Cancer and air quality

March 9, 2008

Both the IN and PNJ have written about cancer this week. We wrote on a Baldwin County mother’s fight to have the state study high cancer rates in her community ( Cancer Concerns ). The PNJ has the air quality study conducted by Georgia Tech (Toxic hot spots ).

I’ve read the executive summary of the study. Here are the key findings – unedited by me:

Phase I: Assessing the Relative Risks Associated with Criteria and Air Toxic Pollutants in the Pensacola Area

* For this initial assessment of particulate matter, ozone, and air toxics in Escambia and Santa Rosa Counties, rudimentary analyses suggest that particulate matter likely presents the greatest risk to human health generally related to air quality in the Pensacola region. It should be recognized however, that there could be highly localized areas for which other pollutants could pose a greater risk.

Implications: Of the three classes of pollutants, ozone is the most well understood pollutant, though it may not pose the greatest health risk. Less is known about particle pollution and air toxics. In terms of allocating PAQS resources, the investigation’s ensuing primary focus (i.e. in Phases II and III) will be on PM, secondary on air toxics, and tertiary on ozone.

Phase II: Summer 2003 Pilot PERCH Air Quality Study
Key findings: Analyses showed sulfate was a large fraction of the observed ambient PM2.5 loading, with high concentrations most often associated with northerly flow. Additionally, organic carbon was likewise found also to be a large fraction of the ambient PM2.5 loading, with the highest secondary organic aerosol formation concurring with peak PM2.5 mass concentrations. Results from a separate study of volatile organic compounds showed that gasoline related sources are the dominate contributors to ambient gaseous VOC concentrations, suggesting that these same sources are significantly contributing to the organic aerosol fractions – both primary and secondary. Finally, a limited comparison of air toxic concentrations measured at the OJ Semmes Elementary School and air toxic concentrations estimated for the Pensacola area by the 1996 NATA, showed remarkable (perhaps fortuitous) agreement despite many differences in method, and temporal and spatial scales.

Implications: Coal and gasoline combustion were observed to account for most of the Pensacola atmosphere’s particle load during a high pollution event. Additional analyses (see Phase III) are needed to discern between local and regional sources, however.Implications:

Phase III: Comprehensive Air Quality and Air Toxics Modeling and Analyses

Key finding: although the effective contributions from satellite-detected ground fires could not be quantified, detailed analyses showed that they played an important role in the polluted event observed at the O. J. Semmes elementary school during the Phase II field study.

Implication: in addition to coal and gasoline combustion, open fires were also a noted source of particles during the observed pollution event.

Key findings: Consistent with observations in Phase II, sulfate constitutes half or more of the particulate load in the Pensacola area for a modeled 2001 pollution episode. Rather than local sources, however, sulfate concentrations were more sensitive to distant sources. In contrast, ammonium was more sensitive to local

Implications: like ozone, a combination of regional and local controls may be necessary to effectively manage particle pollution in the Pensacola area.

Key Findings: Three areas in Santa Rosa County and one area in Escambia County were estimated to have a possible elevated risk of cancer due to emissions from point sources (also called stationary or industrial sources). Only the Pace community in Santa Rosa County had a significant residential presence in close
proximity to the industrial source that is primarily accountable for the elevated risk. While of concern, the estimated risks are of a magnitude that is consistent with risks found near other industrial sources.

Implications: With some exception for residential areas very near or within the industrial zones identified as potential hotspots, analyses using RAIMI appear to suggest that toxic emissions from point sources are not a widespread source of cancer risk via the inhalation pathway in the Pensacola area (with the caveat that other pathways were not studied).

Key Findings: elevated cancer and non-cancer risks due to mobile sources are ubiquitous in the Pensacola area with higher risks generally along more highly traveled roadways. Arising from the emissions of formaldehyde, benzene, and butadiene from cars and trucks, risk diminishes by several orders of magnitude a
few hundred meters off the roadway.
Implications: residential and other populated areas immediately adjacent to busy roadways may incur significantly elevated cancer and non-cancer risks.

Key finding: though the emissions of HCl and HF from Plant Crist are sizable, they do not appear to present a significant acute health risk via inhalation.

Read more: paqs_executive_summary.pdf.

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