RedEye hired a local laboratory to randomly test some CTA surfaces for cleanliness and harmful bacteria. Though the tests conducted along the Red Line, Brown Line, No. 66 and No. 151 routes revealed no staph or E. coli bacteria cells, approximately 57 percent of the tested surfaces registered as dirty enough to breed bacteria that can make you sick.

Surfaces tested on Red and Brown Line trains averaged "dirty" readings, though Red Line cars were found to be significantly dirtier than those on the Brown. Among the dirtiest surfaces tested were the upholstered seats on trains and the stop cord on one bus.

The bottom line: Despite the CTA's efforts to keep buses and trains clean, tests show that the potential for bacteria buildup on the "L" and buses is nothing to sneeze at.

Riders who don't wash their hands between riding the CTA and eating are potentially at risk for colds, the flu, cold sores and food-related illnesses, such as salmonella poisoning