Air pollution damages materials, but it has changed dramatically in the past century, with a reduction in the concentration of corrosive primary pollutants in urban atmospheres. At the same time, architectural styles and types of materials have changed, as we have moved to more organically rich, photochemically active atmospheres. Contemporary air pollutants have the potential to degrade organic coatings and polymers, which are of great importance to modern structures, while increasing amounts of fine diesel soot spoil the simple lines and smooth areas characteristic of many modern buildings |