Evaluation of VOC Definition
Based on Vapor Pressure
Nicolas Peterson
EMAssist, Inc
nicolas.peterson@hill.af.mil
801-586-2494
Joint Services Environmental Management
Conference & Exposition
2005
Introduction



Volatile Organic Compounds (VOC) are extensively
regulated.
Generally, VOC are either exempt or not exempt.
Not all VOC are created equal, but they are
typically regulated as such.


Some are less volatile.
Some are less reactive.
When is an organic compound no longer volatile?

The EPA is currently re-examining how VOC are
regulated.
Overview
 Benefits
of updating VOC definition and/or
regulation
 VOC
definitions and regulations
 Suggested
 Recent
approach
EPA actions
 Conclusions
Benefits of Modifying Approach to VOC

Less burdensome regulations for “VOC” that are
minimally volatile and/or reactive (i.e. have
minimal ability to produce smog):



Focuses resources where they have more impact.
Reduces risk of non-compliance without impacting
the environment.
Encourages the use of “greener” materials.
Scientific Definition of Vapor Pressure
Surrounding atmosphere
@760mm Hg (1 atm)
Vapor Pressure
(Pvap)
High energy molecules
escaping to the
surrounding atmosphere
Liquid at temperature (T)
Vapor Pressure and Temperature
Vapor Pressure of Select Liquids
Vapor Pressure (mmHg)
450
400
2-propanol (IPA)
Methyl Ethyl Keytone (MEK)
H2O
Hexane
Methyl Isobutyl Keytone (MIBK)
350
300
250
200
150
100
50
0
0
5
10
15
20
25
30
Temperature ( oC)
35
40
45
50
Regulatory Definition of VOC

The EPA has defined a Volatile Organic Compound
(VOC) as any compound of Carbon that
participates in atmospheric photochemical
reactions excluding the few listed as “Exempt
VOC” by this section. [40 CFR 51.100(s)(1)].

No quantitative definition or lower-limit for
“volatile” is provided; however,



Disjointed approaches exist regarding this.
Sampling and test methods do have limitations.
Industry standards are typically used in the absence
of regulatory specifics.
Regulatory Definition of Semi-VOC

Semi-Volatile Organic Compounds (semi-VOC)
have been quantitatively defined as a subset of
the aforementioned VOC compounds whose
atmospheric boiling point is >100oC.

This definition has not been incorporated into the
regulations governing VOC.
California Air Resources Board (CARB) Definition of
Low Vapor Pressure VOC

The California Code of Regulations contains the
definition of Low Vapor Pressure VOC “LVP-VOC”:

A chemical “compound” or “mixture” containing at
least one Carbon atom and one of the following:
• Vapor pressure <0.1 mm Hg @ 20oC, or,
• Composed of chemical compounds with more than
12 Carbon atoms, or
• A boiling point >216oC.

LVP-VOC are exempt from the VOC Content Limits
for consumer products.
National VOC Emission Standards for Consumer
Products

Criteria for VOC Exemption:



Vapor pressure <0.1 mm Hg @ 20oC; or,
Consists of more than 12 Carbon atoms; or
A melting point higher than 20oC (and does not
sublimate).
Aerospace National Emissions Standards for
Hazardous Air Pollutants (NESHAP)

Solvents exempt from VOC Housekeeping
requirements:



Vapor Pressure <7 mm Hg @ 20oC; and,
Must not contain HAP.
This was set to encourage sources to use less
volatile solvents.
De Nevers’ VOC Definition

According to Dr. Noel De Nevers’, “Air Pollution
Control Engineering” VOC are those organic
liquids or solids whose room temperature (20oC)
vapor pressures are greater than about 0.52 mm
Hg, and;


Whose atmospheric boiling points are up to about
260oC, or,
Most compounds with less than about 12 Carbon
atoms.
EPA Test Methods

EPA test methods in 40 CFR 60, Appendix A are
used for measuring VOC when determining
compliance with emission limits.

Test methods for VOC sampling and analysis have
inherent limits in what compounds they can
capture and detect.
EPA Test Methods

EPA Methods 8260 and 8270 use either a Volatile
Organic Sampling Train (VOST) or Tedlar Bags to
collect the sample for analysis.


The Semi-VOST will not capture compounds with a
boiling point >200oC. (for Semi-VOC).
The Tedlar Bags and VOST will not capture
compounds with a boiling point >121oC.

Semi-VOST – Sampling Method 0010.

VOST – Sampling Methods 0030 and 0031.

Tedlar Bags – Sampling Method 0040.
EPA VOC Emissions Report to Congress
 EPA
VOC Emissions Report to Congress (March
1995) categorized certain VOC as “not reportable”
where the VOC:
 Were
solids,
 Had a vapor pressure <0.1 mm Hg @ 20oC, or
 Had > 12 carbon atoms.
Compilation of Reference Material

Considering regulatory definitions, requirements,
EPA Methods, etc., regarding Low Volatility VOC
(LV-VOC) together suggests:



A commonality among physical parameters.
Further definition and integration within rules would
be useful and appropriate.
Regulations should take into account “how” the LVVOC are used (e.g. heated).
Boiling
Point
# Carbon
Atoms
Vapor
Pressure
Low Volatility VOC

Suggest LV-VOC be defined as those organic
compounds that meet any one of the following:



Vapor pressure <0.1 mm Hg @ 20oC,
Boiling point >216oC (at 1 atm), or
Contain more than 12 Carbon atoms.

Suggested LV-VOC parameters are beyond noted
method detection limits (boiling point >216oC vs
121oC or 200oC).

Examples: Breakthrough, PD680 Type III, etc.
Low Volatility VOC

LV-VOC criteria were suggested based on:






EPA test methods
Academic reference
CARB definition of LVP-VOC
Consumer Products VOC Emission Standards
EPA’s 1995 VOC Emissions Report to Congress
Aerospace NESHAP treatment of solvents
Comparison of Parameters and Definitions
LOW - VOLATILITY VOC DEFINITION
Citation, Authority or Rule
Vapor
Pressure
mm Hg
@ 20C
Boiling
Point
(C)
#
Carbon
Atoms
Other
Context/Technology
Must not
contain HAP
Exempt from
Housekeeping req’ts
40 CFR 63.744 - Aerospace NESHAP
<7
"Air Pollution Control Engineering",
De Nevers
<0.52
>260
>12
Heuristic
CA Code of Regulations Section
94510(d) - CARB Consumer Products
<0.1
>216
>12
Exempt from VOC
content limits.
40 CFR 59.203(f) - Consumer
Products
<0.1
>12
melting pt
>20C
Exempt from VOC
content limits.
EPA’s VOC Emissions Report to
Congress (March 1995)
<0.1
>12
For solids,
N/A
Emission Inventory
Reporting.
EPA Test Method 0040 (for 8260b
&/or 8270c) - Tedlar Bag
>121
Sampling limit
EPA Test Method 0030 & 0031 (for
8260b &/or 8270c) – VOST
>121
Sampling limit
EPA Test Method 0010 (for 8260b
&/or 8270c) – Semi-VOST
>200
Sampling limit
LV-VOC
<0.1
>216
>12
Suggested criteria
Recent EPA Action

The EPA is currently exploring alternative
definitions/classifications to their VOC definition.

The EPA noted plans to publish a notice inviting
public comment on the VOC exemption policy.
[Federal Register: Sep 3, 2003]

The EPA proposed updating the VOC definition for
Aerosol Coatings to include California’s new,
reactivity-based VOC definition. [Federal Register:
Jan 7, 2005]
Reactivity-Based Definition of VOC

Specific VOC are given a numerical reactivity
value.

Values are relative and based on laboratory testing
that determines grams of ozone formed per gram
of organic compound reacted.

These relative reactivities are determined for a
number of specific compounds to make up the
Maximum Incremental Reactivity (MIR) Scale.
Reactivity-Based Definition of VOC

The new definition targets VOC on a reactivity basis
instead of the original “Exempt or Not” approach.

Applies to Aerosol Coating products in California.

Intended to encourage Manufacturers to reformulate
their Aerosol Coatings to use “greener” or less reactive
VOC.

Shows EPA’s willingness to consider new approaches
to classifying VOC based on their propensity to form
ozone.
Conclusions

Benefits of classifying certain VOC as LV-VOC



Allows for resources to be focused on more
important contributors to photochemical smog (i.e.
VOC that actually get into the air and react).
Allows for a reduction in the compliance burden for
air sources that really aren’t contributing to smog
formation.
Provides incentive to use “greener” (less reactive,
less volatile) VOC.
Conclusions

What we hope to accomplish with this
presentation:


Broaden awareness, and
Stimulate discussion among and between the
regulated and regulatory communities pertaining
to:
• Management practices
• Rule development
• Permit negotiations
Questions?