Elevated Airborne Exposures of Teenagers to Manganese, Chromium, and Iron from Steel Dust and New York City's Subway System

Abstract

There is increasing interest in potential health effects of airborne exposures to hazardous air pollutants at relatively low levels. This study focuses on sources, levels, and exposure pathways of manganese, chromium, and iron among inner-city high school students in New York City (NYC) and the contribution of subways. Samples of fine particulate matter (PM2.5) were collected during winter and summer over 48 h periods in a variety of settings including inside homes, outdoors, and personal samples (i.e., sampling packs carried by subjects). PM2.5 samples were also collected in the NYC subway system. For NYC, personal samples had significantly higher concentrations of iron, manganese, and chromium than did home indoor and ambient samples. The ratios and strong correlations between pairs of elements suggested steel dust as the source of these metals for a large subset of the personal samples. Time-activity data suggested NYC subways as a likely source of these elevated personal metals. In duplicate PM2.5 samples that integrated 8 h of underground subway exposure, iron, manganese, and chromium levels (>2 orders of magnitude above ambient levels) and their ratios were consistent with the elevated personal exposures. Steel dust in the NYC subway system was the dominant source of airborne exposures to iron, manganese, and chromium for many young people enrolled in this study, with the same results expected for other NYC subway riders who do not have occupational exposures to these metals. However, there are currently no known health effects at the exposure levels observed in this study.

Granulometric and magnetic properties of deposited particles in the Beijing subway and the implications for air quality management

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 13 PM collected at Beijing subway is found to have extremely high magnetic concentrations compared with the local street dust and surface soil samples (Table 3). This can be attributed to internal sources of iron-rich particles (Chillrud et al, 2004;Sitzmann et al, 1999). Suburban railway PM is also found to have high magnetic concentration; lower than particles from subway stations but much higher than naturally deposited particles.…”

“…As one of the most convenient public transportation systems for commuters, the Beijing subway has a passenger flow of ~10 million per day (www.bjsubway.com), the highest in the world. Due to the intrinsic nature of rail abrasion and train braking in the subway tunnels (Chillrud et al, 2004;Sitzmann et al, 1999), iron-containing particles can be generated and become suspended into the subway environment. Frictional abrasion contributes 40-73% of PM10s at the platforms in the Milan subway system in Italy (Colombi et al, 2013).…”

“…Previous attempts to assess the environmental conditions in the subway system have focused on the concentration and chemical composition of PM, with contradictory results (Aarnio et al, 2005;Boudia et al, 2006;Chillrud et al, 2004;Guo et al, 2014;Karlsson et al, 2005;Lu et al, 2015;Salma et al, 2007;Gómez-Perales et al, 2007;Querol et al, 2012) attributed to the different designs of the subway systems (Nieuwenhuijsen et al, 2007).…”

“…Iron-containing minerals were found enriched in the New York (Chillrud et al, 2004), Buenos Aires (Murruni et al, 2009) and Seoul subway systems (Kang et al, 2008). Studies have been made to monitor the in-train PM2.5 levels in the Beijing subway system (Li et al, 2006(Li et al, , 2007.…”

Particle Emissions From Rail Traffic: A Literature Review

“…Crump reported that time spent in Toronto subways was the best predictor of manganese in personal blood samples in his study (Crump, 2000). Chillrud et al (2004Chillrud et al ( , 2005 studied personal exposures to iron, manganese, and chromium dust among students and workers in New York City (NYC) and found that the NYC subway is the dominant source of these exposures.…”