Volcanic sulfur dioxide and acute respiratory symptoms on Miyakejima island.
OBJECTIVE
Following a volcanic eruption in 2000, high concentrations of ambient sulfur dioxide (SO2) are still observed on Miyakejima, Japan despite the reversal 2 years ago of the ban on residents living on the island. This study examines the association between current levels of volcanic SO2 and the incidence of acute subjective symptoms in volunteers on Miyakejima.


METHODS
The authors conducted a follow-up study on 611 healthy volunteers, on a person-hour basis (28 413 person-hours), who visited the island to provide support to residents from February to July 2005. Adverse health symptoms were measured by self-administered diary and exposure was approximated using monitoring data across 14 sites. Associations between incidence rates and increasing SO2 levels (reference (the lowest), very low, low, middle and high) were examined using Poisson regression.


RESULTS
Hourly incidence of cough, scratchy throat, sore throat and breathlessness showed clear exposure-response relationships with SO2 concentrations. There were statistically significant risks of those symptoms at relatively low SO2 levels. Thus, rate ratios in the 0.6-2.0 ppm exposure band (vs <0.01 ppm) were: for cough, 3.4 (95% CI 1.8 to 6.6) in men and 9.8 (3.9 to 24.9) in women; for sore throat, 3.2 (1.7 to 6.2) in men and 5.8 (2.0 to 16.5) in women; and for breathlessness, 10.5 (4.2 to 26.6) in men and 18.5 (4.6 to 74.3) in women. Little evidence of SO2 effects on sputum and nasal discharge/congestion was observed in this study. Eye and skin irritations showed inconsistent results between hourly maximal and hourly mean SO2 concentrations.


CONCLUSIONS
The authors observed strong evidence of an exposure-response relationship between volcanic SO2 and subjective acute respiratory symptoms among a healthy population on Miyakejima. The results are consistent with reports that females and non-smokers are more sensitive to irritant gas than males and smokers, respectively.
Ishigami
A
A
Public & Environmental Health Research Unit, London School of Hygiene & Tropical Medicine, Kappel Street, London WC1E7HT, UK. ai.milojevic@lshtm.ac.uk
Kikuchi
Y
Y
Iwasawa
S
S
Nishiwaki
Y
Y
Takebayashi
T
T
Tanaka
S
S
Omae
K
K
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000393:Air Pollutants / Q000032:analysis / Q000633:toxicity*; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis; D005260:Female; D017408:Guidelines as Topic; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012140:Respiratory Tract Diseases / Q000139:chemically induced* / Q000453:epidemiology; D013458:Sulfur Dioxide / Q000032:analysis / Q000633:toxicity*; D018707:Volcanic Eruptions / Q000009:adverse effects*; D055815:Young Adult
D000393:Air Pollutants; D013458:Sulfur Dioxide