The various hydrocarbons enter the atmosphere from a number of different sources. Some of the most important are the following (a) Auto exhaust and partially unburned gasoline (b) Gasoline evaporated in various steps in production, refining, and handling (c) Organic solvents used in manufacturing, dry cleaning fluids, inks and paints (d) chemical manufacturing (e) Incineration of various materials, industrial dryers, and ovens Once the hydrocarbons are liberated into the atmosphere, they can combine with atomic oxygen or with ozone. These reactions result C、O、+O in the formation of peroxyacyl nitrates(PAN, R O N 过氧乙酰硝酸酯). The PANs are strongly oxidizing and account for many of the harmful O properties of smogThe various hydrocarbons enter the atmosphere from a number of different sources. Some of the most important are the following: (a) Auto exhaust and partially unburned gasoline. (b) Gasoline evaporated in various steps in production, refining, and handling. (c) Organic solvents used in manufacturing, dry cleaning fluids, inks, and paints (d) Chemical manufacturing. (e) Incineration of various materials, industrial dryers, and ovens. Once the hydrocarbons are liberated into the atmosphere, they can combine with atomic oxygen or with ozone. These reactions result in the formation of peroxyacyl nitrates (PAN, 过氧乙酰硝酸酯). The PANs are strongly oxidizing and account for many of the harmful properties of smog