Environment

Rush Hour Pollution Much Higher Than Initially Thought

rush-hour

Measurements of pollutants that cause oxidative stress inside cars during rush hour traffic has revealed results that are potentially alarming. The levels of some of the harmful particulate matter inside a car cabin was found to be double that than was previously estimated.

Traffic pollution sensors are normally placed on the ground next to the road and take continuous readings for 24 hours. Exhaust composition does however change so fast that drivers experience different conditions inside a vehicle than what is measured by roadside sensors. Sampling over a longer period also does not detect changes caused by environmental conditions and road congestion.

Researchers from Emory University, Duke University and the Georgia Institute of Technology explored the pollutants that drivers are actually exposed to during morning rush hour in downtown Atlanta by placing specially designed sampling devices on the passenger seats of cars during commutes.

The devices sensed double the amount of particulate matter that the roadside sensors detected. The team also established that the pollution contained double the amount of chemicals that cause oxidative stress. These chemicals are believed to contribute to the development of many illnesses, including cancer, heart and respiratory disease and various neurodegenerative diseases.

Michael Bergin, professor of environmental and civil engineering at Duke noted that the team found that people might be getting a double dose of exposure in terms of health during rush hour. If the chemicals are indeed as bad as many researchers believe, people should seriously rethink their commuting habits.

Roby Greenwald, who was a research assistant professor at Emory at the time, built a device for the experiment. The device pulls in air at a rate similar to human lungs to detect the levels of pollution. The device was secured to the passenger seat of more than 30 cars as they each completed more than 60 journeys in rush hour.

While some drivers took routes on the highway, others used busy roads in downtown Atlanta. Other details like having windows rolled down and speed varied, but all of the tests found more risk in air exposure than studies conducted with roadside sampling devices did previously.

Heidi Vreeland, a doctoral student in Bergin’s lab and first author of the paper explained that there are many reasons why an in-car air sample would detect higher levels of certain types of air pollution. The chemical composition of exhaust varies dramatically, even in the space of a few feet. Sun heating the roadways also causes an updraft that lifts pollution higher into the air.

Reactive oxygen pollution types found in the study could cause the body to manufacture chemicals that will deal with the reactive oxygen and the same response is caused by particulate matter. When combined, the exposure results in an overreaction that might be destructive to DNA and healthy cells.

Oxidative stress is believed to play a big role in a wide range of diseases including ADHD, Asperger’s syndrome, Parkinson’s disease, cancer, heart failure, Alzheimer’s disease, heart attack, atherosclerosis, autism, sickle cell disease, chronic fatigue syndrome, infection and depression. Antioxidant foods are supposed to address oxidative stress.

Bergin also noted that although there is still a lot of debate about the types of pollution that are cause for the biggest concern and what makes them so dangerous, the bottom line is that driving during rush hour is even worse than what was initially thought.

Greenwald, who is now an assistant professor of environmental health at Georgia State University, added that he believes that this is really an urban planning failure. In Atlanta, the poor air quality on the highways is caused by the fact that 6 million people live in the metro area, and many of them have little choice but to get into a car to go to work, school or the store. Transportation plans that are auto centric do not scale well to cities this size and this is but one more example of how traffic could affect your health negatively.

The results of the study were published in the journal Atmospheric Environment.