PM2.5 Concentration and Composition in Subway Systems in the Northeastern United States

Abstract

The goals of this study were to assess the air quality in subway systems in the northeastern United States and estimate the health risks for transit workers and commuters. METHODS: We report real-time and gravimetric PM 2:5 concentrations and particle composition from area samples collected in the subways of Philadelphia, Pennsylvania; Boston, Massachusetts; New York City, New York/New Jersey (NYC/NJ); and Washington, District of Columbia. A total of 71 stations across 12 transit lines were monitored during morning and evening rush hours. RESULTS: We observed variable and high PM 2:5 concentrations for on-train and on-platform measurements during morning (from 0600 hours to 1000 hours) and evening (from 1500 hours to 1900 hours) rush hour across cities.

Systematic experimental comparison of particle filtration efficiency test methods for commercial respirators and face masks

“…For example, 8 h of respirator usage in an extremely polluted urban environment results in a mass loading of < 5 mg for the upper-limit at-rest breathing rate (20 VLPM) given above. This value was calculated assuming 500 μg PM m −3 , representing an extreme air pollution event (< 1 km visibility) in Shanghai, China 55 or an extremely dirty subway system 56 , 57 . Conversely, a respirator would need to be reused on 42 shifts of 8 h duration before reaching the 200 mg limit.…”

Underground railway particulate matter and susceptibility to pneumococcal infection

“… 4 Second, few epidemiological studies have focussed on the health effects of underground railway PM. Assuming a similar toxicity to outdoor PM 2.5 , Luglio and colleagues 2 estimated that subway commuters exposed to subway PM 2.5 have 11% increased risk of cardiovascular death. By contrast, a recent systemic review of studies of underground railway workers, concluded that there was little or no association of either disease or biomarker endpoints, albeit small sample sizes meant that it was difficult to draw robust conclusions.…”

“…5 Smith and colleagues 4 reported that LU-PM 2.5 comprises of 47% iron oxide,14% other metallic and mineral oxides, 11% organic carbon, and 7% elemental carbon with 21% of the unidentified mass likely to be silicates. Similarly, Luglio and colleagues 2 reported that iron and total carbon comprised 80% of US subway PM 2.5 mass. Thus compared with traffic-derived inhalable PM, underground PM has a much greater contribution from iron, principally iron oxide.…”

“…Concentrations of inhalable particulate matter (PM either less than 10 or 2.5 microns in aerodynamic diameter; PM 10 , PM 2.5 ) in underground railway systems with electric trains are frequently in excess of World Health Organization's limits, 1 and raises concerns about its potential to cause adverse health effects. For example, Luglio and colleagues 2 recently reported a mean real-time PM 2.5 concentration in the Port Authority Trans-Hudson subway (New York, US) of 779 µg/m 3 , including 1,700 µg/m 3 in one station. In Europe, Martins and colleagues 3 reported concentrations of PM 2.5 in platforms of the Barcelona (Spain) subway up to 91 µg/m 3 , and Smith and colleagues 4 reported a mean PM 2.5 in the London Underground (LU) of 88 µg/m 3 compared with overground traffic-related PM 2.5 of 22 µg/m 3 .…”

A Real-Time Comparison of Four Particulate Matter Size Fractions in the Personal Breathing Zone of Paris Subway Workers: A Six-Week Prospective Study

“…Because of this size distribution and a highly ferruginous composition, along with the presence of trace metals (Mg, Al, Si, Ti, V, Cr, Mn, Ni, Cu, Zn, Ba, and Pb) [ 23 , 24 ], subway PM generates more reactive oxygen species (ROS) and oxidative-stress-related outcomes compared to other PM [ 18 , 25 ]. A comprehensive assessment of individual exposure to subway PM, particularly the finest size fractions, is urgently warranted in order to identify the sources and factors that contribute to high PM levels in individual subway stations and lines [ 26 , 27 ]. While the potential health impacts of subway PM on workers and/or commuters remain uncertain, exposure assessment studies are essential for risk assessments and exposure control interventions.…”