There's more scientific research on the hazardous impacts of air pollution. Researchers at the Universirty of California, Los Angeles School of Public Health have found that living near traffic pollution during pregnancy and the first year of life might increase the likelihood of developing childhood cancer.

The study has yet to provide evidence that traffic pollution causes childhood cancer, but it does suggest exposure increases risk.

Researchers have collected data on children diagnosed with cancer before the age of six and their local traffic exposure. The higher the level of traffic pollution, the higher the odds for acute lymphoblastic leukemia (white blood cell cancer), germ cell tumors (cancers of the testicles, ovaries and other organs) and eye cancer, according to their study. The study has yet to provide evidence that traffic pollution causes childhood cancer, said lead researcher Julia Heck, an assistant researcher in the department of epidemiology, adding that the study does suggest exposure to traffic pollution might increase risk for childhood cancers.

Southern California is known for its smog. The state's topography and its warm, sunny climate form and trap air pollutants and create smog, according to the California Air Resources Board. For Dr. Rubin Cohen, director of Adult Cystic Fibrosis and Bronchiectasis Center at the Long Island Jewish Medical Center in New Hyde Park, NY, there's yet to be a direct correlation between smog and childhood cancer. "There has been an association between air pollution and other diseases," Cohen said. "We know that pollution causes asthma, and that is probably more real than the cancer issue."

Children exposed to air pollution are at higher risk of getting asthma, according to findings from researchers in Europe who studied children in 10 cities. Another study at a Southern California university has found that autism in children is another risk factor for those living in high air pollution zones.

As for cancer, the World Health Organization has linked exposure to air pollution from diesel engines to lung and bladder cancers. So, until tailpipe emissions are substantially reduced, those living living near traffic-packed roads – especially pregnant women and families with young children – are at risk.