Saturday, September 4, 2010

CPANA Gets Second Lewisville Air Quality Screening Results


Central Park Area Neighbors Association (CPANA) this week received the second set of air quality screening results in its planned year-long benchmarking of Lewisville ambient air prior to the beginning of gas drilling activities in Southern Lewisville.

You can read more about the sampling and testing methodology in CPANA's post on the first sample.

No concentrations were found to exceed any health-based comparison values. For conservative comparison, we used TCEQ's Long Term ESLs (LTESL)


Benzene was detected at .08 ppb. LTESL is 1.4 ppb

Pinene was the most abundent VOC detected, at .14 ppb. (This is a natural compound from pine trees, which are located near our sample box)

Hexadecane was found at .10 ppb. This compound is a 16-carbon alkane also known as cetane. Hexadecane is a diesel component or additive. (LTESL 350 ug/m3 - no ppb value available)

Dichlorodifluoromethane was found at .09 ppb, though our laboratory is not accredited on that compound. This CFC is otherwise known as Freon 12 or R-12. It was used in vehicle air conditioners made before 1994, and its manufacture has been banned. LTESL is 1000 ppb.

Toluene was found at 0.06 ppb. Toluene is a solvent, but EPA says the principal source of toluene in ambient air is automotive emissions. LTESL is 330 ppb.

Heptadecane was found at 0.06 ppb. TCEQ doesn't list a ppb LTESL for heptadecane, but the long-term ESL is listed as 10 ug/m3. We calculate our sample was about 0.56 ug/m3.

p-Xylene was found at 0.06 ppb. LTESL based on odor is 42 ppb. STESL (health) is 58 ppb.

Octadecane was found at 0.05 ppb. LTESL is 10 ug/m3

o-Xylene was found at 0.05 ppb. LTESL based on odor is 42 ppb. STESL (health) is 380 ppb.

Pentadecane was found at 0.04 ppb. No LTESL is found at this point, but we'll research this further. Pentadecane is a component of diesel fuel, and a fragrance agent.

Note that other compounds likely were present, but only the top 10 found are being quantified in our screening, and the laboratory has limits of detection. So any other compounds would have been at concentrations lower than the 0.04 ppb of Pentadecane.