Sprawl and Health

Riediker 2004 - "Particulate Matter Exposure in Cars is Associated with Cardiovascular Effects in Healthy Young Men"

Riediker, Michael; Cascio, Wayne; et al.
"Particulate Matter Exposure in Cars is Associated with Cardiovascular Effects in Healthy Young Men"
American Journal of Respiratory and Critical Care Medicine
April 15, 2004; v.168, n.8; pp.934-940
On the Web
Relevance: medium-low

Part of a larger research project measuring air quality in cars, the authors measured the effects of exposure to PM2.5 on the cardiovascular functions of nine young, healthy patrol officers in North Carolina. They concluded that in-vehicle PM2.5 negatively affected inflammation, coagulation, and cardiac rhythm in slight but significant amounts. However, they also measured PM2.5 concentrations to be lower in the vehicles than on the side of the road or at the ambient location.

This study suggests to me that even a small amount of PM2.5 from vehicles is bad.

Chang 2000 - "Hourly Personal Exposures to Fine Particles and Gaseous Pollutants--Results from Baltimore, Maryland"

Chang, Li-Te; Koutrakis, Petros; et al
"Hourly Personal Exposures to Fine Particles and Gaseous Pollutants--Results from Baltimore, Maryland"
Journal of the Air and Waste Management Association
July 2000; v.50, n.7; pp.1223-1235
On the Web
Relevance: medium

The authors measured personal VOC exposure in a variety of microenvironments that older adults generally encounter. PM 2.5 concentrations were highest in the food court, while walking and driving, and in a kitchen and TV room at home. Ozone levels were elevated while walking at noon and while driving. Carbon monoxide levels were elevated i the middle of the day and while driving.

Ambient concentrations of PM 2.5 seem to be fairly well with personal exposure (r>.6 for all but one case). Ambient concentrations of ozone were also highly correlated with personal exposure for outdoor and in-vehicle microenvironments, less so for indoor environments, and barely at all for homes. There seems to be little correlation between ambient BTEX levels and personal exposures in homes and cars (except for benzene in homes), which suggests to me that personal exposure in those places comes mostly from personal activities (cooking, cleaning, and driving).

Chan 1991 - "Commuter Exposure to VOCs in Boston, Massachusetts"

Chan, Chang-Chuan; Spengler, John D; et al.
"Commuter Exposure to VOCs in Boston, Massachusetts"
Journal of the Air and Waste Management Association
December 1991; v.41, n.12; pp.1594-1600
On the Web
Relevance: high

The authors measured VOC exposure for four commuting methods (car, subway, walking, biking) plus concentrations in homes, offices, and on the sidewalk in Boston. They found that concentrations were generally highest in cars and lowest in homes/offices. "For most VOCs, the concentrations in homes and offices were about three to five times lower than the VOC concentrations during commuting." Around 10-20% of daily VOC exposure for car and subway commuters occurred during the commute.

Driving on urban roads was correlated with higher VOC concentrations (1.5 times higher) than driving on interstates.  Using the heater also increased VOC levels. On the other hand, the age of the car or country of origin (US vs. imported) did not seem to make a difference.

Riediker 2003 - "Exposure to Particulate Matter, Volatile Organic Compounds, and Other Air Pollutants Inside Patrol Cars"

Riediker, Michael; Williams, Ronald; et al.
"Exposure to Particulate Matter, Volatile Organic Compounds, and Other Air Pollutants Inside Patrol Cars"
Environmental Science and Technology
2003; v.37 n.10; pp.2084-2093
On the Web
Relevance: high

The authors measured PM and VOCs in patrol cars, roadsides, and a remote (ambient) site in North Carolina. They found that BTEX levels were significantly higher in the cars; elemental carbon levels were higher in the cars; but NO2 and PM2.5 levels were a little higher in at the ambient site; and ozone levels were nearly twice as high at the ambient site.

Levy 2000 - "Particle Concentrations in Urban Microenvironments"

Levy, Jonathan I; Houseman, E. Andres; et al.
"Particle Concentrations in Urban Microenvironments"
Environmental Health Perspectives
November 2000; v.108, n.11; pp.1051-1057.
On the Web
Relevance: medium

The authors measured particulate matter indoors and outdoors in seven microenvironments (subway, bus, restaurant, hospital, gymnasium, museum, store) in Boston. Particle counts for PM 0.3-0.5 were generally higher inside the subway and bus than outdoors, but lower inside the store, hospital, and museum. Particle counts overall were higher inside the subway and bus than outside.

Leung 1998 - "Evaluation of Personal Exposure to Monoaromatic Hydrocarbons"

Leung, Pei-Ling; Harrison, Roy M
"Evaluation of Personal Exposure to Monoaromatic Hydrocarbons"
Occupational and Environmental Medicine
April 1998; v.55, n.4; pp. 249-257
On the Web
Relevance: high

The authors measured the exposure of 50 volunteers in the UK to various monoaromatic hydrocarbons (MAHs) over the course of 12 hour days. They found that urban volunteers were exposed to more MAHs than non-urban volunteers. Most of the total exposure is from the home, despite low concentrations, due to the vast amount of time spent there. Although little time is spent driving, the high concentration of MAHs in vehicles made it a noticeable contributor for office workers (5% of total exposure) 

Allen 2004 - "Estimated Hourly Personal Exposures to Ambient and Nonambient Particulate Matter Among Sensitive Populations in Seattle"

Allen, Ryan; Wallace, Lance; et al.
"Estimated Hourly Personal Exposures to Ambient and Nonambient Particulate Matter Among Sensitive Populations in Seattle"
Journal of Air and Waste Management
September 2004; v.54; n.9; pp.1197-1411
On the Web
Relevance: High

The authors measured the concentration of particulate matter in various mircoenvironments (home indoors, home outdoors, work, school, in transit, other outdoors, other indoors) and the average exposure for 38 subjects in Seattle. The subjects selected were "sensetive populations" with asthma, coronary heart disease, or advanced age. The major findings were:

• The best air was indoors at home; the worst air was at work, followed by outdoors and in transit.
• Because subjects spend so much time at home, most of their exposure (79%) occured there.
• There was a low correlation between ambient and personal exposures (0.43) compared to findings from other studies. This means that localized sources highly affect personal exposure (i.e. cooking fumes vs.general air quality)

Kingham 1998 - "Assessment of Exposure to Traffic-Related Fumes During the Journey to Work"

Kingham, Simon; Meaton, Julia; et al.
"Assessment of Exposure to Traffic-Related Fumes During the Journey to Work"
Transportation Research, Part D
July 1998; v.3, n.4; pp.271-274
On the Web
Relevance: medium-low

In a pilot study, the authors measured commuter's exposure to benzene and particulates using different modes (car, bus, train, road cyclist, path cyclist) but along similar routes(?). Findings include:

• The car driver had the highest mean exposure to benzene (108.3 micrograms/m^3) a factor of at least 4 and also the highest mean exposure to particulates (7.6 absorbance), but by a much smaller margin.
• Train riders had the lowest benzene exposure (12.9) and path cyclists had the lowest particulate exposure (2.7).
• The bus was slightly better than the road bike
• The exposure ratios for the car driver to the road cyclist were 4.05 for benzene and 1.26 for particulates.
• The exposure ratios for the road cyclist to the path cyclist were 1.73 for benzene and 2.41 for particulates.

Adams 2002 - "Assessment of Road Users' Elemental Carbon Personal Exposure Levels, London, UK"

Adams, HS; Nieuwenhuijsen, MJ; Colvile, RN.
"Assessment of Road Users' Elemental Carbon Personal Exposure Levels, London, UK"
Atmospheric Environment
November 2002; v.36, n.34; pp.5335-5342
On the Web
Relevance: low

The authors measured exposure to elemental carbon (EC) a component of diesel exhaust, along various routes, using different modes, and in summer vs. winter.  They found that exposure levels were higher:

• for cars, followed by buses and bicycles (cyclists may have lower exposure because they don't get stuck in traffic and keep "away from the central road 'tunnel of pollution'.";
• along the most congested central route, perhaps due to higher traffic density and a street canyon effect;
• in winter, perhaps due to colder engines and more stable meteorological conditions.

Fruin 2004 - "Black Carbon Concentrations in California Vehicles and Estimation of In-Vehicle Diesel Exhaust Particulate Matter Exposures"

Fruin, Scott A; Winer, Arthur M; Rodes, Charles E.
"Black Carbon Concentrations in California Vehicles and Estimation of In-Vehicle Diesel Exhaust Particulate Matter Exposures"
Atmospheric Environment
August 2004; v.38, n.25; pp.4123-4133
On the Web
Relevance: low

The authors measured black carbon (BC) concentrations inside vehicles driven around LA and Sacramento. BC is typically associated with diesel emissions. The authors found that the most important predictor of in-vehicles BC concentrations was the type of vehicle followed, with diesel buses and delivery trucks that had ground-level exhaust pipes being the worst. Following a gasoline powered car did not increase BC concentrations.

The authors also estimate daily exposure to diesel particulate matter (DPM), concluding that compared to earlier models, "in-vehicle DPM exposures appear to make very significant contributions to overall DPM exposures, randing from approximately 30-55% of total DPM exposure on a statewide, population basis.  Thus the in-vehicle microenvironment may be the most important route of overall DPM exposure, though only 1.5h day-1 is spend there, on average."

Adams 2001 - "Determinants of Fine Particle (PM2.5) Personal Exposure Levels in Transport Microenvironments, London, UK"

Adams, HS; Nieuwenhuijsen, MJ; Colvile, RN
"Determinants of Fine Particle (PM2.5) Personal Exposure Levels in Transport Microenvironments, London, UK"
Atmospheric Environment
September 2001 v.35, n.27; pp.4557-4566
On the Web
Relevance: medium-low

The authors measured concentrations of fine PM on fixed routes using different modes (car, bus, bicycle) in London. They found that route was a significant factor, explaining 20% of the variation, but mode was not. Wind speed explained 18% of the variation. "Personal exposure levels were reasonable correlated with urban background FSM [fixed site monitor] concentrations."

CARB 1998 - "Measuring Concentrations of Selected Air Pollutants Inside California Vehicles"

California Air Resources Board (CARB)
"Measuring Concentrations of Selected Air Pollutants Inside California Vehicles"
December 1998, Contract No. 95-339, Final Report
On the Web
Relevance: medium-low

CARB measured concentrations of various air pollutants inside vehicles as a range-finding experiment. They studied the effect of freeway conditions (rush vs. non-rush), roadway types, vehicle types, air vent settings, time of day, and roadside/ambient air quality.

CARB found that pollutant concentrations were higher:

• in the regular vs. carpool lane
• during rush hour
• when following diesel or other high-emitting vehicles

Other findings include:

• Vent settings and vehicle type did not seem to make a big difference
• "Most pollutants levels, especially the VOC's, were elevated inside and outside the vehicles relative to either the roadside or ambient station concentrations"
• "Particle concentrations were typically significantly higher outside the vehicles than inside, presumably due to losses in the vehicle ventilation systems (and other factors) - while significant differences were not observed between inside and outside levels of gas phase pollutants for the same vehicle."

CAVEAT: this was a preliminary, range-finding study, so we should look at other studies for confirmation and hard numbers.

Rank 2001 - "Differences in Cyclists and Car Drivers Exposure to Air Pollution from Traffic in the City of Copenhagen"

Rank, Jette; Folke, Jens; Jespersen, Per Homann
"Differences in Cyclists and Car Drivers Exposure to Air Pollution from Traffic in the City of Copenhagen"
The Science of the Total Environment
2001; v.279; pp.131-136.
On the Web
Relevance: medium-high

The authors equipt two cyclists and two car drivers with air samplers for 4 hours at a time on 2 days. They found "The concentrations of particles and BTEX in the cabin of the cars were 2-4 times greater than in the cyclists' breathing zone, the greatest difference being for BTEX. Therefore, even after taking the increased respiration rate of cyclists into consideration, car drivers seem tot be more exposed to airborne pollution than cyclists.

Car/bicycle ratio

• Benzene: 2.8
• Toluene: 3.4
• Thylbenzene and Xylenes: 3.7
• Hydrocarbons: 3.7
• Particles (total dust):1.7.

ICTA 2000 - “In-Car Air Pollution: The Hidden Threat to Automobile Drivers"

International Center for Technology Assessment,
“In-Car Air Pollution: The Hidden Threat to Automobile Drivers"
Report No. 4, An Assessment of the Air Quality Inside Automobile Passenger Compartments
Washington, DC: July 2000
On the Web
Relevance: high

This report reviews 23 studies from between 1982 and 1998 covering the main pollutants inside cars: particulate matter, volatile organic compounds, carbon monoxide, nitrogen oxides, and ozone.  For all exhaust pollutants except CO and the largest PM, concentrations are typically higher inside cars in heavy traffic than elsewhere.

Chertok 2004 - “Comparison of Air Pollution Exposure for Five Commuting Modes in Sydney – Car, Train, Bus, Bicycle and Walking”

Chertok, Michael ; Voukelatos, Alexander ; Sheppeard, Vicky ; and Rissel, Chris
“Comparison of Air Pollution Exposure for Five Commuting Modes in Sydney – Car, Train, Bus, Bicycle and Walking”
Health Promotion Journal of Australia
April 2004; v.15,n.1; pp.63-67
On the Web (pdf)
Relevance: high

The study measured the BTEX pollutant and NO2 exposure of 44 subjects on their regular daily commutes, each lasting at least 30 minutes each way.  Car commuters were exposed to the highest levels of BTEX pollutants, while bus commuters were exposed to the highest levels of NO2.  Train (light and heavy rail) commuters were exposed to the lowest levels of all pollutants measured.  Walking and cycling commuters were exposed to significantly lower levels of BTEX than car commuters and of NO2 than bus commuters. 

Batterman 2002 - “Levels and Composition of Volatile Organic Compounds on Commuting Routes in Detroit, Michigan”

Batterman, Stuart A; Peng, Chung-Yu; and Braun, James.
“Levels and Composition of Volatile Organic Compounds on Commuting Routes in Detroit, Michigan”
Atmospheric Environment
December 2002; v.36,n.39-40; pp.6015-6030
On the Web
Relevance: high

Batterman et al measured VOCs in cars and buses during rush hour on commercial, industrial, and residential routes in Detroit, Michigan.  They found that:

• VOC concentrations along roadways and in buses were similar;
• route did not much affect differences in air quality; however, the buses all traveled on congested 4 lane roads during rush hour; and
• VOC concentration varied significantly over time, which the authors attribute to changes in weather, mainly inversions and wind speed and direction;
• vehicle sources dominate industrial sources in influencing urban VOC concentrations, corroborating earlier studies; and
• VOC concentrations on roadways were much higher than concentrations at the two fixed-site monitoring stations in Detroit.  For example, BTEX concentrations measured at the fixed sites were 2-4 times lower than levels measured in traffic.

Kim 2001 - “Concentrations and Sources of VOCs in Urban Domestic and Public Microenvironments”

Kim, Young Min; Harrad, Stuart; Harrison, Roy M.
“Concentrations and Sources of VOCs in Urban Domestic and Public Microenvironments”
Environmental Science and Technology
March 15, 2001; v.35, n.6; pp.997-1004
On the Web
Relevance: high

Concentrations of volatile organic compounds (VOCs) were measured in a wide range of urban microenvironments (including homes, offices, shops, roadsides, buses, trains, and cars) in Birmingham, UK.  Of transportation microenvironments, cars had the highest mean concentrations of most of the VOCs measured; however the automobiles in the study were over 10 years old and smoking occurred in 6 of them during sampling.

Kim 2002 - “Levels and Sources of Personal Inhalation Exposure to Volatile Organic Compounds”

Kim, Young Min; Harrad, Stuart; Harrison, Roy M.
“Levels and Sources of Personal Inhalation Exposure to Volatile Organic Compounds” Environmental Science and Technology
December 15, 2002; v.36,n.24; pp.5405-5410
On the Web
Relevance: medium

Personal exposures to VOCs of 12 urban dwellers (Birmingham, UK) were measured over 5-10 days.  Exposure in the home contributed 50-80% of overall individual exposure to 2 main VOCs, mostly due to the large amount of time spent at home.  Smoking, vehicle use, and heating also contributed noticeably to personal exposure to VOCs.