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1. Emissions Sources 2. Air Permits 3. Emissions and Calculations
4. Process Emissions 5. Types of Emission Controls
6. Key Questions for Air Emissions 7. Risk Management Plans
1. Emissions Sources / General
Sources of air pollutant emissions are: boilers, engines, or any kind of fuel-burning device (including your fireplace, wood stove, gas grill, car, lawnmower and Harley). They may be large or small, and may or may not have a chimney or stack. Large fuel burning sources generally need a stack so they don't cause a inhalation exposure problem near ground level.
Sources of air pollutant emissions are also any manufacturing processes that emit some portion of the materials used in the process (including grinding, welding, painting, coating, plating, spraying, rolling, heating, drying) to the atmosphere through through a vent, hood or stack on the wall or the roof of a facility.
The materials used in some manufacturing processes require emission control devices to cut down the emitted air pollutants to levels required by regulations or permits. These devices range from simple mechanical collectors for particulate matter, to complicated gas scrubbing systems and thermal or catalytic incinerators for volatile organic compounds.
In general, very small fuel-burning sources are not covered by Connecticut air regulations. These are:
- Boilers, furnaces and other space heaters with a liquid fuel burning capacity of less than 5 million British Thermal Units per hour (MMBTU/hr). A BTU is a unit of heat energy: burning one matchstick completely produces about one BTU. MM means a thousand times a thousand (i.e, one million). A fuel consumption rate equivalent to 5 MMBTU/hr is about 35 gal/hr (of #2 heating oil, it varies somewhat for other liquid fuels). A typical house furnace rating is about 0.1 MMBTU/hr.
- Boilers, furnaces and other space heaters with a gas fuel burning capacity of less than 11 MMBTU/hr. A natural gas consumption rate equivalent to 5 MMBTU/hr is about 5000 cubic feet (cf) per hour. A propane consumption rate equivalent to 5 MMBTU/hr is about 2000 cf/hr.
- Engines (such as emergency electrical generators or fire pumps) less than about 57 horsepower or 37 kilowatts.
Manufacturing processes also may not be covered by Connecticut air regulations if they are below a 5 ton/yr threshold for potential emissions of these air pollutants: particulate matter, sulfur dioxide, nitrogen oxides, volatile organic compounds, carbon monoxide.
Potential emissions are the emissions produced if the process or device runs at its maximum rated capacity for the entire year. For example, your car engine may be rated at 200 hp. You don't run it at that maximum power unless you're passing and going uphill; most of the time you use just a fraction of that available power . Nonetheless, the engine has the potential to run at that power level. It also has the potential to run constantly for an entire year (8760 hrs), but even soccer moms don't drive that much. So the potential gasoline consumption for this example would be about 105,000 gal/yr, costing about $140,000/yr. Of course, your actual gasoline consumption is probably more like 500 to 1,000 gal/yr. Note that -- unlike cars -- some manufacturing processes are designed to run at maximum rated capacity on a continuous basis (for example, stationary turbine engines producing electrical power). Generally, the regulations require you to determine permit applicability first on the basis of potential emissions, and second on actual emissions.
Very small manufacturing processes may be below the 5 ton/yr potential emission threshold for the criteria air pollutants, but they still could be covered by Connecticut air regulations if they emit a hazardous air pollutant. These chemicals are subject to special regulations that limit the concentrations in a stack or vent (called maximum allowable stack concentrations, or MASCs) to a level that is safe for human exposure at the facility's closest property line.
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2. Types of Air Permits
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In many cases where the potential emissions makes a facility a major source subject to Title V permitting, but the actual emissions are below the Title V thresholds, the facility can apply for a general permit by demonstrating the ability to continuously stay under the thresholds. There are a number of different ways to do this, and they are worth exploring as an alternative to a Title V permit.
Federal HAPs are 189 compounds listed by the Clean Air Act Amendments, and regulated by EPA. Connecticut has a different set of HAPs (although they overlap the federal) in three tables in the state regulations RCSA 22a-174-29:
- Table 1: known and probable carcinogens (73);
- Table 2: possible carcinogens and acutely hazardous compounds (145); and
- Table 3: chronically hazardous compounds (629).
The Connecticut HAPs are subject to special regulations that limit their concentrations in a stack or vent (called maximum allowable stack concentration, or MASC) to a level that is safe for human exposure after the wind carries emissions from the stack to the facility's closest property line. The federal HAPs are just triggers for Title V applicability, and don't relate to MASCs.
For a brief description of all air permits, go to theConnecticut Licensing Info Center, and search the Environmental category for the keyword Air. To get more detailed information, fact sheets and downloadable permit application forms, go to the DEP User's Guide to Environmental Permits.
2a. Federal Hazardous Air Pollutants (HAPs)
Chemical NameandCAS Number
Acetaldehyde --- 75070
Acetamide --- 60355
Acetonitrile --- 75058
Acetophenone --- 98862
2-Acetylaminofluorene --- 53963
Acrolein --- 107028
Acrylamide --- 79061
Acrylic acid --- 79107
Acrylonitrile --- 107131
Allyl chloride --- 107051
4-Aminobiphenyl --- 92671
Aniline --- 62533
o-Anisidine --- 90040
Asbestos --- 1332214
Benzene (including benzene from gasoline) --- 71432
Benzidine --- 92875
Benzotrichloride --- 98077
Benzyl chloride --- 100447
Biphenyl --- 92524
Bis (2-ethylhexyl) phthalate (DEHP) --- 117817
Bis (chloromethyl) ether --- 542881
Bromoform --- 75252
1,3-Butadiene --- 106990
Calcium cyanamide --- 156627
Caprolactam --- 105602
Captan --- 133062
Carbaryl --- 63252
Carbon disulfide --- 75150
Carbon tetrachloride --- 56235
Carbonyl sulfide --- 463581
Catechol --- 120809
Chloramben --- 133904
Chlordane --- 57749
Chlorine --- 7782505
Chloroacetic acid --- 79118
2-Chloroacetophenone --- 532274
Chlorobenzene --- 108907
Chlorobenzilate --- 510156
Chloroform --- 67663
Chloromethyl methyl ether --- 107302
Chloroprene --- 126998
Cresylic acid --- 1319773
o-Cresol --- 95487
m-Cresol --- 108394
p-Cresol --- 106445
Cumene --- 98828
2,4-D, salts and esters --- 94757
DDE --- 3547044
Diazomethane --- 334883
Dibenzofurans --- 132649
1,2-Dibromo-3-chloropropane --- 96128
Dibutylphthalate --- 84742
1,4-Dichlorobenzene (p) --- 106467
3,3-Dichlorobenzidene --- 91941
Dichloroethyl ether --- 111444
1,3-Dichloropropene --- 542756
Dichlorvos --- 62737
Diethanolamine --- 111422
N,N-Diethyl aniline (N,N-Dimethylaniline) --- 121697
Diethyl sulfate --- 64675
3,3-Dimethoxybenzidine --- 119904
Dimethyl aminoazobenzene --- 60117
3,3-Dimethyl benzidine --- 119937
Dimethyl carbomoyl chloride --- 79447
Dimethyl formamide --- 68122
1,1-Dimethyl hydrazine --- 57147
Dimethyl phthalate --- 131113
Dimethyl sulfate --- 77781
4,6-Dinitro-o-cresol, and salts --- 534521
2,4,-Dinitrophenol --- 51285
2,4-Dinitrotoluene --- 121142
1,4-Dioxane (1,4-Diethyleneoxide) --- 123911
1,2-Diphenylhydrazine --- 122667
Epichlorohydrin (1,Chloro-2,3-epoxypropane) --- 106898
1,2-Epoxybutane --- 106887
Ethyl acrylate --- 140885
Ethyl benzene --- 100414
Ethyl carbamate (Urethane) --- 51796
Ethyl chloride (Chloroethane) --- 75003
Ethylene dibromide (Dibromethane) --- 106934
Ethylene dichloride (1,2-Dichloroethane) --- 107062
Ethylene glycol --- 107211
Ethylene imine (Aziridine) --- 151564
Ethylene oxide --- 75218
Ethylene thiourea --- 96457
Ethylidene dichloride (1,1-Dichloroethane) --- 75343
Formaldehyde --- 50000
Heptachlor --- 76448
Hexachlorobenzene --- 118741
Hexachlorobutadiene --- 87683
Hexachlorocyclopentadiene --- 77474
Hexachloroethane --- 67721
Hexamethylene-1,6-diisocyanate --- 822060
Hexamethylphosphoramide --- 680319
Hexane --- 110543
Hydrazine --- 302012
Hydrochloric acid --- 7647010
Hydrogen fluoride (Hydrofluoric acid) --- 7664393
Hydroquinone --- 123319
Isophorone --- 78591
Lindane (all isomers) --- 58899
Maleic anhydride --- 108316
Methanol --- 67561
Methoxychlor --- 72435
Methyl bromide (Bromomethane) --- 74839
Methyl chloride (Chloromethane) --- 74873
Methyl chloroform (1,1,1-Trichloroethane) --- 71556
Methyl ethyl ketone (2-Butanone) --- 78933
Methyl hydrazine --- 60344
Methyl iodide (Iodomethane) --- 74884
Methyl isobutyl ketone (Hexone) --- 108101
Methyl isocyanate --- 624839
Methyl methacrylate --- 80626
Methyl tert butyl ether --- 1634044
4,4-Methylene bis (2-chloroaniline) --- 101144
Methylene chloride (Dichloromethane) --- 75092
Methylene diphenyl diisocyanate (MDI) --- 101688
4,4-Methylenedianiline --- 101779
Napthalene --- 91203
Nitrobenzene --- 98953
4-Nitrobiphenyl --- 92933
4-Nitrophenol --- 100027
2-Nitropropane --- 79469
N-Nitroso-N-methylurea --- 684935
N-Nitrosodimethylamine --- 62759
N-Nitrosomorpholine --- 59892
Parathion --- 56382
Pentachloronitrobenzene (Quintobenzene) --- 82688
Pentachlorophenol --- 87865
Phenol --- 108952
p-Phenylenediamine --- 106503
Phosgene --- 75445
Phosphine --- 7803512
Phosphorus --- 7723140
Phthalic anhydride --- 85449
Polychlorinated biphenyls (Aroclors) --- 1336363
1,3-Propane sultone --- 1120714
beta-Propiolactone --- 57578
Propionaldehyde --- 123386
Propoxur (Baygon) --- 114261
Propylene dichloride (1,2-Dichloropropane) --- 78875
Propylene oxide --- 75569
1,2-Propylenimine (2-Methyl aziridine) --- 75558
Quinoline --- 91225
Quinone --- 106514
Styrene --- 100425
Styrene oxide --- 96093
2,3,7,8-Tetraclorodienzo-p-dioxin --- 1746016
1,1,2,2-Tetrachloroethane --- 79345
Tetrachloroethylene (Perchloroehtylene) --- 127184
Titanium tetrachloride --- 7550450
Toluene --- 108883
2,4-Toluene diamine --- 95807
2,4-Toluene diisocyanate --- 584849
o-Toluidine --- 95534
Toxaphene (chlorinated camphene) --- 8001352
1,2,4-Trichlorobenzene --- 120821
1,1,2-Trichloroethane --- 79005
Trichloroethylene --- 79016
2,4,5-Trichlorophenol --- 95954
2,4,6-Trichlorophenol --- 88062
Triethylamine --- 121448
Trifluralin --- 1582098
2,2,4-Trimethylpentane --- 540841
Vinyl acetate --- 108054
Vinyl bromide --- 593602
Vinyl chloride --- 75014
Vinylidene chloride (1,1-Dichloroethylene) --- 75354
Xylenes (isomers and mixture) --- 1330207
o-Xylenes --- 95476
m-Xylenes --- 108383
p-Xylenes --- 106423
Antimony Compounds
Arsenic Compounds (inorganic including arsine)
Beryllium Compounds
Cadmium Compounds
Chromium Compounds
Cobalt Compounds
Coke Oven Emissions
Cyanide Compounds
Glycol Ethers
Lead Compounds
Manganese Compounds
Mercury Compounds
Fine Mineral Fibers
Nickel Compounds
Polycylic Organic Matter
Radionuclides (including radon)
Selenium Compounds
NOTE: For all listings above which contain the word "compounds" and for glycol ethers, the following applies: Unless otherwise specified, these listings are defined as including any unique chemical substance that contains the named chemical (i.e.,antimony, arsenic, etc.) as part that chemical's infrastructure.
For a fuller description, see Section 112 of the Clean Air Act Amendments.
3. Emissions and Calculations
Conceptually, calculating potential emissions from fuel burning sources is pretty simple:
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See the DEP permit instruction packages for some good examples of potential emissions calculations. The DEP materials provide conversion factors to get from a maximum fuel consumption rate to potential emissions of various pollutants. But sometimes the maximum fuel consumption rate is not listed on the nameplate of the device. If this is your situation, see the automated fuel use estimator for space heating boilers, and another fuel use estimator for engines; these will allow you to estimate maximum fuel use based on the energy specification on the nameplate.
Conceptually, calculating actual emissions from fuel burning sources is also pretty simple:
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Calculating actual and potential emissions from manufacturing processes can get pretty complex. The DEP downloadable permit instruction packages have some good examples of emissions calculations for the processes that they address. EPA publications have emission factors for many common industrial processes; some of these are downloadable documents in spreadsheet or word processor format, organized by process codes (called SCCs). In general, process emissions can be:
- Looked up by EPA SCC.
- Estimated by material usage, or by mass balance of material through the process.
- Directly measured by instruments or sampling media.
Air permits also generally require calculation of maximum allowable stack concentration (MASC) of any process emission that is a Connecticut hazardous air pollutant (HAP). This calculation is done by a formula that uses a published (in RCSA 22a-174-29 Tables 29-1, 29-2 and 29-3) hazard limiting value (HLV), the distance from the emission point to the property line, and the stack or vent exhaust rate. If the emission is from a tall stack, stack height also is used in the formula. The calculation process is pretty simple:
- Look at the Material Safety Data Sheets for all chemicals used (or generated) in the process, and determine if any are listed in the DEP HAP tables. If they are, write down their HLVs, using the 8-hr HLV if the process emission is continuous or the 30-min HLV if the emission is a short burst.
- Convert data to the proper units for the calculation: 3.28 ft = 1.0 m, and 2117 acfm = 1.0 m3/sec.
- Calculate the MASC per the formula, for each compound with a HLV. See the MASC diagram for the concept and the formulas (requires a calculator that can exponentiate).
The MASC has nothing to do with your actual emissions, it's just a cap that you can't go over. The next step is to calculate your maximum actual stack concentration (ASC) for each compound. This calculation is straightforward:
- Divide your maximum mass emission rate (e.g., lbs/hr) of each compound by the air flow of the exhaust system (e.g., the acfm rating found on the fan or blower nameplate or spec sheet). If you have some type of emission control device that reduces the mass emission rate, be sure to include that reduction.
- Convert the units used to be consistent with the calculated MASC: 1.0 lb = 456 g; 1 g = 1,000,000 ug; 2117 acfm = 1.0 m3/sec.
Compare the ASC to the MASC. If the ASC is above the MASC, you have a problem. There are a number of ways to resolve it, including reformulating to reduce use of the compound, relocating the stack or vent further from the property line, or installing emission controls.
4. Quantifying and Tracking Process Emissions
Conceptually, quantifying and tracking actual emissions from plant process sources is pretty simple:
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Conceptually, here's how it works for a large facility subject to a Title V permit:
A spreadsheet is frequently a handy way to manage the information. If your plant is complex, using many raw materials and many processes, then using commercial software may be worthwhile. In most emissions information systems, the bookkeeping to track material from purchase to emission to the atmosphere at large (Title V) facilities looks like this:
The DEP permit instruction packages have some good examples of calculations of actual emissions for the processes that they address. EPA publications haveemission factors for many common industrial processes; some of these are downloadable documents in spreadsheet or word processor format, organized by manufacturing process (called source classification codes, or SCCs).
5. Types of Emission Controls
The types of emission controls are as varied as the manufacturing processes they're designed for. In general, the controls reduce emissions of particulates (including small liquid aerosol droplets that behave like particles), gases (such as nitogen oxides, or volatile organic compounds), or odors.
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Some good sources of information about specific devices and technologies are:
- AWMA's Product Guide (Air & Waste Management Association)
- Croll-Reynolds (an equipment manufacturer)
- Midwest Air Products (an equipment manufacturer)
6. Key Questions for Air Emissions / Checklist
This link will open an Adobe pdf file to display a list of key questions to ask yourself on hazardous materials. (You need Adobe Acrobat Reader v3.0 or later enabled on your browser as a helper to view this list. To return to this page after viewing the list, just click the browser back button. If you don't have this free software, we suggest you download Acrobat Reader).
These questions are the most common starting questions for environmental auditing of small and mid-sized manufacturing facilities in Connecticut. Depending on your browser and platform, to print a paper copy of the questions you may need to first Save As a .pdf file on your hard drive.
7. Risk Management Plans and Clean Air Act Section 112(r)
There's a fair amount of confusion on this issue; specifically, on which companies have to prepare evaluations of the possibilities for accidental chemical releases, and prepare plans for dealing with offsite consequences of a release. An EPA regulation at 40 CFR 68 creates a requirement for such plans by June 21, 1999. Most small manufacturing companies in Connecticut are unlikely to be affected by this requirement. This diagram can help you decide:
To see the various lists of substances, go to the EPA regulations (Title 40) or OSHA regulations (Title 29) on their websites. In general, the substances covered by these regulations are chemicals that are pretty toxic, or that are very highly flammable. A few of the more common ones are chlorine gas, propane, and ammonia. These have to be present at the facility above threshold quantities, such as 10,000 lbs, to trigger the new requirement under 40 CFR 268.
There is a much fuzzier requirement, called a general duty clause, that could also apply to some facilities. This is found in Section 112(r)(1) of the Clean Air Act Amendments -- it's a law, not a regulation. The U.S. Senate, by some tortuous reverse logic, managed to define an extremely hazardous substance not by its physical or toxicological hazards, but (post facto) by whether or not it caused significant harm or property damage in an actual accident. So, you have to have a chemical accident to test this definition. Apart from the strange (and humorous) possibilities in this, it's probably always a good idea to review your existing emergency plan or procedures in an objective, "what-if" manner.
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