Do air emissions from
compressor stations
pose serious health
risks?
Pipeline Safety Trust Conference
November 21, 2008
Chris Nidel, MS, JD
Serious?
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Risk?
serious |ˈsi(ə)rēəs| adjective
1 (of a person) solemn or thoughtful in character or manner : her face grew
serious.
• (of a subject, state, or activity) demanding careful consideration or
application : marriage is a serious matter.
• (of thought or discussion) careful or profound : we give serious
consideration to safety recommendations.
• (of music, literature, or other art forms) requiring deep reflection and inviting
a considered response : he bridges the gap between serious and popular
music.
2 acting or speaking sincerely and in earnest, rather than in a joking or
halfhearted manner : suddenly he wasn't teasing any more—he was deadly
serious | actors who are serious about their work.
3 significant or worrying because of possible danger or risk; not slight or
negligible : she escaped serious injury.
risk |risk|noun
a situation involving exposure to danger
the possibility that something unpleasant or unwelcome will happen
Air Emissions of
Concern
Formaldehyde - Reasonably anticipated to be a
human carcinogen (NTP), genotoxic
Acetaldehyde - Reasonably anticipated to be a
carcinogen (NTP), genotoxic
Acrolein - weakly positive for genotoxic assays
PM - respiratory toxicant, cardiac disease
NOx, Methane, CO, CO2, - asthma, secondary
particulates, greenhouse gases, etc.
Dose Makes the
Poison?
General premise of toxicology that the dose makes
the poison
The idea is that many things are toxic at some
dose
However, not all doses of toxic substances have
toxic effect
Poison Makes the
Dose?
How general is the general premise?
Very little is known about synergistic and
compound exposures.
Children and other populations may be significantly
more susceptible to exposures at the same dose
Exposures to genotoxic compounds do not play by
the rules
Cancer, Genotoxins,
and No-threshold Effects
Genotoxicity is the presumed mechanism of many
carcinogens
Theoretically, one molecule of a genotoxic compound
(e.g. formaldehyde, acetaldehyde) can cause a
mutation --> leading to cancer
This theoretical possibility leads to the conclusion that
there is no “safe” exposure to genotoxins or
carcinogens
This means that any exposure creates cancer risk
Compressor Station
Transco 130 - Comer,
GA
“Actual” emissions estimated using emissions factors
from the EPA
Pollutant
VOCs
Formaldehyde
Acetaldehyde
Acrolein
Methanol
Benzene
NOx
PM10
Emissions (tons/year)
396.5
182.3
25.65
25.69
8.206
6.423
4143.4
73.7
Emissions Estimates for
Compressor Station
NOx, CO, and total hydrocarbon (THC) emissions
based on testing done in the early 1990’s.
VOC component of the THC estimated by EPA
database, approximated at 9.31%
The “actual” emissions for specific VOCs then
estimated using the EPA AP-42 emissions factors
Emissions Estimates for
Compressor Station
NOx, CO, and total hydrocarbon (THC) emissions
subject to uncertainty
Testing is ~15 years old
No information regarding overhaul status or age of equipment at testing vs.
current performance
VOCs not tested directly
EPA’s SPECIATE database is subject to uncertainty in converting THC to
VOCs
AP-42 Emissions factors used to get individual VOC emissions is limited and
may significantly underestimate actual emissions
Compressor Age at
Transco Station 130
Compressors and Manufacture or Reconstruction Date
Mainline Unit 1
1951
Mainline Unit 10
1958
Mainline Unit 2
1951
Mainline Unit 11
1959
Mainline Unit 3
1951
Mainline Unit 12
1962
Mainline Unit 4
1951
Mainline Unit 13
1962
Mainline Unit 5
1951
Mainline Unit 14
1968
Mainline Unit 6
1951
Mainline Unit 15
1969
Mainline Unit 7
1951
Mainline Unit 16
1971
Mainline Unit 8
1951
Mainline Unit 17
1980
Mainline Unit 9
1951
Mainline Unit 18
1990
AP-42 and Uncertainty
Canadian study looked at emission from a petroleum
refinery
Direct testing of emissions using laser based “DIAL” testing
Generated an emissions inventory for facility operations and compared to
inventory based on AP-42 estimates
DIAL measurements showed actual VOC emissions almost 15X AP-42
estimates
Dial measurements showed actual benzene emissions 18X AP-42 estimates
Emissions vs. Exposure
Emissions estimates in tons/year need to be
translated into concentrations such as ppm, ppb, or
ug/m3
This is typically done using an air disperson model
Air Dispersion Modeling
Resulting model is only as good as the inputs,
remember, garbage in equals garbage out
The emission rates of the pollutants of concern are
the most important inputs to the model for its
accuracy
Also dependent on climatological variables, wind
speeds and direction, temperatures, and pressures
What We Don’t Know
About the Health Risk
Uncertainty in actual emissions from facility
AP-42 may significantly underestimate or mischaracterize the actual
emissions
Transco test data may not be representative of current emissions
TPH emissions may not be accurately represented by the EPA database
No estimates of exposure or dose information from an
air dispersion model or equivalent
No understanding of individual susceptibilities
downwind of the station
No appreciable understanding of synergistic or
compound risk from multiple exposures
What We DO Know
About the Health Risk
Cancer risk begins even at low exposures
Cancer risk for children is estimated at 10-100X the risk
for adults at the same exposure
Respiratory and other effects of exposure to these
VOCs may occur at low exposures (e.g. formaldehyde
effects in FEMA trailers)
Formaldehyde, acetaldehyde, and benzene
(carcinogens or reasonably anticipated to be) are
released in significant quantities
PM and greenhouse gases present both regional and
global health risks
Is There a Serious
Health Risk?
There certainly is some risk based on what is known.
How serious is that risk?
We need a better understanding of the
uncertainties that we have identified before we can
qualify or quantify the risk
Should start with improving our understanding of
the actual emissions rates
And then use these inputs in an air dispersion
model
Without Knowing What
the Risk Is...
The surrounding public should not be subjected to the
industry’s experiment - the industry should bear the
burden of showing that there is no risk.
Currently regulations require almost no control on these
emissions - permits merely report emissions
older and higher polluting equipment is effectively grandfathered - similar to
coal-fired power plants
Significant improvements in emissions could be
achieved by installing new compressors and:
Selective Catalytic Reduction (SCRs) - to reduce NOx emissions
Catalytic oxidation equipment to reduce carbon monoxide emissions (yielding
more CO2 however)
Conclusions
Hazardous emissions from compressor stations have
been largely overlooked by current regulations
Regulatory programs must be improved to address the
“loophole”
Short of regulatory programs, pipeline operators should
take steps to minimize the threat to neighboring
populations as well as the regional and global
environment by:
better understanding emissions and associated risks
upgrading to modern compressors with control equipment
increasing the use of engineering controls, such as enclosing compressor
facilities and treating or scrubbing compressor emissions