title: Real-world emissions of in-use off-road vehicles in Mexico.
abstract: Off-road vehicles used in construction and agricultural activities can contribute substantially to emissions of gaseous pollutants and can be a major source of submicrometer carbonaceous particles in many parts of the world. However, there have been relatively few efforts in quantifying the emission factors (EFs) and for estimating the potential emission reduction benefits using emission control technologies for these vehicles. This study characterized the black carbon (BC) component of particulate matter and NOx, CO, and CO2EFs of selected diesel-powered off-road mobile sources in Mexico under real-world operating conditions using on-board portable emissions measurements systems (PEMS). The vehicles sampled included two backhoes, one tractor, a crane, an excavator, two front loaders, two bulldozers, an air compressor, and a power generator used in the construction and agricultural activities. For a selected number of these vehicles the emissions were further characterized with wall-flow diesel particle filters (DPFs) and partial-flow DPFs (p-DPFs) installed. Fuel-based EFs presented less variability than time-based emission rates, particularly for the BC. Average baseline EFs in working conditions for BC, NOx, and CO ranged from 0.04 to 5.7, from 12.6 to 81.8, and from 7.9 to 285.7 g/kg-fuel, respectively, and a high dependency by operation mode and by vehicle type was observed. Measurement-base frequency distributions of EFs by operation mode are proposed as an alternative method for characterizing the variability of off-road vehicles emissions under real-world conditions. Mass-based reductions for black carbon EFs were substantially large (above 99%) when DPFs were installed and the vehicles were idling, and the reductions were moderate (in the 20-60% range) for p-DPFs in working operating conditions. The observed high variability in measured EFs also indicates the need for detailed vehicle operation data for accurately estimating emissions from off-road vehicles in emissions inventories.
  
  
  
  Measurements of off-road vehicles used in construction and agricultural activities in Mexico using on-board portable emissions measurements systems (PEMS) showed that these vehicles can be major sources of black carbon and NOX. Emission factors varied significantly under real-world operating conditions, suggesting the need for detailed vehicle operation data for accurately estimating emissions inventories. Tests conducted in a selected number of sampled vehicles indicated that diesel particle filters (DPFs) are an effective technology for control of diesel particulate emissions and can provide potentially large emissions reduction in Mexico if widely implemented.
authors.affiliation: a Molina Center for Energy and the Environment , La Jolla , CA , USA.
authors.forename: Miguel
authors.initials: M
authors.lastname: Zavala
authors.affiliation: b Instituto Tecnológico de Monterrey , Monterrey , Mexico.
authors.forename: Jose Ignacio
authors.identifier: 0000-0003-4508-6453
authors.initials: JI
authors.lastname: Huertas
authors.affiliation: b Instituto Tecnológico de Monterrey , Monterrey , Mexico.
authors.forename: Daniel
authors.initials: D
authors.lastname: Prato
authors.affiliation: c Universidad Nacional Autónoma de México , Mexico City , Mexico.
authors.forename: Aron
authors.initials: A
authors.lastname: Jazcilevich
authors.affiliation: d Instituto Nacional de Ecología y Cambio Climático , Mexico City , Mexico.
authors.forename: Andrés
authors.initials: A
authors.lastname: Aguilar
authors.affiliation: e Ambientalis , Mexico City , Mexico.
authors.forename: Marco
authors.initials: M
authors.lastname: Balam
authors.affiliation: f California Air Resources Board , Sacramento , CA , USA.
authors.forename: Chandan
authors.initials: C
authors.lastname: Misra
authors.affiliation: a Molina Center for Energy and the Environment , La Jolla , CA , USA.
authors.forename: Luisa T
authors.initials: LT
authors.lastname: Molina
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis; D002248:Carbon Monoxide / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D008800:Mexico; D009589:Nitrogen Oxides / Q000032:analysis; D015541:Off-Road Motor Vehicles; D053260:Soot / Q000032:analysis*; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D009589:Nitrogen Oxides; D053260:Soot; D001335:Vehicle Emissions; D002245:Carbon Dioxide; D002248:Carbon Monoxide