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Table 2 Demographic characteristics of the study population and daily number of individuals who were dispensed anti-asthma medication (AMD) or utilized health services for respiratory disease before and during the Holuhraun eruption

From: Severe volcanic SO2 exposure and respiratory morbidity in the Icelandic population – a register study

  Before eruption During eruption  
n % Events per day, mean (%) Range n % Events per day, mean (%) Range P*
Anti-asthma medication dispensings (AMD)
 All 45,473 100% 129.4 (100%) 5–715 11,094 100% 158.4 (100%) 22–301 < 0.001
 Female sex n, %) 25,608 56.3% 75.1 (41.8) 2–430 6552 59.1% 93.2 (45.7%) 13–185 < 0.001
 Under 18 years of age 14,144 31.1% 28.3 (21.9%) 0–139 2415 21.8% 33.2 (20.9%) 8–68 < 0.001
 18–64 years of age 24,117 53.0% 60.7 (46.9%) 3–386 5623 59.7% 75.2 (47.4%) 5–149 < 0.001
 65 years and older 7212 15.9% 40.4 (31.2%) 0–202 3056 27.5% 50.1 (31.6%) 0–105 < 0.001
Primary care center MD visits (PCMD)
 All 106,528 100% 142.2 (100%) 17–325 15,806 100% 144.8 (100%) 41–259 0.6531
 Female sex n, %) 59,429 55.7% 84.6 (59.5%) 9–180 9547 60.4% 87.9 (60.7%) 22–165 0.343
 Under 18 years of age 31,240 29.3% 39.2 (27.6%) 3–136 4140 26.2% 38.0 (26.3%) 13–75 0.4019
 18–64 years of age 64,840 60.9% 85.9 (60.4%) 12–191 9839 62.2% 89.7 (61.9%) 24–161 0.2951
 65 years and older 10,448 9.8% 17.1 (12.0%) 0–48 1827 11.6% 17.1 (11.8%) 0–42 0.9877
Hospital emergency department visits (HED)
 All 19,541 100% 18.3 (100%) 1–45 1932 100% 17.5 (100%) 4–34 0.176
 Female sex n, %) 9733 49.8% 9.2 (50.5%) 0–29 1000 51.8% 9.0 (51.6%) 2–18 0.527
 Under 18 years of age 6811 34.9% 5.7 (30.9%) 0–24 638 33.0% 9.0 (51.6) 0–16 0.640
 18–64 years of age 8258 42.3% 7.0 (38.2%) 0–24 758 39.2% 5.5 (31.6%) 1–14 0.269
 65 years and older 4472 22.9% 5.7 (31.0%) 0–19 536 27.7% 6.7 (38.0%) 0–13 0.198
  1. *from a t-test of means