The air pollution impacts are likely to be quite severe for anyone who lives near Hahamongna or within a mile of the 210 freeway. That means most residents of La Canada Flintridge, western Altadena, and most of Pasadena.
A recent LA Times editorial states, "pollution concentrations along LA freeways are 5 to 10 times higher than elsewhere." And, the California Air Resource Board states that, "Pollutants from cars and trucks can drift more than a mile from Southern California freeways, suggesting that air pollutions effects could be more widespread".
In August the Southern California Air Quality District announced that it will begin monitoring the air quality along freeways in order to measure nitrogen oxides, fine particles and carbon monoxide. Freeway Pollution
Particulate from diesel burning trucks can have serious health impacts if inhaled. EPA is especially concerned with schools and child care centers near major roads. There will be a country-wide measuring of these particulates, called NEXUS research.
"Results of this NEXUS research on the interactions between air pollution and health effects can have wide-ranging importance. State highway planners and environmental agencies can assess the current vehicle emissions and project the impacts of future road construction projects. Federal, state, and local governments and organizations can make better public health decisions on siting major community developments near roadways. Policy makers can develop better plans to reduce exposures to air pollution for people living near roadways. Even individuals can use these results to make more informed decisions on where they may wish to live."
Here is the US Environmental Protection Agendy's assessement of air pollution near freeways: Air Pollution. Diesel Exhaust