Physics professor Tom Cahill monitored the air quality around the heavily traveled intersection of Watt and Arden in Sacramento, close to Arden Middle School. He found that ultra fine toxic particles from cars were more significant there than they were around freeways like Interstate Five.
"We were surprised in our first studies how high the levels were that they were actually higher there than they were downwind of I-5 but when we analyzed the area and realized how close the roadway was to the dwellings and to the schools then all of a sudden it started to make sense."
Cahill’s report recommends planting vegetation on median strips to help filter particulate waste and upgrading indoor filters for nearby homes, schools and businesses. His study cautions against street widening projects which he says would just attract more traffic.