Particulate Matter Oxidative Potential from Waste Transfer Station Activity

Article excerpt

BACKGROUND: Adverse cardiorespiratory health is associated with exposure to ambient particulate matter (PM). The highest PM concentrations in London occur in proximity to waste transfer stations (WTS), sites that experience high numbers of dust-laden, heavy-duty diesel vehicles transporting industrial and household waste.

OBJECTIVE: Our goal was to quantify the contribution of WTS emissions to ambient PM mass concentrations and oxidative potential.

METHODS: PM with a diameter < 10 [micro]m ([PM.sub.10]) samples were collected daily close to a WTS. [PM.sub.10] mass concentrations measurements were source apportioned to estimate local versus background sources. PM oxidative potential was assessed using the extent of antioxidant depletion from a respiratory tract lining fluid model. Total trace metal and bioavailable iron concentration were measured to determine their contribution to PM oxidative potential.

RESULTS: Elevated diurnal [PM.sub.10] mass concentrations were observed on all days with WTS activity (Monday-Saturday). Variable PM oxidative potential, bioavailable iron, and total metal concentrations were observed on these days. The contribution of WTS emissions to PM at the sampling site, as predicted by microscale wind direction measurements, was correlated with ascorbate (r = 0.80; p = 0.030) and glutathione depletion (r = 0.76; p = 0.046). Increased PM oxidative potential was associated with aluminum, lead, and iron content.

CONCLUSIONS: PM arising from WTS activity has elevated trace metal concentrations and, as a consequence, increased oxidative potential. PM released by WTS activity should be considered a potential health risk to the nearby residential community.

KEY WORDS: antioxidants, iron, meteorology, oxidative potential, respiratory tract lining fluid, source apportionment, waste transfer sites. Environ Health Perspect 118:493-498 (2010). doi:10.1289/ehp.0901303 [Online 17 December 2009]

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Waste transfer stations (WTSs) represent a hybrid of traffic and industrial microenvironments. These sites experience high volumes of heavy-duty diesel trucks and are often situated in densely populated urban centers (Gil and Kellerman 1993). These facilities serve as the link in the waste management system between the waste collection program and final disposal: Street waste collection vehicles discharge loads, avoiding uneconomic travel to distant landfill sites. Although this approach effectively decreases the overall air quality burden the waste management system poses on an urban center, communities in proximity to WTSs suffer from enhanced traffic flow and increased particulate matter (PM) levels arising from vehicular tailpipe/nontailpipe emissions and dust releases from laden trucks (Fuller and Baker 2001; Restrepo et al. 2004). Studies conducted in New York City (Maciejczyk et al. 2004; Restrepo et al. 2004) and London (Fuller and Baker 2008) have reported that the highest PM concentrations in these urban centers occur at sampling sites influenced by WTS-related emissions.

Concerned citizens inhabiting urban communities with WTSs across the United States have raised questions to the WTS working group of the National Environmental Justice Advisory Committee about the impact of these facilities on the surrounding communities; degraded health and environmental conditions were highlighted as well as wider negative impacts on the community. The consequence of the environmental disamenities of these facilities has resulted in disproportionate clustering in low-income areas in the United States [National Environmental Justice Advisory Council) (NEJAC) 2000]. Similar studies in the United Kingdom have identified a disproportionately high number of industrial sites, including WTSs in socio-economically deprived regions (Higgs and Langford 2009; Walker et al. 2005).

The relationship between extended air pollutant exposure and increased prevalence of asthma symptoms has been well documented (Romieu et al. …