Archives 1 - Travel Impacts on Air Quality and Greenhouse Gases
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- The goal of this study was to understand the correlations between traffic variables and air pollutant concentrations at an inner city school site.
- Carbon monoxide has been selected as a representative traffic generated pollutant and the traffic column is used to represent transportation.
- A total of five days data collection was performed from both arterial area and highway in March, 2010.
- CO concentration, traffic volume at local intersection and highway and meteorology data was obtained.
- CO concentration increases in the peak hour time. Good correlations were observed from highway and some local samplings.
Hu, J., M. Lu, et al. (2011). Investigation of Traffic Emissions in the Vicinity of an Inner City Elementary School, ASCE.
- This paper investigates pedestrian exposure to traffic emissions at the Marylebone Road–Gloucester Place intersection in central London, taking a particular interest in the peak exposures occurring within minutes.
- The approach is based on the large eddy simulation modeling methodology, which enables high spatial resolution of air movements and pollutant concentrations to be achieved at relatively moderate computational cost.
- The results show the complexity of the air flows in the vicinity of the intersection at pedestrian height and the large variability of peak exposures due to the turbulent air flows.
- The large variability of peak exposures is found due to the turbulent air flows.
- Inter-trip variability explains residual variability in journey exposure analyses.
Wang, H., R. N. Colvile, et al. (2011). “Understanding peak pedestrian exposures due to traffic emissions within the urban environment.” Transportation Research Part D: Transport and Environment 16(5): 392-401.
- This study is the first bi-national investigation characterizing traffic air pollutants at four schools in El Paso, USA and Cd. Juarez, Mexico. It paired indoor and outdoor concentrations of fine and coarse particulate matter (PM), PM2.5 reflectance [black carbon(BC)], and nitrogen dioxide (NO2) were determined for sixteen weeks in 2008 at four elementary schools (two in high and two in low traffic density zones) in a U.S.–Mexico border community to aid a binational health effects study.
- Strong spatial heterogeneity was observed for all outdoor pollutant concentrations. Concentrations of all pollutants, except coarse PM, were higher in high traffic zones than in the respective low traffic zones. Black carbon and NO2 appear to be better traffic indicators than fine PM. Indoor air pollution was found to be well associated with outdoor air pollution, although differences existed due to uncontrollable factors involving student activities and building/ventilation configurations.
- Results of this study indicate substantial spatial variability of pollutants in the region, suggesting that children’s exposures to these pollutants vary based on the location of their school.
Raysoni, A. U., J. A. Sarnat, et al. (2011). "Binational school-based monitoring of traffic-related air pollutants in El Paso, Texas (USA) and Ciudad Juárez, Chihuahua (México)." Environmental Pollution 159(10): 2476-2486.
- Automobile exhaust pose health risks and dependency on car commuting also reduces physical fitness opportunities.
- This study attempts to quantify the benefits of reducing automobile usage for short urban and suburban trips.
- The authors simulated census-tract level changes in hourly pollutant concentrations from the elimination of automobile round trips ≤ 8 kilometers in 11 metropolitan areas in the Upper Midwestern U.S. using the Community Multiscale Air Quality (CMAQ) Model. Next, they estimated annual changes in health outcomes and monetary costs expected from pollution changes using EPA’s Benefits Mapping Analysis Program (BenMAP). Finally, they used WHO’s Health Economic Assessment Tool (HEAT) to calculate the benefits of increased physical activity if 50% of short trips were made by bicycle.
- The authors estimate that annual average urban PM2.5 would decline by 0.1 µg/m3 and that summer O3 would increase slightly in cities but decline regionally, resulting in net health benefits of $3.5 billion/year (95% CI: $0.4–$9.8 billion), with 25% of PM2.5 and most O3 benefits to populations outside metropolitan areas. Across the study region of approximately 31.3 million people and 37,000 total square miles, mortality would decline by approximately 1,100 deaths/year (95% CI: 856 – 1,346) due to improved air quality and increased exercise. Making 50% of short trips by bicycle would yield savings of approximately $3.8 billion/year from avoided mortality and reduced health care costs (95% CI: $2.7 – $5.0 billion). We estimate that the combined benefits of improved air quality and physical fitness would exceed $7 billion/year.
- Our findings suggest that significant health and economic benefits are possible if bicycling replaces short car trips. Less auto dependence in urban areas would also improve health in downwind rural settings.
Grabow, M. L., S. N. Spak, et al. (2011). "Air Quality and Exercise-Related Health Benefits from Reduced Car Travel in the Midwestern United States." Environmental Health Perspectives.
- This article aims to supplement scarce research on the children’s attitudes to cars and the environment. Assuming that attitudes to cars develop in childhood, this article draws upon the writing assignments and interviews exploring the upper-elementary school children’s attitudes to cars.
- The study was conducted in Amsterdam, The Netherlands, between January and December 2010.
- Briefly examining existing research on children’s environmental attitudes in general, and in relation to cars in particular, the author argues that in-depth qualitative research is essential to the understanding of the factors that explain present attitudes and perhaps predicting the behavior of future drivers.
- In conclusion, the author makes a recommendation for the development of a curriculum addressing the development of children’s awareness of sustainable transportation and the environmental implications of car driving.
Kopnina, Helen. (2011). “Kids and cars: Environmental attitudes in children.” Transport Policy 18(4): 573-578.
- This article examines the role smart growth can play in achieving planning objectives, including energy conservation and emission reductions. It summarizes existing literature on land use impacts on travel activity, energy consumption and pollution emissions. It examines claims that smart growth policies are ineffective and harmful.
- Land use policies can significantly affect transportation options and costs, and therefore travel activity. People who live and work in automobile-dependent locations tend to drive more annual miles, consume more fuel and produce more pollution than they would in more accessible, multi-modal communities. As a result, smart growth reforms can provide various economic, social and environmental benefits.
- Some critics claim that these impacts are small and not cost effective but their analysis tends to misrepresent key issues. The only consider land use density, ignoring the effects of other land use factors such as regional accessibility, land use mix, road and path connectivity, transport system diversity, and parking management. They overlook additional benefits, and growing consumer demand for more accessible, multi-modal home locations. As a result, they underestimate smart growth impacts and benefits.
- This is important because existing land use development policies and planning practices tend to favor sprawl and automobile dependency. Smart growth requires policy reforms that allow more compact and mixed development, support alternative modes, and reduce existing subsidies to automobile such as generous minimum parking requirements. These reforms tend to face institutional inertia and political opposition. It is therefore important to have accurate information on the full potential impacts and benefits of smart growth policy reforms. When all impacts are considered, smart growth policies are often a cost effective way to achieve planning objectives.
Litman, Todd. (2011). “Can Smart Growth Policies Conserve Energy and Reduce Emissions?” Portland State University’s Center for Real Estate Quarterly 5(2): 21-30.
- Vehicular emissions in close proximity to schools can have detrimental health effects on children. The Safe Routes to School program claims to improve air quality through implementation due to reduced volume of traffic generated to schools.
- While a reduced volume of traffic may reduce the amount of emitted pollutants, the program lacks the ability to quantitatively track this air quality improvement.
- A school participating in the Safe Routes to School program was selected based off of health risks associated with a high vehicular volume and the proximity of that traffic to the school. A survey was utilized to generate a vehicle inventory of faculty and parent drivers of this school. The inventory was applied to EPA equations to demonstrate the amount of emissions generated on a daily, weekly, monthly and school year basis. The equation was successful in generating quantitative data that demonstrate the total emissions generated by the school.
- EPA equations can establish pre-emission levels versus post-emissions levels. This comparison demonstrates the effect the program has on reducing emission levels of traffic generated to the school. Once applied on a larger scale, trends and applicability of the program in different regions, demographic areas and community types (rural, suburban and urban) can be identified.
- This identification will enable Safe Routes to School users to invest in individual initiatives that have been successful in similar areas.
Rickman, Joshua C. "A Methodology to Measure Emissions Generated by Automobile Trips to Schools Participating in Safe Routes to School." Landscape Architecture & Regional Planning Masters Projects. Paper 28 (2011).
- Studies have reported high exposure to air pollutants at school, but only a handful of studies have analysed children’s exposure at school.
- Quantifying the contribution of school exposure with observed health symptoms presents further challenges.
- This study finds that children’s classroom exposure to air pollutants is affected by the penetration of outdoor pollutants, wall absorption, emissions from furniture and other materials, level and length of occupancy, and quality of ventilation. This is further exacerbated by the fact that children move around during their school day.
- Findings also indicate that the air pollutant dose intake is affected by daily patterns of physical and traffic activity during and outside school hours which make it difficult to compare the contribution of school-based and non-school-based exposures to the health effect under investigation.
- There is strong evidence that low socioeconomic level is highly correlated with the proximity of the school to pollution sources, yet this area of socioeconomic research has been largely unexplored in the assessment of traffic emission exposure.
Mejía, Jaime F., Choy, Samantha Low, Mengersen, Kerrie, Morawska, Lidia. “Methodology for assessing exposure and impacts of air pollutants in school children: Data collection, analysis and health effects – A literature review.” Atmospheric Environment. 45.4 (2011): 813-823.
- The objective of this study is to examine the relationship between measured traffic density near the homes of children and attained body mass index (BMI) over an eight-year follow up.
- Children aged 9-10 years were enrolled across multiple communities in Southern California in 1993 and 1996 (n = 3318). Children were followed until age 18 or high school graduation to collect longitudinal information, including annual height and weight measurements. Multilevel growth curve models were used to assess the association between BMI levels at age 18 and traffic around the home.
- For traffic within 150 m around the child's home, there were significant positive associations with attained BMI for both sexes at age 18. With the 300 m traffic buffer, associations for both male and female growth in BMI were positive, but significantly elevated only in females. These associations persisted even after controlling for numerous potential confounding variables.
- This analysis yields the first evidence of significant effects from traffic density on BMI levels at age 18 in a large cohort of children. Traffic is a pervasive exposure in most cities, and our results identify traffic as a major risk factor for the development of obesity in children.
Jerrett M, McConnell R, et al. “Automobile traffic around the home and attained body mass index: A longitudinal cohort study of children aged 10-18 years.” Preventive Medicine 2010; 50(S1):S50-S58.
- Commuters are exposed to high concentrations of air pollutants, but little quantitative information is currently available on differences in exposure between different modes of transport, routes, and fuel types.
- The aim of our study was to assess differences in commuters’ exposure to traffic-related air pollution related to transport mode, route, and fuel type.
- The authors measured particle number counts (PNCs) and concentrations of PM2.5 (particulate matter ≤ 2.5 µm in aerodynamic diameter), PM10, and soot between June 2007 and June 2008 on 47 weekdays, from 0800 to 1000 hours, in diesel and electric buses, gasoline- and diesel-fueled cars, and along two bicycle routes with different traffic intensities in Arnhem, the Netherlands. In addition, each-day measurements were taken at an urban background location.
- The study found that median PNC exposures were highest in diesel buses (38,500 particles/cm3) and for cyclists along the high-traffic intensity route (46,600 particles/cm3) and lowest in electric buses (29,200 particles/cm3). Median PM10 exposure was highest from diesel buses (47 µg/m3) and lowest along the high- and low-traffic bicycle routes (39 and 37 µg/m3). The median soot exposure was highest in gasoline-fueled cars (9.0 × 10–5/m), diesel cars (7.9 × 10–5/m), and diesel buses (7.4 × 10–5/m) and lowest along the low-traffic bicycle route (4.9 × 10–5/m). Because the minute ventilation (volume of air per minute) of cyclists, which the authors estimated from measured heart rates, was twice the minute ventilation of car and bus passengers, they calculated that the inhaled air pollution doses were highest for cyclists. With the exception of PM10, inhaled air pollution doses were lowest for electric bus passengers.
- Commuters’ rush hour exposures were significantly influenced by mode of transport, route, and fuel type.
Zuurbier, M., G. Hoek, et al. (2010). "Commuters’ Exposure to Particulate Matter Air Pollution Is Affected by Mode of Transport, Fuel Type, and Route." Environ Health Perspect 118(6).
- Nearly a third of U.S. greenhouse gas emissions in 2007 were transportation-related; each gallon of gasoline used in transportation emits 20 lbs of CO2 into our atmosphere.
- About half of all car trips in the UK, the Netherlands, and the US, are less than 5 miles.
- This commentary focuses on communication enhancements, marketing enhancements, and policy enhancements that communities can make with relative ease to promote active transport.
- There is strong evidence that communication, social marketing, and policy all have considerable potential to yield significant health, quality of life, economic and environmental benefits to communities willing to implement them.
Maibach, Edward, Steg, Linda, and Anable, Jillian. “Promoting physical activity and reducing climate change: Opportunities to replace short car trips with active transportation.” American Journal of Preventive Medicine. 49 (2009): 326-327.
- This study uses Comparative Risk Assessment methods to estimate the health effects of alternative urban land transport scenarios for London, UK and Delhi, India.
- Transport-related greenhouse-gas emissions are increasing, with a rapid growth projection in low-income and middle-income countries.
- Increase in the distances walked and cycled would lead to large health benefits.
- Creation of safe urban environments for mass active travel will require prioritization of the needs of pedestrians and cyclists over those of motorists. Walking or cycling should become the most direct, convenient, and pleasant option for most urban trips.
Woodcock, James, Edwards, Phil, Tonne, Cathryn, Armstrong, Ben G., Ashiru, Olu, Banister, David, et al. “Public health benefits of strategies to reduce greenhouse-gas emissions: urban land transport” The Lancet. 374 (2009): 1930-1943.
- This article highlights Safe Routes to School as a promising strategy for increasing youth physical activity and improving health equity.
- Joint use agreements to unlock school playgrounds after school and on weekends is another highlighted approach to promote physical activity, especially in poor communities and communities without access to other recreation facilities.
- Finally, this article reminds readers that The Recovery Act includes more than $45.5 billion to employ out of work Americans to improve public transit systems, making our communities more walkable and bikable and investing in projects that reduce reliance on automobiles – the source of close to 30% of total greenhouse gas emissions.
Solomon, Loel S., Standish, Marion B., and Orleans, C. Tracy. “Creating Physical Activity-Promoting Community Environments: Time for a breakthrough.” Preventive Medicine. 49.4 (2009): 334-335.
- Exposure to fine-particulate air pollution has been associated with increased morbidity and mortality, suggesting that sustained reductions in pollution exposure should result in improved life expectancy.
- This study directly evaluates the changes in life expectancy associated with differential changes in fine particulate air pollution that occurred in the United States during the 1980s and 1990s.
- Results demonstrate a decrease in the concentration of fine particulate matter with an increase in mean life expectancy. It is estimated that reductions in air pollution accounts for as much as 15% of the overall increase in life expectancy in the study areas.
Pope, Arden C. III, Ezzati, Majid and Dockery, Douglas W. “Fine Particulate Air Pollution and Life Expectancy in the United States.” The New England Journal of Medicine. 360.4 (2009): 376-386.
- Incorporating a health promotion approach in the design and development of the built environment can ease climate change and promote healthier living.
Dannenberg, Andrew L., Morrow Almeida, Heather, Vindigni, Stephen M. and Younger, Margalit. "The Built Environment, Climate Change, and Health Opportunities for Co-Benefits." American Journal of Preventive Medicine. 35.5 (2008): 517-526.
- This paper examines how children’s travel to school is affected by school choice and providing bus service.
- The number of students who walk to neighborhood schools is calculated at more than 6 times greater than the city-wide school.
- In a scenario without buses, city-wide schools have six times fewer children walking to school, 4.5 times more miles traveled, 4.5 times the system cost and 4.5 times the emissions of criteria air pollutants and greenhouse gases.
- Bus service decreases miles traveled and resulting emissions by 60-70% compared to no bus service.
- The authors suggest policy recommendation for neighborhood walkability consider the implications of specific school district choice programs be addressed in conjunction with traffic patterns.
Wilson, Elizabeth J., Wilson, Ryan and Krizek, Kevin J. “The Implications of School Choice on Travel Behavior and Environmental Emissions.” Transportation Research Part D. 12.7 (2007): 506-518.
- This article examines single-use, low-density land use patterns and reports that a 5% increase in neighborhood walkability is associated with:
- 32.1% more minutes devoted to physically active travel
- About one-quarter point lower BMI (0.228)
- About one-quarter point lower BMI (0.228)
- 5.6% fewer grams of Nitrogen Dioxide per capita
- 5.5% fewer grams of volatile organic compound (VOC) emitted per capita
Frank, Lawrence D., Sallis, James F., Conway, Terry L., Chapman, James E., Saelens, Brian E. and Bachman, William. “Many Pathways from Land Use to Health. Associations between Neighborhood Walkability and Active Transportation, Body Mass Index, and Air Quality.” Journal of the American Planning Association. 72.1 (2006): 75-87.
- This article focuses on the relationship between the built environment, travel behavior, and public health outcomes.
Frank, Lawrence D. and Engelke, Peter. “Multiple Impacts of the Built Environment on Public Health: Walkable Places and the Exposure to Air Pollution.” International Regional Science Review. 28(2) (2005): 193-216.
- This study examines the association between traffic-related pollution and childhood asthma among 208 children in 10 communities in Southern California.
- Results demonstrate an association between increased asthma and closer residential distance to a freeway, indicating that respiratory health in children is adversely affected by local exposures to outdoor Nitrogen Dioxide or other freeway-related pollutants.
- The implications of these data are important and relevant because they strengthen emerging evidence that air pollution can cause asthma and that traffic-related pollutants are partly responsible for this association.
Gauderman, James W., Avol, Edward, Lurmann, Fretd, Kuenzli, Nino, Gilliland, Frank, Peters, John, and McConnell, Rob. “Childhood Asthma and Exposure to Traffic and Nitrogen Dioxide.” Epidemiology. 16.6 (2005): 737-743.
- Adoption and maintenance of healthy lifestyles by substituting walking or biking for short trips currently taken by car could simultaneously improve health and reduce oil consumption and carbon dioxide emissions.
- Substitution of cycling for driving for short trips has the potential to reduce gasoline demand up to nearly 34.9% of current domestic oil consumption.
Higgins, Paul A.T. and Higgins, Millicent. “A Healthy Reduction in Oil Consumption and Carbon Emissions.” Energy Policy. 33 (2005): 1-4.
- Because of travel behavior differences, school location has an impact on air emissions.
- Centrally located schools that can be reached by walking and bicycling result in reduced air emissions from driving.
"Travel and Environmental Implications of School Siting." October 2003. United States Environmental Protection Agency.
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