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Table 3 Incidence Rate Ratios (IRR) and 95% confidence intervals of acute respiratory symptoms (ARS) for each eruptive month(s) (reference = previous year’s same month(s)) for all health facilities and according to their distance from Nyiragongo. Values of n concern the numbers of health centres and values in italics indicate the IRR with significant p values for the comparison with the overall IRR

From: Respiratory health and eruptions of the Nyiragongo and Nyamulagira volcanoes in the Democratic Republic of Congo: a time-series analysis

EruptionDateIRR ≤ 26 km
(n = 17)
IRR > 102 km
(n = 21)
IRR overall
(n = 78)
Nyamulagira
2001, 6th Feb to 5th May
Jan - May 1999111
Dec 20001.8 [0.9–3.7]1.0 [0.6–1.7]1.4 [1.1–1.9]
Jan 20011.9 [1.0–3.5]0.9 [0.7–1.3]1.3 [1.0–1.6]
Feb - Apr 20011.4 [0.8–2.6]0.9 [0.6–1.2]1.2 [1.0–1.5]
May 20011.4 [0.7–2.8]0.8 [0.5–1.1]1.2 [1.0–1.5]
Nyiragongo
2002, 17th Jan
Nov 2000 - Feb 2001111
Nov 20011.3 [0.9–2.0]0.9 [0.5–1.4]1.3 [1.1–1.5]
Dec 20011.2 [0.8–1.8]1.0 [0.7–1.5]1.3 [1.1–1.5]
Jan 20024.9 [2.3-10.7]1.9 [1.2–3.3]2.1 [1.4–3.2]
Feb 20025.8 [2.4–13.9]2.1 [1.2–3.7]2.3 [1.5–3.6]
Nyamulagira
2002, July to Sept
May - Oct 2001111
May 20022.8 [1.4–5.4]2.1 [1.2–3.8]1.7 [1.3–2.2]
June 20021.6 [0.9–3.1]1.8 [1.0–3.2]1.4 [1.1–1.7]
July - Sept 20022.6 [0.9–7.2]1.5 [0.8–2.9]1.6 [1.2–2.3]
Oct 20021.8 [1.0–3.2]1.8 [1. 0–3.1]1.5 [1.2–1.8]
Nyamulagira
2006, 27th Nov to 5th Dec
Oct 2005 - Feb 2006111
Oct 20060.9 [0.7–1.1]1.4 [1.0–1.9]1.1 [0.9–1.3]
Nov 20061.1 [0.9–1.4]1.6 [1.1–2.4]1.3 [1.0–1.6]
Dec 20061.1 [0.9–1.5]1.4 [1.0–2.0]1.3 [1.0–1.7]
Jan 20072.1 [1.6–2.6]2.2 [1.4–3.3]1.8 [1.4–2.4]
Feb 20071.5 [1.0–2.2]1.9 [1.3–2.8]1.7 [1.3–2.1]
Nyamulagira
2010, 2nd to 27th Jan
Nov 2008 - Feb 2009111
Nov 20090.4 [0.2–0.7]0.8 [0.6–1.1]1.1 [0.8–1.5]
Dec 20090.3 [0.2–0.7]0.8 [0.6–1.0]0.9 [0.7–1.3]
Jan 20100.2 [0.1–0.3]0.8 [0.6–1.0]0.7 [0.6–1.1]
Feb 20100.3 [0.2–0.4]0.9 [0.7–1.3]0.7 [0.5–0.9]