Reduced commuter exposure to PM and PAHs in response to improved emission standards in bus rapid transit systems in Mexico.

We evaluated impacts of progressive technological updates to bus rapid transit (BRT) systems on in-cabin concentrations of particulate matter with an aerodynamic diameter ≤2.5 μm (PM2.5), and the various polyaromatic hydrocarbons (PAHs) to which commuters were exposed.

Studying human exposure to vehicular emissions using computational fluid dynamics and an urban mobility simulator: The effect of sidewalk residence time, vehicular technologies and a traffic-calming device.

A computational system consisting of an urban mobility simulator, validated fluid dynamics and an integral exposure model, is proposed to obtain cyclist and pedestrian exposure to PM and NO. Pedestrian activities in the urban anthroposphere include walking and running. The computational experiments take place in a computer-generated urban canyon, subject to emissions from diesel and gasoline Euro 5 and Euro 6 vehicular technologies, in continuous and stop-and-go traffic scenarios, and three wind directions at two speeds.

Sidewalk pollution flows caused by vehicular traffic place children at a higher acute exposure risk.

The objective of this work is to study the immediate transport flows of PM diesel exhaust emissions on a city sidewalk. Under calm conditions largest direct exhaust PM diesel concentrations tend to accumulate at two preferred heights: higher ones at 200-225 cm due to truck and buses aerodynamics, and lower ones at 130-160 cm due to light vehicles. Obtained flows indicate that exhaust emissions are transported to these heights via vortices generated by vehicular traffic.

Real-world emissions of in-use off-road vehicles in Mexico.

Unlabelled: 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 CO EFs of selected diesel-powered off-road mobile sources in Mexico under real-world operating conditions using on-board portable emissions measurements systems (PEMS).

Assessment of the ozone-nitrogen oxide-volatile organic compound sensitivity of Mexico City through an indicator-based approach: measurements and numerical simulations comparison.

The ozone (O3) sensitivity to nitrogen oxides (NOx, or nitric oxide [NO] + nitrogen dioxide [NO2]) versus volatile organic compounds (VOCs) in the Mexico City metropolitan area (MCMA) is a current issue of scientific controversy. To shed light on this issue, we compared measurements of the indicator species O3/NOy (where NOy represents the sum of NO + NO2 + nitric acid [HNO3] + peroxyacetyl nitrate [PAN] + others), NOy, and the semiempirically derived O3/NOz(surrogate) (where NOz(surrogate) is the derived surrogate NOz, and NOz represents NOx reaction products, or NOy - NOx) with results of numerical predictions reproducing the transition regimes between NOx and VOC sensitivities. Ambient air concentrations of O3, NOx, and NOy were measured from April 14 to 25, 2004 in one downwind receptor site of photochemically aged air masses within Mexico City.

A vehicle emissions system using a car simulator and a geographical information system: Part 1--System description and testing.

A methodology for estimating vehicular emissions comprising a car simulator, a basic traffic model, and a geographical information system is capable of estimating vehicle emissions with high time and space resolution. Because of the extent of the work conducted, this article comprises two sections: In Part 1 of this work, we describe the system and its components and use examples for testing it. In Part 2 we will study in more detail the emissions of the sample fleet using the system and will make comparisons with another emission model.

An air pollution modeling study using three surface coverings near the New International Airport of Mexico City.

The dry lakebed of what once was the lake of Texcoco is the location selected for the New International Airport of Mexico City. This project will generate an important urban development near the airport with regional implications on air quality. Using a prognostic air quality model, the consequences of photochemical air pollution in the metropolitan area of Mexico City resulting from three possible coverings for the areas of the lakebed that are not occupied by the runway and terminal building are investigated.

An air quality modeling study comparing two possible sites for the new international airport for Mexico City.

Using an air quality model, two future urban scenarios induced by the construction of the new international airport for Mexico City are compared at a regional level. The air quality model couples the meteorology model MM5 and state-of-the-art photochemistry. The air quality comparison is made using metrics for the criterion gases selected for the study.