It doesn't produce smog, not directly.

This just means that it produces less smog and releases less toxic air pollutants, which we'll talk about more [source: EPA].

Unburnt gasoline and evaporation from the tank, when in the atmosphere, react in sunlight to produce photochemical smog.

The president's plan would set caps at power plants for two major pollutants - nitrogen oxide, which produces smog, and sulfur dioxide, the source of acid rain.

Those emissions combine in the atmosphere to produce smog, while also poisoning lakes and killing fish, especially in the Adirondacks.

BP Amoco's goals are to help reduce emissions that produce ground-level ozone, or smog, and to attract more customers.

Nitrogen oxides lead to smog and acid rain, and hydrocarbons produce smog.

The California standard sets lower limits on hydrocarbons and oxides of nitrogen, which produce ground-level ozone, or smog, when baked in the sun.

Motor vehicles are a major source of the pollutants that produce smog.

Most of those, Ms. Cradic said, were for nitrogen oxides, which produces ground-level ozone, or smog.