculite insulation present in the house. All individuals were asked if vermiculite insula- tion was present in any of the Lincoln County addresses at which they reported living (Lincoln County includes Libby, Montana, and sur- rounding areas). Two hundred seventy-nine individuals reported vermiculite insulation pres- ent in the home, 633 reported no vermiculite insulation present, and 91 did not know (these 91 individuals were excluded from this further analysis). Controlling for age and sex, the OR for self-reported coughing up bloody phlegm in the past year comparing individuals with vermiculite insulation present in their house and individuals without vermiculite insulation was 1.58 (95% CI, 0.90–2.76). We also found no association for cough (OR = 1.12; 95% CI, 0.71–1.77), having shortness of breath (OR = 0.95; 95% CI, 0.62–1.45), or having lung disease (OR = 0.65; 95% CI, 0.33–1.30). The results were unchanged when adding personal smoking status and living/lived with a smoker to the model (data not shown). We conducted a sensitivity analysis by reclassifying the study participants with missing information on whether vermiculite insulation was present in their home. When all individuals with missing information were classified as having vermicu- lite insulation present in the house, the above results were essentially unchanged. The same was true when those with missing information were reclassified as living in homes without ver- miculite insulation. Finally, we examined the association between each of the activities as well as the variable for the combined activities with objective measurements from the spirometry testing (Table 3). We found no association between any of the exposure variables and an abnormal spirometry test result when adjust- ing for age, sex, personal smoking status, and living/lived with a smoker. The results were very similar when including only age and sex as covariates in the models (data not shown). We also performed an exploratory analysis to see if the association varied between obstruc- tive and restrictive spirometry results (data not shown). Because of small numbers, these CIs were very wide, making it difficult to dis- cern differences. However, it does not appear that the associations varied between the two types of abnormal results. Table 3. Age-, sex-, and tobacco-smoke exposure–adjusted associations between activities with possible exposure to asbestos-containing vermiculite and spirometry results among individuals ≤ 18 years of age when the mine closed in Libby, Montana. Association for all activities with potential for Libby amphibole exposure combined (no./frequency of activitiesd) Associations with individual activities with potential for Libby amphibole exposure Handled vermiculite insulation Participated in recreational activities along Rainy Creek Roade Played at the ball fields near the expansion plantc Played in or around the vermiculite piles Heated the vermiculite to make it expand/pop Exposure Never Sometimes 1–2 frequently ≥ 3 frequently Never Sometimes Frequently Never Sometimes Frequently Never Sometimes Frequently Never Sometimes Frequently Never Sometimes Frequently Never Sometimes Frequently 1036 Participated in other activities where contact was made with vermiculite insulation, products, or ores not mentioned aNumber of cases and controls do not always sum to total because of missing data on exposure. bSpirometry results were considered abnormal if they were classified as restrictive, obstructive, or mixed. cAdjusted for age, sex, smoking status, and living/lived with a smoker. d“Never“ means never participating in any of the activities; “Sometimes,” participating only sometimes in any of the activities; “1–2 frequently,” participating frequently in one or two of the activities; “≥ 3 frequently,” participating frequently in three or more of the activities. eRainy Creek Road is the road leading to the mine. Casesa,b (n = 94) Controlsa (n = 896) 8 41 39 6 74 14 5 40 38 15 24 35 35 65 17 10 71 18 5 68 22 1 97 361 384 52 655 196 38 385 374 128 234 301 357 642 171 68 666 184 42 678 180 28 ORc (95% CIc) 1.00 1.34 (0.60–2.96) 1.20 (0.53–2.70) 1.33 (0.42–4.19) 1.00 0.62 (0.34–1.12) 1.10 (0.42–2.91) 1.00 0.93 (0.58–1.49) 1.08 (0.56–2.08) 1.00 1.13 (0.65–1.97) 0.94 (0.54–1.65) 1.00 0.98 (0.56–1.73) 1.46 (0.70–3.05) 1.00 0.86 (0.49–1.51) 1.04 (0.39–2.79) 1.00 1.22 (0.73–2.04) 0.36 (0.05–2.69) Discussion This study has demonstrated a positive asso- ciation between certain activities resulting in exposure to asbestos-contaminated vermiculite and self-reported respiratory symptoms among individuals who were ≤ 18 years of age at the time of the mine closure in Libby. Frequent handling of vermiculite insulation was associ- ated with self-reported cough, shortness of breath when walking up a hill or hurrying on level ground, and coughing up bloody phlegm. However, in this study none of these outcomes were associated with simply living in a house with vermiculite insulation. Other exposures, such as frequently participating in recreational activities along Rainy Creek Road and frequently heating the vermiculite to make it expand/pop, were also associated with some adverse self-reported respiratory symptoms. The number/frequency of activi- ties had a positive trend with having a cough. Although the CI was wide when including smoking variables as covariates in the models, the trend with increasing frequency/number of activities remained. The number/frequency of activities was not associated with cough- ing up bloody phlegm or shortness of breath. None of the exposures were convincingly associated with self-report of having a lung disease or condition. However, because the individuals included in this study are young, it is possible that lung diseases or conditions did not yet have sufficient time to develop. Also, we found no associations between any of the exposures and abnormal spirometry results. Future studies will be important to follow this cohort and assess whether abnor- mal spirometry results and lung diseases do develop among this cohort of children. Overall, the rates of usually having a cough were higher among study participants than among the general U.S. population as represented by the NHANES data. Although these results are indicative of adverse respira- tory symptoms due to living in the Libby area, it is possible that factors other than exposure to asbestos-contaminated vermiculite contrib- uted to these elevated rates of cough. First, there is the discrepancy in definitions, with NHANES specifying that the cough was pres- ent for at least 3 consecutive months, whereas no time limitation was given in the ATSDR study. Second, because of the landscape of the area and the use of wood-burning stoves that occurred until recently in Libby, Montana, it is possible that the higher rates of cough in Libby can be attributed to higher levels of particulate matter in the air. Other stud- ies have demonstrated a positive relationship between levels of particulate matter and cough among children and adolescents (Epton et al. 2008; Pierse et al. 2006; Zhang et al. 2002). For the study years (2000 and 2001), the average annual levels of particulate matter ovlume 118 | number 7 | July 2010 • Environmental Health Perspectives