Particle air pollution and its implications in the Pacific Islands

Emissions arising from diesel combustion and the open burning of wastes are of concern across the Pacific Islands. Using Suva, Fiji as a case study, particulate air quality was investigated from October 2014 to October 2015. Ambient particulate concentrations were determined for total, 10µm, 2.5 µm (PM2.5), 1 µm and ultrafine particle (<300 nm) size fractions at city, residential and background locations. Ion beam analysis, to determine elemental concentrations, focussed on the PM2.5 fraction, due to the strong evidence of adverse health impacts from PM2.5. Additionally, contemporary and fossil carbon percentages were determined. Sources of PM2.5 were quantified by emissions inventory as well as by statistical analysis of air sampling data. Mortality risk was determined using published risk data. Indoor PM2.5 concentrations and sources were also investigated. Ambient PM2.5 concentrations (mean one year) in Suva city were close to Australian standards (8 µg/m3). Residential area and indoor PM2.5 results demonstrated likely exceedance of these ambient standards. Emission inventory calculations showed diesel and waste burning to be large contributors to Suva’s airborne particulate, also reflected in elevated black carbon and ultrafine particle concentrations. Statistical analysis of elemental concentrations identified diesel combustion as a major contributor to Suva’s PM2.5 mass (21%), along with vehicle emissions (all fuel types 17%). Whilst waste burning (largely biomass) contributed only 8% to city PM2.5 mass, contemporary carbon concentrations indicated biomass burning contribution to airborne particulates in residential areas to be more than double compared to the city. Based on risk of black carbon exposure, mortality risk from diesel combustion in Suva (industrial, power generation and shipping) was estimated at 59 deaths per year; vehicle and open burning emissions also represented significant risk. Reduction of emissions from these three sources would improve air quality and reduce health risk. This applies for Suva and more broadly across the Pacific Islands region.