Air quality study shows vehicles the main polluters in GarCo |

Air quality study shows vehicles the main polluters in GarCo

If preliminary results of a countywide air quality survey are any indication, cars and trucks, not oil and gas, are the major contributors to air pollution.

Results of the county-funded study were presented at a public meeting Sept. 28 in Rifle.

Air samples are collected from monitoring stations spread out across the county, from the old high school in Parachute, to the Henry Building in Rifle and the courthouse in Glenwood Springs. Monitors have also been installed near homes directly adjacent to oil and gas operations, county oil and gas liaison Doug Dennison said.

Samples are analyzed for two major sources of air pollution, PM10 and volatile organic compounds.

PM10 are particulate matter that is 10 microns in size or greater. It can be dust, dirt, or sand in the air and can cause such health problems as chronic bronchitis.

The Environmental Protection Agency has set air quality standards that should not exceed an average of 50 micrograms per cubic meter of PM10 a month. Concentrations of PM10 should not exceed 150 micrograms per cubic meter in a 24-hour period, Dennison said.

“We’ve got four months of data and we haven’t had any (samples) exceed the 24 hour standard of 150 micrograms per cubic meter, Dennison said. “Nothing even close.”

Volatile organic compounds, including hydrocarbon chemicals emitted in natural gas production, are toxic air pollutants from autos, petroleum industries, dry cleaning, fire places, and natural combustion, among other sources.

Six locations in the county were sampled for VOCs.

Dennison said the VOC monitors were located in places where he received complaints from residents about odors from oil and gas operations or where people have reported health problems they believe are related to oil and gas operations. VOCs are emitted from condensate tanks which separate hydrocarbons from the natural gas.

Also a significant source of VOCs are the hydrocarbons emitted “every time we start our cars,” Dennison added.

VOC monitors are now sampling air in the areas of the county where gas drilling is most active ” Grass Mesa, Dry Hollow and Divide Creek, as well as the county landfill near Anvil Points.

“We can’t do it everywhere because we don’t have the money or the resources to do it,” Dennison said.

He also explained there are no set standards for VOC levels as there are for PM10. Samples are evaluated “on a health risk basis where concentrations are compared to established risk levels” for cancer, he said. Below a given level the risk index for cancer is insignificant. A middle level indicates the concentration of VOCs bears watching, and above a certain level, action must be taken because of a serious health risk.

“Most samples were below the level of concern. We had a coupe hits (in the middle level), but there was nothing close to the level of concern.”

The higher results, Dennison said, came not from locations close to oil and gas activities but in more populous areas where vehicle emissions contribute hydrocarbons to the air.

“We’re trying to structure the program to look at both these sources,” Dennison said.

Next year, ozone monitoring will be added to the sampling program. Ground-level ozone poses a significant health risk, especially for children with asthma and it’s a main ingredient of urban smog.

Data from the air quality survey will also be evaluated in conjunction with the health risk assessment survey now under way in the county.

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