Smoke consists of many gaseous components such as unburned solid particles, carbon monoxide, resinous particles, hydrocarbons, formaldehyde, acids, water, alcohols and many others. The final composition of smoke will vary depending on wood composition, humidity, smoke generation temperature, even the product type. The temperature control is probably the most effective factor in controlling the process. To control smoke emissions from large industrial smokehouses and to meet ever increasing pollution standards, new more effective methods have been devised:
- Afterburner is a secondary combustion heating device which creates high enough temperatures to burn most smoke components that would normally escape into the atmosphere. The device is placed on top of the smokehouse, between floors or on the roof of the building. Afterburner is an effective device but energy hungry which makes it costly to operate.
- Wet scrubber is a wet devices that try to capture smoke particles, mix them with water and drain them away. Mist scrubbers inject water mist into the chamber where they collide with smoke exhausting from the smoking chamber. Packed bed scrubbers are lined with a special wet material that absorbs smoke. Smoke liquefies and is drained away. Vortex scrubbers use a whirling flow pattern which breaks water into fog like droplets. Smoke mixes with droplets and then liquefies.
- Electrostatic precipitator is a filter that works on the same principle used in car catalytic converters. The exhausting smoke is first heated, then it passes through a catalyst, causing a chemical reaction that eliminates harmful emissions leaving CO2 and water. Precipitators are effective for controlling solid smoke particle emissions. Electrostatic precipitators are commonly used in restaurant hood filtering systems.
- Combined methods, such as a wet scrubber for gaseous emission control may be used with an electrostatic precipitator for particle removal. Needless to say all technologies are applied to smoke that is exiting the smoking chamber and not before.
All above methods are quite expensive to implement and it is not expected that a hobbyist will find much use for them. Nevertheless for those interested in starting a commercial enterprise this information might be of value. A smokehouse can be built or installed for a commercial purpose or for private use and depending on its location it will face different regulations. There is not much in the Code of Federal Regulations that covers the subject and the only federal institution that may come into play is the Environmental Protection Agency (EPA) as they deal with the problems of pollution. The Food Safety And Inspection Service does not care about the smoker, its location, size or the amount of smoke it discharges. They worry about factors which influence meat safety such as the plant’s sanitary conditions or processing temperatures.
What should be noted is that a store which smokes fish for retail sale will be subject to less stringent requirements than an establishment that smokes meats wholesale.
There are commercial stores where smoking meats takes place in a horizontal smoker outside and then they are brought inside of the store. The store itself conforms to the safety requirements such as plumbing, wash sinks, coolers, garbage disposal etc., of the local county. An insignificant amount of smoke is discharged and if there are no complaints from local businesses, the little store should be fine. Most smart operators start smoking at 5 AM and by 9 AM the bulk of production is done.
A commercial plant smoking thousands of pounds of meat an hour will definitely need to install a filtering system. The EPA document Compilation of Air Pollutant Emission Factors AP-42, Section 9.5.2, covers emission standards in Meat Smokehouses.
Every state or county will have a final word on its air pollution restrictions and local authorities should be consulted before construction is started. For example the following comes from California regulations:
Section 5 - List of Title V, Insignificant Activities
I. General Criteria for Insignificant Activities
An insignificant activity is any activity, process, or emission unit which is not subject to a source-specific requirement of a State Implementation Plan, preconstruction permit, or federal standard and which: 1) meets the “Criteria for Specific Source Categories” below; or 2) emits no more than 0.5 tons per year of a federal hazardous air pollutant (HAP) and no more than two tons per year of a regulated pollutant that is not HAP.
E. Food Processing Equipment
1. Any oven in a food processing operation where less than 1,000 pounds of product are produced per day of operation.
13.7 lb VOC/2,000 lb product * 1,000 lb product = 6.9 lb VOC/day
2. Any smokehouse in which the maximum horizontal inside cross section area does not exceed 20 square feet.
0.3 lb PM10/ton of meat * 1 ton/day = 0.3 lb PM10/day
0.6 lb CO/ton of meat * 1 ton/day = 0.6 lb CO/day
3. Any confection cooker, and associated venting or control equipment, cooking edible products intended for human consumption.
Insignificant air pollutant emissions from this source.
VOC = Volatile organic compound.
PM = Particulate matter.
CO = Carbon monoxide.
Federal standards include:
40 CFR Parts 60 (New Source Performance Standards), 61 (National Emission Standards for Hazardous Air Pollutants), 63 (National Emission Standards for Hazardous Air Pollutants for Source Categories). HAPs are toxic substances listed pursuant to Section 112 (b) of the Federal Clean Air Act.
A home made smoker can be a simple inexpensive unit, sometimes even portable and we may not even involve any officials. On the other hand if one intends to build an expensive combination island (grill, smoker, water sink, lights) that will require electrical wiring and gas and plumbing connections, it will be a good idea to find out from the local city hall about regulations.
In every state each county has a County Nuisance Ordinance. If someone finds that your campfire or open burning is a nuisance to him or her, you will be asked to put the fire out. That will apply to meat smoking as well. If you live in a metropolitan area and smoke meats for hours at the time, someone might call the officials.
The local Fire Department does not have much information about smokers or meat smoking, all they are concerned with is the common sense safety: keep fire away from any structures, don’t smoke under low hanging trees, have a garden hose (water source) close by, don’t use any flammable or combustible liquids, have adult supervision when the kids are present, make sure the fire is completely out after the event is over, etc.
If you plan to build a sophisticated smokehouse, by all means show the fire department the plans and they will gladly review them and make some recommendations. Without a doubt the first step is to talk to the Local Zoning Office to see whether such a structure is allowed and in most cases it is.
The second step is to check with your county city hall if a building permit is required. They will have everything there is to know about building a smokehouse in their area. For example, in Maryland the Air Quality General Permit to Construct “Charbroilers and Pit Barbecues” applies to every person who owns, constructs (installs), or operates a non-residential charbroiler or pit barbecue with a total cooking area greater than 5 square feet (0.46 square meters). The permit is not required for residential units.
In St. Louis City the smokehouses are permitted within residential zoning districts as long as they conform to city ordinances. Any building or structure intended to be used as a smokehouse within a residential zoning district which exceeds fifty (50) square feet in size shall require a permit from the building commissioner prior to construction and shall conform to all applicable regulatory codes for such structure (Ord. 65944 #2, 2003).
In the state of Milwaukee the General Building Code has Section 239-4 which says that: In addition to the regulations 239-1, Detached Private Garages, smokehouses shall:
- have walls of not less than 2 hours fire-resistive construction with a noncombustible floor and roof, and a metal door overlapping the door opening at least one inch at the top and on both sides, and shall have a noncombustible vent or smoke flue.
- may be located within the principal building if constructed of 3 hour fire-resistant construction throughout.
No matter where you are located you may expect requirements such as:
- Non-combustible or masonry wall structures.
- Metal door.
- Concrete slab (at least 3 1/2” thick).
- Minimum distance of 15’ from property lines and from any other structure.
- No sale of smoked meat that was prepared in a home smokehouse.
As you can see there isn’t any set of government instructions or regulations on building smokehouses and you have to do your own homework by visiting your local court house or city hall.