The document discusses engine exhaust emissions, including the formation of nitrogen oxides, hydrocarbons, carbon monoxide, and particulate emissions. It describes methods for controlling these emissions, such as three-way catalytic converters and particulate traps. The document also covers equipment for measuring emissions of hydrocarbons, carbon monoxide, nitrogen oxides, smoke, and particulate matter. These include chemiluminescence, NDIR, and flame ionization methods for gases, as well as obscuration, continuous filter, Hartridge smokemeter, spot filtering, and Bosch smokemeter techniques for smoke and particulate measurements.