Primary gas- and particle-phase emissions and secondary organic aerosol production from gasoline and diesel off-road engines.

Dilution and smog chamber experiments were performed to characterize the primary emissions and secondary organic aerosol (SOA) formation from gasoline and diesel small off-road engines (SOREs). These engines are high emitters of primary gas- and particle-phase pollutants relative to their fuel consumption. Two- and 4-stroke gasoline SOREs emit much more (up to 3 orders of magnitude more) nonmethane organic gases (NMOGs), primary PM and organic carbon than newer on-road gasoline vehicles (per kg of fuel burned).

Assessment of personal exposure to ozone in asthmatic children residing in Mexico City.

Objective: A study was conducted to evaluate personal ozone exposure (O3p) among asthmatic children residing in Mexico City.

Material And Methods: A total of 158 children were recruited from December 1998 to April 2000. On average, three O3p measurements were obtained per child using passive badges.

Measurements of personal exposure to nitrogen dioxide in four Mexican cities in 1996.

Nitrogen dioxide is a ubiquitous pollutant in urban areas. Indoor NO2 concentrations are influenced by penetration of outdoor concentrations and by indoor sources. The objectives of this study were to evaluate personal exposure to NO2, taking into account human time-activity patterns in four Mexican cities.

Evaluation of human exposure to ambient PM10 in the metropolitan area of Mexico City using a GIS-based methodology.

The main goal of this study was to evaluate the magnitude of outdoor exposure to fine particulate matter (PM10) potentially experienced by the population of metropolitan Mexico City. With the use of a geographic information system (GIS), spatially resolved PM10 distributions were generated and linked to the local population. The PM10 concentration exceeded the 24-hr air quality standard of 150 microg/m3 on 16% of the days, and the annual air quality standard of 50 microg/m3 was exceeded by almost twice its value in some places.

Effects of grades and other loads on on-road emissions of hydrocarbons and carbon monoxide.

This project was developed to assess driving patterns that promote high emissions episodes, also known as emission excursions, particularly while driving on roads with grade. An instrumented vehicle was equipped to record driving conditions such as speed and grade, as well as measure emission rates of total hydrocarbons and carbon monoxide. Controlled runs with predetermined cruise speeds between 35 and 55 mph and accelerations less than 3.