Particulate matter and manganese exposures in Indianapolis, Indiana

Area of Science:

• Environmental Health Sciences
• Air Quality Monitoring
• Exposure Assessment

Background:

• Particulate matter (PM) and manganese (Mn) are significant air pollutants with potential health impacts.
• Previous studies have investigated PM and Mn exposure, but direct comparisons between cities with different emission profiles are valuable.
• Methylcyclopentadienyl manganese tricarbonyl (MMT) is a gasoline additive that can contribute to Mn in the air.

Purpose of the Study:

• To determine and compare the distribution of personal exposures to PM2.5 and Mn in Indianapolis, IN, and Toronto, ON.
• To assess the influence of indoor/outdoor sources and occupational factors on personal exposures.
• To compare the quality assurance of monitoring data between the two study locations.

Main Methods:

• Personal, indoor, and outdoor air sampling for PM2.5 and Mn was conducted over a 4-month period in Indianapolis.
• Survey instruments (household screener, questionnaire, time-activity questionnaire) were used to gather participant and activity information.
• Data quality was assessed through interlaboratory comparisons, blank analyses, and reproducibility checks, comparing results to a similar study in Toronto.

Main Results:

• Indianapolis exhibited higher median and 90th percentile personal PM2.5 exposures (23 and 85 µg/m³) compared to Toronto (19 and 63 µg/m³).
• Indoor PM2.5 levels in Indianapolis were more skewed towards the fine fraction compared to Toronto.
• Median personal Mn exposures in Indianapolis (2.8 ng/m³) were substantially lower than in Toronto (8.0 ng/m³), with occupational exposures identified as a key factor for high personal Mn levels.

Conclusions:

• Personal PM2.5 exposures were higher in Indianapolis than Toronto, potentially influenced by factors like smoking.
• Manganese exposures were significantly lower in Indianapolis compared to Toronto, suggesting reduced MMT use or other emission sources.
• High correlations were observed between personal exposures and indoor concentrations for both PM and Mn, indicating indoor environments are key exposure settings.