Taking a pleasant stroll in the city? Read this first.
Ruth, get a life.
Lawn mowers, leaf blowers, and weed eaters probably spread considerable mold and bacteria in the air too. My neighbor mowed the weeds in front of her house along the gravel parking area. I started coughing and sneezing for hours and ended up buying hepa filters for my house at a cost of about $160 (for 3 filters). I worked with a guy who had to abandon his house at a total loss because of mold. His wife came down with some kind of non-specific lung condition and almost lost her job due to the illness. He ripped out the sheetrock, insulation, flooring, and it was all the way to the framing. By the time the clean up was over it cost more than the lot was worth. He ended up buying another house while trying to figure out what to do with the damaged house.
Unidentified pollutants such as bacteria and mold may turn on disease that would otherwise lay dormant such as MS, or MD. The thing about dog feces it it should be cleaned up the the dog owner. Dog owners who don't do so should be fined.
Lawns are one of the biggest water wasters in the suburbs and should be replaced with xeriscape.