Investigation into pedestrian exposure to near-vehicle exhaust emissions

Abstract

BackgroundInhalation of diesel particulate matter (DPM) is known to have a negative impact on human health. Consequently, there are regulations and standards that limit the maximum concentrations to which persons may be exposed and the maximum concentrations allowed in the ambient air. However, these standards consider steady exposure over large spatial and time scales. Due to the nature of many vehicle exhaust systems, pedestrians in close proximity to a vehicle's tailpipe may experience events where diesel particulate matter concentrations are high enough to cause acute health effects for brief periods of time.MethodsIn order to quantify these exposure events, instruments which measure specific exhaust constituent concentrations were placed near a roadway and connected to the mouth of a mannequin used as a pedestrian surrogate. By measuring concentrations at the mannequin's mouth during drive-by events with a late model diesel truck, a representative estimate of the exhaust constituent concentrations to which a pedestrian may be exposed was obtained. Typical breathing rates were then multiplied by the measured concentrations to determine the mass of pollutant inhaled.ResultsThe average concentration of diesel particulate matter measured over the duration of a single drive-by test often exceeded the low concentrations used in human clinical studies which are known to cause acute health effects. It was also observed that higher concentrations of diesel particulate matter were measured at the height of a stroller than were measured at the mouth of a mannequin.ConclusionDiesel particulate matter concentrations during drive-by incidents easily reach or exceed the low concentrations that can cause acute health effects for brief periods of time. For the case of a particularly well-tuned late-model year vehicle, the mass of particulate matter inhaled during a drive-by incident is small compared to the mass inhaled daily at ambient conditions. On a per breath basis, however, the mass of particulate matter inhaled is large compared to the mass inhaled at ambient conditions. Finally, it was determined that children, infants, or people breathing at heights similar to that of a passing vehicle's tailpipe may be exposed to higher concentrations of particulate matter than those breathing at higher locations, such as adults standing up.

Inhaled Diesel Emissions Generated with Cerium Oxide Nanoparticle Fuel Additive Induce Adverse Pulmonary and Systemic Effects

“…The mass concentrations of DE and DECe used in this study are several fold higher than ambient exposure levels. However, tailpipe emissions and near roadway levels of DE can reach mass concentrations in the hundreds of lg/m 3 PM (Buzzard et al, 2009). The low concentration of DECe used in our study is likely to occur near roadways and is more realistic for human exposure.…”

Causes and Consequences of Variability in Drug Transporter Activity in Pediatric Drug Therapy

“…Data are still sparse, and additional in vitro and in vivo studies are required to quantify pollutant‐transporter interplays. However, children may be particularly vulnerable to these potential deleterious effects of environment‐drug interaction, as exposure of small infants or infants in strollers to pollutant particles appears to be higher than in adults …”

“…However, children may be particularly vulnerable to these potential deleterious effects of environment-drug interaction, as exposure of small infants or infants in strollers to pollutant particles appears to be higher than in adults. 189,190…”

Diesel exhaust modulates ozone-induced lung function decrements in healthy human volunteers

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