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Sustainability · Roaster

Roaster emissions

What leaves a coffee roastery through its stacks – smoke, volatile organic compounds, carbon monoxide, dust and chaff – where it comes from, why it rises late in the roast, how it is cleaned and how authorities regulate it.

Across the chain: Sustainability · Equipment

Source-checkedby Coffearium verification pass· Last source-checked 19 Oct 2026· Prepared with AI assistance· 13 sources (10 tier A)· Updated 19 Oct 2026
Reading depth
Contents
  • The United States Environmental Protection Agency (EPA) names particulate matter, volatile organic compounds, organic acids and combustion products as the main emissions of coffee roasting.1
  • The roaster is the main source of gaseous pollutants; coolers and green coffee handling add dust.1
  • Gas and volatile compounds in the off-gas rise strongly in the later part of the roast, depending on the roasting conditions.2,3,4
  • Roaster exhaust usually passes a cyclone, then a thermal or catalytic oxidiser that burns the organic compounds, at a cost in fuel.1,6,8
  • Swiss air pollution law has a provision of its own for coffee and cocoa roasteries; local US air districts set afterburner temperatures in their rules and permits.9,7,8

What a roaster emits#

A coffee roaster gives off more than heat. The United States Environmental Protection Agency (EPA) names four main groups of emissions: particulate matter, volatile organic compounds (VOCs), organic acids and combustion products.1 Particulate matter means fine solid particles and droplets in the air. VOCs are carbon compounds that evaporate easily; in roaster off-gas, part of them are coffee aroma compounds.4

Together, these make up the visible smoke and the smell around a roastery. A permit evaluation by a Californian air district describes the smoke and odour of roasting as the target of the afterburner.8 Swiss enforcement guidance expects that, as a rule, a roastery causes no excessive odour.10

Carbon monoxide and carbon dioxide also leave the roaster. They form in the beans during roasting and in the gas burner.1,2 According to a roasting textbook chapter, carbon dioxide is the main gas formed in the beans; carbon monoxide and nitrogen are other important ones.2

Where emissions arise#

The EPA calls the roaster the main source of gaseous pollutants.1 Its exhaust carries the gases and smoke, plus chaff: the silverskin that comes off the beans and is carried away with the air.2 A cyclone, a separator that spins solids out of the air, takes out the particles first.1,2 Chaff ends up in a chaff collector.8,12

The cooler is a second source. Its air flows through the hot beans after the drop,2 and the EPA lists coolers among the sources of particulate matter.1 Swiss guidance counts the capture of cooling air, as well as roaster off-gas, as part of the state of the art.10 Green coffee cleaning, handling and storage add dust, which the EPA lists with a fabric filter as control.1

Grinding and packing release gas too. Roasted coffee keeps giving off carbon monoxide and volatile compounds after roasting; the degassing entry covers that part.12,13

A · Roaster exhaust1RoasterSmoke, VOCs, CO, CO₂ 1 chaff 2 2CycloneRemoves particles 1 chaff to a collector 8 3OxidiserThermal 650–816 °C, 1 or catalytic, cooler 1 4StackCleaned gas; fuel addsCO₂ 1 chaff collectorLarge plants: a major part back to the burner,the rest vented, may pass cleaning 2 B · Cooling air6CoolerAir through thehot beans 2 7CycloneDust out 1 8CaptureSwiss guidance: cooling airis captured too 10 gas streamby-product or recirculated gasSchematic, not to scale. Small roasters usually have no recirculation.
Typical path of the exhaust in a roastery: roaster off-gas through a cyclone, optionally partly recirculated to the burner, then through a thermal or catalytic oxidiser to the stack; cooling air through its own cyclone.1,2,8,10 Schematic, not to scale.

Why emissions rise late in the roast#

Early in the roast, the beans mainly lose water. According to the roasting textbook chapter, the loss of organic matter only starts in the more advanced stages.2 In isothermal roasting, gas formation is low at first and speeds up strongly in the second half; it depends heavily on the roasting conditions.2

Measurements in roaster exhaust show the same pattern. A 2012 study sampled the off-gas of a 15–20 kg drum roaster. Volatile compounds stayed low for the first 500 s, then most of them rose strongly until the end.4 In a 2005 study, carbon dioxide in the exhaust rose sharply at the end of a fast roast, but stayed lower and levelled off in a slow one.3

The darker the roast, the more organic matter is turned into gas and volatile compounds.2 The textbook chapter describes the last stages of a roast as approaching the conditions of combustion.2 The second crack entry describes that phase and its smoke.

How roasteries clean the exhaust#

Cyclone first. Roaster exhaust usually passes a cyclone that removes particles.1 Chaff gathers in a chaff collector that has to be emptied and cleaned.8,12 The gas then goes to an oxidiser, often called an afterburner.1

Burning the smoke. A thermal oxidiser uses a burner to heat the exhaust until its organic compounds are destroyed.1,5 The EPA gives 650–816 °C as its typical operating temperature.1 A catalytic oxidiser does the same job at a lower temperature, with a catalyst such as platinum or palladium.1,6 Swiss guidance also names flameless regenerative oxidation and biofilters for odour.10

Recirculation. Small roasters usually draw in fresh air and release the hot exhaust at once.2 According to a roasting textbook chapter, most large plants lead a major part of the off-gas back to the burner.2 Another part must always leave and may pass a cleaning step.2

The energy cost. An afterburner needs fuel of its own. In one 2024 permit, the afterburner’s burner was rated at 88 kW (0.30 MMBtu/h), the roaster’s at 117 kW (0.40 MMBtu/h).8 Fuel drives the operating costs of thermal and catalytic oxidisers, according to the EPA.5,6 Burning fuel also adds carbon dioxide and can add carbon monoxide and nitrogen oxides.1,7

Rules and permits#

The rules opened for this entry target odour, smoke, organic compounds, dust and nitrogen oxides.7,8,10 They differ by country and, in the United States, by local air district.

Switzerland. The Ordinance on Air Pollution Control (Luftreinhalte-Verordnung, LRV) has a provision of its own for coffee and cocoa roasteries: Annex 2, No. 56.9 An execution aid by Cercl’Air, the Swiss society of air protection officers, explains how it is applied. It covers limits for dust, nitrogen oxides and total organic carbon, measurements and odour control.10

Germany. The Association of German Engineers (VDI) describes emissions and their control in roasted-coffee plants in guideline VDI 3892 (March 2015).11,2 It covers plants with a daily output of at least 0.5 tonnes.11

United States. Local air districts write emission controls into their rules and roaster permits. In California, the Sacramento district requires at least 90% VOC control for coffee roasters, by an afterburner or equivalent. A San Diego permit sets a minimum afterburner temperature.7,8 The Deep dive gives the values.

Reference values#

Values reported in the sources. Emission factors are US averages from limited tests; they are not measurements of any particular roaster. Conversions to kilograms per tonne are ours (1 lb per short ton = 0.5 kg per tonne).

Parameter Value reported Source
Roaster operating temperature 370–540 °C EPA AP-421
VOC (as methane), batch roaster, uncontrolled 0.86 lb per ton green coffee (≈0.43 kg/t); rating D EPA AP-421
VOC, batch roaster with thermal oxidiser 0.047 lb/ton (≈0.024 kg/t); rating D EPA AP-421
VOC, continuous roaster, uncontrolled / with thermal oxidiser 1.4 / 0.16 lb/ton (≈0.70 / 0.08 kg/t); rating D; the controlled value includes data from thermal catalytic oxidisers EPA AP-421
Particulate matter (filterable), continuous roaster, uncontrolled / with thermal oxidiser 0.66 / 0.092 lb/ton (≈0.33 / 0.046 kg/t); condensable 0.10 lb/ton with oxidiser; rating D EPA AP-421
Particulate matter (filterable), batch roaster with thermal oxidiser 0.12 lb/ton (≈0.06 kg/t); rating D EPA AP-421
Particulate matter, continuous cooler with cyclone 0.028 lb/ton (≈0.014 kg/t); rating D EPA AP-421
Particulate matter, green coffee screening, handling and storage with fabric filter 0.059 lb/ton (≈0.03 kg/t); rating E EPA AP-421
Carbon monoxide, continuous roaster, uncontrolled / with thermal oxidiser 1.5 / 0.098 lb/ton (≈0.75 / 0.049 kg/t); rating D EPA AP-421
Carbon dioxide, batch roaster, uncontrolled / with thermal oxidiser 180 / 530 lb/ton (≈90 / 265 kg/t); rating D EPA AP-421
Thermal oxidiser operating temperature Typically 650–816 °C EPA AP-421
Thermal destruction of most organic compounds 590–650 °C; design efficiencies 98–99.99% EPA fact sheet5
Catalytic oxidiser Inlet heated to ≈320–430 °C; ≈95% VOC destruction, 98–99% with more catalyst or higher temperature EPA fact sheet6
Off-gas recirculated in large plants A major part; another part must always be vented Roasting textbook chapter2
Afterburner, Sacramento permits (2019) VOC control ≥90%; ≥0.3 s at 1,200 °F (649 °C) below 110,000 Btu/h (≈32 kW), at ≥1,400 °F (760 °C) from 110,000 Btu/h to 3.5 MMBtu/h (≈32 kW–1 MW) SMAQMD BACT 141/1847
Catalytic afterburner, one San Diego permit (2024) Exhaust ≥950 °F (510 °C) from within 3 minutes of the start of each roasting cycle until its end; afterburner 0.30 MMBtu/h (≈88 kW), roaster burner 0.40 MMBtu/h (≈117 kW) SDAPCD evaluation8

Emission factors#

The EPA’s AP-42 compilation (section 9.13.2, September 1995) gives emission factors per ton of green coffee fed.1 Its ratings are mostly D, with single values at C or E; VOC is expressed as methane.1 AP-42 gives no factor for nitrogen oxides from coffee roasting, and no factors for destoners or for the equilibration of roasted coffee.1

00.20.40.60.8kg VOC per tonne green coffee (≈, from lb per short ton)Continuous roaster,uncontrolled≈0.70 (1.4 lb/ton)1 Continuous roaster,thermal oxidiser≈0.08 (0.16 lb/ton)1 Batch roaster,uncontrolled≈0.43 (0.86 lb/ton)1 Batch roaster, thermaloxidiser≈0.024 (0.047 lb/ton)1
Data table
kg VOC per tonne green coffee (≈, from lb per short ton)Source
Continuous roaster, uncontrolled≈0.70 (1.4 lb/ton)1
Continuous roaster, thermal oxidiser≈0.08 (0.16 lb/ton)1
Batch roaster, uncontrolled≈0.43 (0.86 lb/ton)1
Batch roaster, thermal oxidiser≈0.024 (0.047 lb/ton)1
Volatile organic compounds per tonne of green coffee, batch and continuous roasters with and without a thermal oxidiser, from EPA AP-42 emission factors (rating D); converted from lb per short ton. The continuous-roaster value with oxidiser includes catalytic units.1

Reading the factors. For a batch roaster, the VOC factor with a thermal oxidiser is about 5% of the factor without one; for a continuous roaster, about 11%.1 These ratios are our calculation from separate factors, not measured control efficiencies. Carbon dioxide runs the other way: the batch-roaster factor with an oxidiser (530 lb/ton) is higher than without (180 lb/ton).1 AP-42 expects carbon monoxide and carbon dioxide from fuel combustion, and an oxidiser burns fuel of its own.1,5

Where the solids go. Filterable particulate matter from a continuous roaster falls from 0.66 to 0.092 lb/ton with a thermal oxidiser; AP-42 also lists 0.10 lb/ton of condensable particulate matter after the oxidiser.1

Chemistry of the off-gas#

What is in it. The off-gas carries water vapour from drying, carbon dioxide, carbon monoxide and a wide range of VOCs.2,3,4 Diacetyl and 2,3-pentanedione, two alpha-diketones, are produced and released during roasting.12 Gas forms through pyrolysis and the Maillard reaction.2

Timing. In the 2012 study, the roaster off-gas was sampled online by proton transfer reaction time-of-flight mass spectrometry, on 15.6 kg batches of Guatemalan arabica coffee.4 VOC intensities were low until 500 s and rose strongly from then until the end of roasting; a change at about 730 s coincided with first crack.4 In the 2005 fluid-bed study, water vapour in the exhaust peaked and then declined, while carbon dioxide rose to the end of the fast roast.3 The authors suggest that the fast roast moved towards pyrolytic conditions at the end.3

Roast degree. According to the roasting textbook chapter, roast loss rises steadily during roasting, first through water and later through organic matter.2 Dark roasts lose more mass than light ones.2 Silverskin accounts for about 1% weight loss, depending on the green coffee.2,3 No study opened for this entry measured smoke or particulate emission rates across roast degrees on the same roaster.

Control technologies#

Cyclones. The EPA describes particulate removal by a cyclone before the oxidiser for roasters, and cyclones on coolers.1 One permit pairs the cyclone with a chaff collector and requires ducts and collector to be cleaned as often as needed to minimise build-up.8

Thermal oxidisers. AP-42 states a desired operating temperature of typically 650–816 °C.1 Separate oxidisers are preferred to the roaster’s own burner because they run hotter than most roasters.1 In the EPA’s general fact sheet, most organic compounds are destroyed at 590–650 °C; temperature, residence time, turbulence and oxygen all matter, and design efficiencies range from 98% to 99.99% and above.5 Its operating costs are relatively high because of the extra fuel.5

Catalytic oxidisers. AP-42 notes that thermal catalytic oxidisers need lower operating temperatures for the same control efficiency.1 The EPA’s catalytic fact sheet gives an inlet temperature of about 320–430 °C, about 95% VOC destruction for a typical unit and 98–99% with more catalyst or higher temperatures.6 Platinum and palladium are typical catalysts.6 Particulate matter can coat the catalyst and block it, and some elements, such as sulphur, can poison noble metal catalysts.6

200300400500600700800900°CRoaster operation (AP-42)370–5401 Catalytic oxidiser, gasheated to(fact sheet)≈320–4306 Thermal destruction ofmost organics(fact sheet)590–6505 Thermal oxidiser, typical(AP-42)650–8161 Catalytic afterburner, BayArea option, minimum≥288 (550 °F)7 Catalytic afterburner, SanDiego permit, minimum≥510 (950 °F)8 Afterburner, Sacramento,below ≈32 kW649 (1,200 °F), ≥0.3 s7 Afterburner, Sacramento,≈32 kW–1 MW, minimum≥760 (1,400 °F), ≥0.3 s7
Data table
°CSource
Roaster operation (AP-42)370–5401
Catalytic oxidiser, gas heated to (fact sheet)≈320–4306
Thermal destruction of most organics (fact sheet)590–6505
Thermal oxidiser, typical (AP-42)650–8161
Catalytic afterburner, Bay Area option, minimum≥288 (550 °F)7
Catalytic afterburner, San Diego permit, minimum≥510 (950 °F)8
Afterburner, Sacramento, below ≈32 kW649 (1,200 °F), ≥0.3 s7
Afterburner, Sacramento, ≈32 kW–1 MW, minimum≥760 (1,400 °F), ≥0.3 s7
Temperatures reported for roasting and for burning the off-gas: roaster operation and thermal oxidisers (EPA AP-42), thermal destruction of most organics and catalyst inlet (EPA fact sheets), and minimum afterburner temperatures in two Californian permits.1,5,6,7,8

Other methods. For spray dryers in soluble coffee plants, AP-42 describes a cyclone followed by a wet scrubber.1 For roasters in Sacramento, a baghouse (fabric filter) for particulate matter was judged not cost-effective.7 The Swiss execution aid names thermal post-combustion, flameless regenerative oxidation and biofilters for odour.10 No source opened for this entry describes electrostatic precipitators on coffee roasters.

Recirculation and energy. According to the roasting textbook chapter, open systems waste energy because the off-gas leaves hot.2 Recirculating plants send a major part back to the heating unit; the vented part keeps problematic, potentially explosive gas concentrations from building up.2 The chapter credits VDI 3892 with documenting progress in pollution control and energy efficiency.2 No source opened for this entry measured the fuel use of a roaster with and without an afterburner.

Regulation#

Rules as opened on 19 October 2026. They change; the legal text in force applies.

Switzerland (LRV). The consolidated LRV of 1 August 2026 lists, in Annex 2, No. 56 “Kaffee- und Kakao-Röstereien” (coffee and cocoa roasteries) among the special provisions for agriculture and food plants.9 The text of No. 56 could not be opened for this entry, so its limit values are not given here. The Cercl’Air execution aid (October 2016) sets out limits for total dust, nitrogen oxides and total organic carbon, the last stepped by roasting capacity.10 It requires an acceptance measurement and periodic functional checks for plants above a stated hourly raw-material throughput.10 According to the aid, odour can generally be reduced enough only by after-treatment, and small artisanal roasteries, generally not subject to No. 56, are also advised to install treatment because of odour.10 It notes that in the city of Zurich, older thermal post-combustion units did not remove roasting odour despite good measured values, and had to be upgraded.10

Germany (VDI 3892). The guideline’s March 2015 edition describes processes, emissions and their prevention and control as the state of the art.11 Its table of contents lists emission limits for dust, odour-intensive substances, total gaseous organic carbon and nitrogen oxides, and guidance on emission measurement.11 Only the description and contents were opened. Germany’s TA Luft (Technical Instructions on Air Quality Control) could not be opened for its coffee provisions.

United States. The two US documents opened are local regulation, valid only in their air districts. In its 2019 determination, the Sacramento district set best available control technology for coffee roasters in two sizes, by burner rating.7 Below 110,000 Btu/h (≈32 kW) it requires at least 90% VOC control by an afterburner with at least 0.3 s at 1,200 °F (649 °C), or equivalent.7 From 110,000 Btu/h to 3.5 MMBtu/h (≈32 kW to 1 MW) the same holds at 1,400 °F (760 °C) or more.7 For units of 325,000 Btu/h (≈95 kW) or more, nitrogen oxides are limited to 40 or 60 ppm at 3% oxygen for roaster burners, depending on burner temperature, and to 60 ppm for afterburners and oxidisers.7 The same document lists a catalytic afterburner at 550 °F (288 °C) or more as a feasible option in the Bay Area for roasters below 110,000 Btu/h.7

A 2024 San Diego evaluation for a roaster of about 279 kg/h (616 lb/h) with a catalytic afterburner requires an afterburner exhaust temperature of at least 950 °F (510 °C), reached within 3 minutes of the start of each roasting cycle and held until its end.8 It also requires the cyclone and afterburner to run whenever the roaster runs, a temperature gauge with records kept for three years, and cleaning of ducts and chaff collector as often as needed.8 Its visible-emission condition allows no more than 20% opacity (Ringelmann No. 1) for more than 3 minutes in any hour.8 The district based the roasting emissions on AP-42 factors.8

Exposure inside roasteries#

This section describes what authorities and studies report. It does not give safety advice.

One facility evaluated. In a NIOSH (National Institute for Occupational Safety and Health) evaluation of one US roasting and packaging plant, 31 of 37 full-shift samples exceeded the NIOSH recommended exposure limit for diacetyl of 5 ppb.12 Five of 37 exceeded the limit for 2,3-pentanedione of 9.3 ppb.12 Short-term diacetyl levels were higher during grinding, roasting and packaging; during roasting they reached up to 30.7 ppb.12 Carbon monoxide was higher during tasks near the roasters and grinders, and exceeded the NIOSH ceiling of 200 ppm for employees whose duties included roasting and grinding quality-control samples.12

Why the limits exist. NIOSH set its limits for diacetyl and 2,3-pentanedione to reduce the risk of decreased lung function and of obliterative bronchiolitis, a severe irreversible lung disease.12 Its short-term exposure limits are 25 ppb for diacetyl and 31 ppb for 2,3-pentanedione.12 Some employees reported that green coffee dust, chaff, ground coffee or smoke caused or aggravated eye and nose symptoms.12

What the evaluation recommended. Among its recommendations: carbon monoxide monitors near the roasters and grinders, local exhaust ventilation at all grinders, and respirators for voluntary use when cleaning chaff from the exhaust system.12 A 2022 emission study found diacetyl emission rising with roast degree in freshly roasted coffee, and both diketones rising as particles got finer.13 The degassing entry covers carbon monoxide from stored and ground coffee.

Risks and defects#

  • Odour. Swiss guidance expects no excessive odour and names after-treatment as generally the only sufficient way to reduce it.10
  • Visible smoke. One permit limits the opacity of visible emissions.8
  • Chaff build-up. In the plant NIOSH evaluated, the roasters were routinely cleaned of chaff that had accumulated in the exhaust lines.12 One permit requires ducts and chaff collector to be cleaned as often as needed to minimise build-up.8
  • Catalyst fouling. Particulate matter can coat a catalyst and reduce its effect.6
  • Gas accumulation. Recirculating systems must vent part of the off-gas to avoid potentially explosive concentrations.2
  • Worker exposure. Diketones and carbon monoxide near roasters and grinders exceeded NIOSH limits in one evaluated plant.12

Open questions#

  • Smoke and roast degree. No study opened for this entry measured particulate or VOC emission rates for light and dark roasts on the same roaster.
  • Small shop roasters. The AP-42 factors date from 1995 and rest on limited tests.1 No study opened for this entry measured emissions from roasters of a few kilograms per batch with and without afterburners.
  • Odour versus measured values. Swiss guidance reports older thermal units that met measured values but did not remove roasting odour.10 How odour relates to total organic carbon in roaster exhaust was not found in the sources opened.
  • Energy and climate. The fuel an afterburner adds per kilogram of coffee, and its share of a coffee’s carbon footprint, were not found in the sources opened.

Key studies#

Wieland et al., 2012 – Volatiles in roaster off-gas, second by second. Sampled the off-gas of a gas-fired 15–20 kg drum roaster online by proton transfer reaction mass spectrometry during roasts of Guatemalan arabica coffee. Volatile compounds stayed low for the first 500 s and then rose strongly to the end, and the signal was used to predict roast degree.

Analytical and Bioanalytical Chemistry 402, 2531–2543 · doi:10.1007/s00216-011-5401-9

Geiger et al., 2005 – Carbon dioxide and water in the exhaust. Measured carbon dioxide and water vapour in the exhaust of a fluid-bed laboratory roaster for a fast and a slow roast to equal colour. Carbon dioxide rose sharply at the end of the fast roast but levelled off in the slow one.

Journal of Food Science 70(2), E124–E130 · doi:10.1111/j.1365-2621.2005.tb07084.x

Harvey et al., 2018 – Exposures in a roasting and packaging plant. A NIOSH health hazard evaluation combined air sampling, real-time gas monitoring and a medical survey at one US facility. Most full-shift samples exceeded the diacetyl limit, and carbon monoxide peaks above the ceiling occurred during roasting and quality-control grinding.

NIOSH Health Hazard Evaluation Report 2016-0144-3305 · cdc.gov/niosh

LeBouf et al., 2022 – Diketone emission from roasted coffee. Measured specific emission rates of diacetyl and 2,3-pentanedione from light and dark coffee as whole beans, coarse and fine grounds, and used them to model worker exposure. Finer grinds emitted more, and diacetyl emission from freshly roasted coffee rose with roast degree.

Frontiers in Public Health 10, 786924 · doi:10.3389/fpubh.2022.786924

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Change log

  • – Removed the claim that chaff in the exhaust is a fire hazard and lowers efficiency (attributed to NIOSH) and the recommendation of periodic chaff cleaning "to reduce a fire hazard"; replaced by what the report says (routine cleaning of chaff from exhaust lines; respirators for voluntary use when cleaning chaff) and the San Diego permit's cleaning condition. Reason: Verification pass; NIOSH HHE 2016-0144-3305 does not mention fire or efficiency in connection with chaff.
  • – The textbook example of 80% off-gas recirculated and 20% vented removed from text, quick facts, table and diagram; now "a major part" and "another part must always be vented". Reason: Verification pass; number rule – the figures rest on one Tier B source (Folmer ed. 2017, ch. 11) only.
  • – AP-42 rating for green coffee screening, handling and storage with fabric filter corrected from D to E; VOC marked "as methane"; continuous-roaster controlled factors noted as including thermal catalytic oxidisers. Reason: Verification pass; AP-42 9.13.2 Table 9.13.2-1 footnote f and Table 9.13.2-2 footnotes b and k.
  • – San Diego afterburner condition corrected to 950 °F reached within 3 minutes of the start of each roasting cycle and held until its end; duct and chaff-collector cleaning "as often as needed" instead of "regular"; one permit, not "permits". Reason: Verification pass; SDAPCD engineering evaluation (28 August 2024), conditions 3 and 5.

Sources

  1. AU.S. Environmental Protection Agency (1995). AP-42, Fifth Edition, Section 9.13.2: Coffee Roasting. U.S. EPA, Compilation of Air Pollutant Emission Factors.
  2. BSchenker, S.; Rothgeb, T. (2017). The Roast – Creating the Beans' Signature. In: Folmer, B. (ed.), The Craft and Science of Coffee, Academic Press, ch. 11, pp. 245–271. doi:10.1016/B978-0-12-803520-7.00011-6 · other copies
  3. AGeiger, R.; Perren, R.; Kuenzli, R.; Escher, F. (2005). Carbon Dioxide Evolution and Moisture Evaporation During Roasting of Coffee Beans. Journal of Food Science 70(2), E124–E130. doi:10.1111/j.1365-2621.2005.tb07084.x · other copies
  4. AWieland, F.; Gloess, A. N.; Keller, M.; Wetzel, A.; Schenker, S.; Yeretzian, C. (2012). Online monitoring of coffee roasting by proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS): towards a real-time process control for a consistent roast profile. Analytical and Bioanalytical Chemistry 402, 2531–2543. doi:10.1007/s00216-011-5401-9 · other copies
  5. AU.S. Environmental Protection Agency Air Pollution Control Technology Fact Sheet: Thermal Incinerator (EPA-452/F-03-022). U.S. EPA, Clean Air Technology Center (no publication date on the document).
  6. AU.S. Environmental Protection Agency Air Pollution Control Technology Fact Sheet: Catalytic Incinerator (EPA-452/F-03-018). U.S. EPA, Clean Air Technology Center (no publication date on the document).
  7. ASacramento Metropolitan Air Quality Management District (SMAQMD) (2019). BACT Determination No. 141 and No. 184 – Coffee Roaster. SMAQMD, Sacramento, California (local regulation).
  8. ASan Diego County Air Pollution Control District (SDAPCD) (2024). Better Buzz 8345 AB3205 Eng Evaluation (engineering evaluation of a coffee roaster with catalytic afterburner). SDAPCD, San Diego, California (local regulation; permit evaluation signed 28 August 2024).
  9. ASchweizerischer Bundesrat (1985). Luftreinhalte-Verordnung (LRV) vom 16. Dezember 1985, SR 814.318.142.1. Swiss Confederation (consolidated version of 1 August 2026, via LexFind).
  10. BCercl'Air (2016). Recommandation No 31b, Fiches d'exécution « surveillance des émissions »: Torréfaction du café et du cacao. Cercl'Air, Swiss society of air protection officers (execution aid for the Ordinance on Air Pollution Control, OPair/LRV).
  11. A/BVerein Deutscher Ingenieure (VDI) (2015). VDI 3892 Emission control – Roasted-coffee-producing industry – Plants with a minimum daily output of at least 0,5 tonnes. VDI, Düsseldorf (standard page and table of contents; full text not opened).
  12. AHarvey, R. R.; Hawley, B.; Martin, S. B. (2018). Evaluation of exposures and respiratory health at a coffee roasting and packaging facility (Health Hazard Evaluation Report 2016-0144-3305). National Institute for Occupational Safety and Health (NIOSH), CDC, U.S. Department of Health and Human Services.
  13. ALeBouf, R. F.; Ranpara, A.; Fernandez, E.; Burns, D. A.; Fortner, A. R. (2022). Model Predictions of Occupational Exposures to Diacetyl and 2,3-Pentanedione Emitted From Roasted Whole Bean and Ground Coffee: Influence of Roast Level and Physical Form on Specific Emission Rates. Frontiers in Public Health 10, 786924. doi:10.3389/fpubh.2022.786924 · other copies

Tier A · authoritative · B · trade and expert · C · general. Supporting quotes for every source are in the data version of this entry. If a publisher’s site refuses access, try the doi link or “other copies”.

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