Winter in Chicago always seems to become interminable this time of year. We haven't seen the ground in more than a month, and our usually vibrant city is colorless and ugly, made dull by a film of snow and ice, road salt, and "city sludge" that covers every available surface. The unmelted snow is a blank canvas for all the filth and pollution generated in this city; every bit of territory marked by the neighborhood dogs is instantly visible along the deep snow banks, and the discolored snow by the roadside ranges from a weak coffee brown to charcoal black. Have you ever noticed how starkly a freshly washed car stands out against the dull winter landscape? Even then, the color doesn't stay true for long. I washed my car just two days ago, and it is once again the color of grime, with only a hint of red.
Has anyone else wondered what causes snow to turn that color? It's not dirt, people-- the ground has been frozen solid for months. It's a combination of the soot and particulates belched out by countless car and truck exhausts, fragments of rubber from car tires, and even specks of concrete and blacktop that have unintentionally dissipated from the roadways and fallen from the overpasses. This is a direct result of the repeated plowing and salting that city streets endure each winter, which in turn creates potholes, cracks in the infrastructure, and yes, countless blown-out tires. This pollution, some of which is absorbed by flowering plants and trees or washed away by cleansing rains during the warmer months, stares us in the face each winter, soiling even fresh snowfall like dust on the fingertip of a white kid glove.
Despite efforts to "green" the city, during the months that aren't actually green, the pollution has nowhere to hide. Chicago was nicknamed "the Black City" during the Golden age (around the turn of the twentieth century) because of the smoke and soot generated by trains, iron and steel plants, slaughterhouses, and other industries, which covered nearly everything downwind. Pollution management has gotten unquestionably better since then, but despite these improvements, the city still has a long way to go. Although the sources may be different now, the outcome is the same; extensive pollutants in the Windy City.