By definition, it occurs when pores of skin are plugged, where natural oil, called sebum, can't reach pore's surface.

Doctors believe that it could be overproduction of sebum that contributes to clogging of pores, which results in formation of pimples and zits. All of this occurs especially around time of puberty, adolescence and even into adulthood.

Problems with severe acne can go on for years, even into one's forties or fifties.

The sebaceous glands, which produce sebum, connect to hair follicle. Breakouts of pimples and/or zits on face, upper-back and chest are most common in this are because this is where glands are most active.

While acne isn't a deadly disease, per se, it can lead to problems later for those who've been inflicted by it. Whiteheads and blackheads can last for an extended period of time, causing irritation and inflammation.

Asphalt technology in California has been changing since creation of Hot Mix Asphalt and will continue to change as time permits. Asphalt rubber pavement was introduced in 1991, which shocked many industry experts. Asphalt rubber pavement seemed promising to those in industry who were ready for a change. On other end of spectrum were industry experts who thought that world wasn't ready for such technologies to be implemented.

In Tom Kuennens article titled, "Asphalt Rubber Makes a Quiet Comeback" shown in Better Roads Magazine, he describes rubber asphalt as, "a chemically reacted mix of liquid asphalt binder with 15 to 22% crumb rubber. The rubber is obtained from reclaimed tires, and added to liquid asphalt. It's reacted at elevated temperatures prior to being mixed with aggregate."