Relative risk of acute pharyngitis in communities exposed to vog from Kilauea Volcano, Hawai`i

Volcanic emissions are an emerging global health concern for the 600 million people who live near active volcanoes. The eruption at Kilauea Volcano has exposed Hawaiian populations to sulfurous volcanic air pollution called vog. Emissions of sulfur dioxide gas, routinely measured by the Hawaiian Volcano Observatory, averaged 2,034 tons per day during 2004-2006. This retrospective cohort study estimated the cumulative incidence of diagnosed acute pharyngitis in unexposed and exposed communities on the island over the 3-year period. Case records of clinic and emergency room visits by local residents were reviewed for evidence of clinical presentation and diagnostic accuracy of acute pharyngitis, streptococcal pharyngitis, and acute tonsillitis. The cumulative incidence rate was 102.06 per 1,000 in unexposed communities and 234.74 per 1,000 in exposed communities. Relative risk (RR) estimates were standardized for age and gender, revealing an elevated risk [RR = 2.30 (95% CI = 1.85-2.84)] for all pharyngitis diagnoses in the exposed communities. Most affected were children ≤14 years old. Smoking was more prevalent within the unexposed cases (31%) than exposed cases (16%). This study has demonstrated that communities continuously exposed to relatively low levels of vog have a higher risk of acute pharyngitis.