Click on image to the right to see information on the toxic effects of diesel fumes as reported by the California Office of Environmental Health Hazard Assessment:
Summary of the California Office of Environmental Health Hazard Assessment (OEHHA)
For more detailed information than provided in the summary below, please read the full posting by OEHHA.
What is deisel exhaust ?
Diesel exhaust contanes "know or suspeted cancer-causing substances, such as bebzuem arsenic, and formaldehyde. It also contains other harmful pollutants, such as nitrogen oxides (a component of urban smog."
How are people exposed to diesel exhaust?
"People living in working in urban and industrial settings are more likely to be exposed to this pollutant." If a warehouse is built on the Peron Howard Street property, the residents of Phillipsburg, particularly in the area of the Flats between Sitgreaves and Howard streets, will be very exposed to the toxic diesel fumes that would come from the potential Howard Street Warehouse.
Due to the geographic contours of the area, it is my suspicion that the negative effects of the diesel fumes from potentially 200 trucks per day would be along the South Main Street corridor from the Red Vandergrift Bridge (aka Black Bridge) to at least the CNJ Greeens Bridge, also affecting the Delaware Heights section of town. Part of this conclusion for the area that would be affected by the diesel fumes from the potetial Peron Howard Street Warehouse comes from anecdotal conversations with residents in this are of town who have complained about consistent issues with pollutants in the air that can be noticed, and the belief of many of the residents that the pollutants are comng from the a manufacturing plant downtown. 
Click on the image to the right to see the enlarged map:
In the map to the right you can see my approximation based on conversations with residents as to my best estimate which areas of town will be most largely affected by the toxic diesel fumes. The area that is shaded red represents the area I believe will be most higley affected by the existence of the Peron Howard Street warehouse.
What are the health effects of diesel exhaust?
Please read the OEHAA posting for a listing of the many other negative heath affects from diesel fumes. I personally have knocked on many doors in this area of town, as have others who do not want to see a warehouse in downtown Phillipsburg aong the Delaware River.
"Diesel exhaust and many individual substances contained in it (including arsenic, benzene, formaldehyde and nickel) have the potential to contribute to mutations in cells that can lead to cancer. In fact, long-term exposure to diesel exhaust particles poses the highest cancer risk of any toxic air contaminant evaluated by OEHHA. ARB estimates that about 70 percent of the cancer risk that the average Californian faces from breathing toxic air pollutants stems from diesel exhaust particles."