How would the air quality for people living and working in the immediate surroundings of the rail yard and warehousing be affected?

Just the intermodal would produce 18 metric tons per year of Volatile Organic Compounds called diesel soot (according to the Environ study submitted to the Army Corps of Engineers by BNSF).  That figure would double with the first phase of warehousing fully occupied.  The EPA states that diesel exhaust remains in the atmosphere for days to weeks over a five-mile radius and that it ahs an accumulative factor.  Further, their studies have found that diesel exhaust causes cancer and asthma.  A study funded by the Department of Transportation states that 32 trucks idling in a 24-hour period exceeds the NEPA level of concern.  The health risks from diesel exposure are greatest for children, pregnant women, the elderly, people with respiratory problems and people who engage in regular strenuous exercise in diesel-polluted areas.  The effects would be even more sifnificant on the people and environment in the on-mile radius.  That raidus includes two schools and many people's homes. 

Child with Asthma, from NRDC, With Every Breath You Take

Trucks idling outside Port of LA

Trucks idling at an inspection station