Allegheny and Westmoreland counties, and the rest of southwestern Pennsylvania, show higher mortality rates for multiple sclerosis, while Allegheny County also has higher rates of mortality for various cancers when compared with state rates.
Scientific literature is sparse on links between multiple sclerosis and environmental exposure, but studies do suggest particulate pollution can trigger, aggravate or cause relapses of the autoimmune disease, with further research suggesting that increased incidence of other autoimmune diseases could be linked to indoor and outdoor environmental exposures.
Multiple sclerosis is a gene-based disease triggered by infection or viruses but also with potential for environmental triggers. The chronic disease leads to destruction of myelin -- the insulation around nerves -- which affects nerve signaling that can lead to numbness and impairments in speech, muscle control and coordination, vision and bladder control.
From 2000 through 2008, the age-adjusted death rate for multiple sclerosis in Allegheny County exceeded the state average by 40 percent, with 235 actual deaths compared with 168 expected deaths, based on state Department of Health mortality data.
The state database shows excess death rates for multiple sclerosis in Allegheny County for 2003 and from 2006 through 2008. Westmoreland County also experienced a 41 percent increase in MS deaths over the same nine-year period, with a total of 76 deaths compared with the expected state rate of 54.
For the 14-county area, the mortality rate for MS is 34 percent over expected state totals, with 482 actual deaths from 2000 through 2008, compared with an expected state death rate of 360.
"There certainly is an explanation somewhere. It's a matter of finding it," said Nicholas LaRocca, vice president of health-care delivery policy research at the National Multiple Sclerosis Society.
He said the state method of documenting MS deaths was important -- whether MS was listed as a contributor to or cause of death. Death certificates can be unreliable methods of verifying such deaths, he said.
More research is needed, Dr. LaRocca said, calling for a statewide registry of MS cases to help with research.
Among studies that have linked MS with pollution, a 2003 Finnish study concludes that poor air quality may make people who have MS more susceptible to relapses and infections.
Stacey A. Ritz, a research professor at the Northern Ontario School of Medicine, said in her 2010 study that "the dramatic rise" in incidence of autoimmune diseases cannot be explained by genetics, strongly implicating environmental factors.
"Although there is only a small amount of published data directly examining a possible causal relationship between air pollution exposure and autoimmunity, data from related fields suggests that it could facilitate autoimmunity as well.
"If correct, this hypothesis could prove to have sizable public health implications," she said.
Among other diseases, several types of cancer, including total cancers, also had higher death rates or incidence rates in Allegheny and Washington counties than what state rates would predict.
Asthma long has been a medical concern in polluted regions with increased emergency room visits and hospitalizations occurring on days of poor air quality.
Dr. Fernando Holguin, professor of medicine at the UPMC Montefiore Hospital, came to Pittsburgh to focus on asthma research. He's embarked on a study based at three local high schools -- South Allegheny, Woodland Hills and Clairton -- to help determine links between students' asthma rates and pollution exposure.
The mortality rate of asthma is not notably higher in the region and typically claims only about two people of every 100,000. The biggest concern with asthma is providing timely treatment, especially during poor air-quality days. There's growing concern about asthma incidence in children living in polluted regions.
Dr. Holguin said research must be completed before public policy decisions can be made regarding health effects related to traffic and smokestack pollution.
"There are real concerns that the asthma burden may be increased in this area," he said. "Based on previous surveys, there is an increased burden of asthma in areas that are most polluted."