Hydrocarbons A group of chemicals containing hydrogen and carbon that often contribute to air pollution as OC's or VOC's They are involved in forming ozone, and some hydrocarbons are toxic Term often used interchangeably with VOCs
Hydrocarbon Chemicals, such as gasoline, formed by the union of carbon and hydrogen
Acronym for unburned hydrocarbons They are at their worst with very rich or very lean mixtures They combine with NOx in sunlight to form photochemical smog
Hors de commerce An impression pulled outside the edition Not intended for sale, it is designated for the artist's or publisher's use An entire edition may be printed for this purpose
High Capacity A projectile for use against lightly armored targets Contains a relatively large amount of explosive as compared to an armor piercing projectile