Thanks to concerted efforts in Southern California to reduce emissions over the last nine years, the risk of getting cancer from air pollution has dropped an average of over 50 percent, according to a new study.

In decades past, it was a common occurrence for smog to obscure the skyline in the region. The toxic levels of pollution in the air resulted in significant risks for the development of cancer simply because people were breathing. These effects were especially present in the ports in and around Los Angeles and Long Beach.

A major reason cited for the improved air quality is the changes that have led to fewer vehicular emissions, including diesel powered vehicles. Diesel particles and benzene are still present in the air in significant enough quantities to pose some risk of cancer development.

But evidence from the latest study shows that the risk is definitely decreasing. Only 418 out of every 1 million California residents who have called the state home for at least 70 decades are projected to get air pollution related cancer. This is compared to the 1,194 additional people out of 1 million at risk as recently as 2005.

The study is the fourth to be conducted since 1987 on the subject and many experts feel that the cancer risk is largely under reported. The California Office of Environmental Health Hazard Assessment suggests that the risk may actually be three times higher than currently estimated.

Even with the possible adjustments to the risk of cancer present, researchers assert that the findings of their study still stand. Changing the rate of risk won’t change how much the risk has dropped, they said.

The ports containing the highest concentration of pollution are even showing dramatic improvement. These areas started out with double the risk of surrounding areas, yet changes in the diesel operated vehicles and pollution reducing efforts involving cargo ships have rendered pollution levels much lower. So much lower as to yield rates comparable to the 2005 level risks of areas much further inland.

The overall reduction in air pollution cancer risks fell on average between 57 to 64 percent.