Manganese exposures in Toronto during use of the gasoline additive, methylcyclopentadienyl manganese tricarbonyl

Abstract

A year -long population -weighted study of personal exposures to particulate matter ( PM 2.5 ) was conducted in Toronto while the manganese -containing additive, methylcyclopentadienyl manganese tricarbonyl ( MMT ) , was present in gasoline at an average level of 11.9 mg Mn / l, which was higher than the maximum of 8.3 mg Mn / l allowed in the U.S. In this study, 925 three -day personal samples of PM 2.5 ( air concentration of aerosol with an aerodynamic diameter of less than 2.5 m ) were collected, along with a record of participants' occupations, personal habits, surroundings, and activities during sampling. Stationary samples of PM 2.5 were collected indoors and outdoors at a subset of participants' homes over the same 3 -day periods. Three -day samples of PM 2.5 were also collected at fixed locations. Personal exposures to PM 2.5 were highly influenced by exposure to tobacco smoke, and were poorly correlated with outdoor levels ( Kendall's tau = 0.13 ) . The mean concentration of PM 2.5 in homes ( 21 g / m 3 ) was significantly higher than the mean outdoor level ( 15 g / m 3 ) . By contrast, the mean PM 2.5 Mn concentration ( air concentration of Mn in PM 2.5 ) was higher outdoors ( 9.7 ng / m 3 ) than indoors ( 5.5 ng / m 3 ) . Other than from tobacco smoke, there were no indications of significant indoor sources of PM 2.5 Mn in homes. The most important predictor of exposure to PM 2.5 was time spent in the subway, and a high level ( 428 ng / m 3 ) of PM 2.5 Mn was measured in the subway. The source of this Mn was hypothesized to be friction erosion of subway rails. Small, but statistically significant correlations were present between personal exposures to PM 2.5 Mn and several traffic -related variables ( time spent in transit, in a motor vehicle, near a roadway with traffic, and in a parking garage ) . However, in a stepwise regression that adjusted for weather and personal activities, time in a motor vehicle was the only traffic -related variable significantly associated with PM 2.5 Mn, and it was only the 10th most important personal activity variable in the final model. Concentrations of PM 2.5 Mn were higher at two fixed locations than outside of participants' homes, which were likely further from high traffic areas than the fixed sites. Likewise, outdoor and fixed site samples collected during periods that included weekend days contained lower air concentrations of Mn than samples collected during weekdays when traffic was heavier. On the other hand, the monthly average concentration of Mn in gasoline was negatively correlated with both outdoor and personal PM 2.5 Mn, which suggests that traffic -related sources of Mn other than MMT may be present. After omitting participants with exposure to Mn from certain identifiable non -MMT sources ( subway riders, metal workers and persons exposed to tobacco smoke ) , the average ( median ) personal exposure of the remaining 325 participants to PM 2.5 Mn was reduced from 14 ng / m 3 ( 8.5 ng / m 3 ) to 8.3 ng/m 3 ( 7.0 ng / m 3 ) . Potential sources of this r...

Particulate matter and manganese exposures in Indianapolis, Indiana

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Particle Emissions From Rail Traffic: A Literature Review

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Development of a Manganese Speciation Method for Atmospheric Aerosols in Biologically and Environmentally Relevant Fluids

“…Studies of atmospheric ambient aerosols in the United States, United Kingdom, and Canada have reported total manganese air concentrations in the range of <1 to 50 ng m −3 (Allen et al 2001;Crump 2000;Kidwell and Ondov 2004). Ambient atmospheric manganese can be attributed both natural (e.g., resuspended soil) and anthropogenic (e.g., welding, fungicides, batteries, and steel production) sources (Mergler and Baldwin 1997).…”