Defending champion Victoria Azarenka and third-ranked Serena Williams will be among Sharapova's main opposition as she seeks to win her fifth grand slam title, having completed the set at last year's French Open.

CNN: Sharapova takes on Australian boys

These findings will be of particular concern to cities in the Central Valley of California like Bakersfield and Fresno, which have for years ranked among the highest in the nation for air pollution.

FORBES: Researchers Prove Air Pollution Causes Heart Attacks