Coastal cities in Southern California are latching on to a new, relatively cheap way to combat pollution running off their streets into the ocean — the little-heralded street sweeper. Street sweepers of 20 years ago did little more than collect litter and big dirt particles. Sweepers are now equipped to vacuum up pesticides, fertilizers, animal droppings, automotive byproducts, and other yuckies that have made it to the street but not yet to the storm drain. Some cities are so excited by the solution that they want to double the number of times streets are swept. John Hoskinson of the enviro group Surfrider Foundation said the sweepers were “a positive step,” but cities should also take steps to prevent the pollution from happening in the first place.