Found info for my state. Need to check town next. I am copying the info below. Other folks from Mass might find it useful, but it's long, so skip it if you don't care.
Taken from:
http://www.mass.gov/dep/air/community/burnwood.htm#owfb
Given the high costs of oil and natural gas, a growing number of people in Massachusetts and elsewhere across the country are looking at outdoor hydronic heaters (wood-fired boilers) as potential money-saving solutions for heating their homes. These units are typically located outside the buildings they heat in small, insulated sheds with short smokestacks (usually no more than six to ten feet tall). They burn wood to heat water that is piped underground to provide heat and hot water to occupied buildings.
Outdoor wood-fired boilers can be substantially dirtier and less efficient than other home heating technologies. An investigation by the New York State Attorney General's Environmental Protection Bureau found that even when used properly, one of these units can emit as much fine particle pollution as:
* 2 heavy-duty diesel trucks
* 12 EPA-certified indoor wood stoves
* 45 passenger cars
* 1,000 homes with oil heat
* 1,800 homes with natural gas heat
NESCAUM, the Clean Air Association of the Northeast States, has also completed an Assessment of Outdoor Wood-Fired Boilers.
With their large, smoldering fires and short smokestacks, outdoor wood boilers create heavy smoke and release it close to the ground, where it lingers and exposes everyone in the area to nuisance conditions and health risks. Although these units are designed to burn dry, seasoned wood, some people use them to burn green wood, which generates much more smoke, and even household trash or construction debris, which not only can release a harmful array of chemicals but is also against state law.
The U.S. Environmental Protection Agency (EPA) has established a voluntary program that encourages manufacturers of outdoor wood-fired boilers to develop and distribute cleaner-burning and more efficient units. EPA issues a consumer label for any model that is submitted for testing and pollutes 70 percent less (Phase 1 "orange tag") or 90 percent less (Phase 2 "white tag") than less efficient units.
Under MassDEP regulations issued in December 2008:
* Only those outdoor hydronic heaters that are EPA Phase 2 "white tag" qualified and whose manufacturers have filed compliance certifications with MassDEP may be sold for installation in Massachusetts. See a list of currently certified units.
* New units must be located minimum distances away from property lines and neighbors' dwellings (determined by their heat output ratings and specific uses), meet minimum smokestack height requirements, burn only clean seasoned wood, and cause no nuisances or conditions of air pollution.
* Existing units (those in operation before December 26, 2008) are not required to be EPA Phase 2 "white tag" qualified, but like new units are subject to minimum smokestack height requirements, must burn only clean seasoned wood, and may not cause nuisances or conditions of air pollution.
Along with MassDEP, towns and cities - through their building, health, police and fire departments - are authorized to enforce specific provisions of the outdoor hydronic heater regulation. Some municipalities have enacted by-laws or ordinances that prohibit or limit the use of outdoor wood-fired boilers.
Even when units are operated according to manufacturers' instructions, they can sometimes create nuisance conditions that are prohibited by state air quality regulations. MassDEP and local boards of health have taken enforcement actions against people who own and operate units that have caused excessive odor or smoke. Regardless of how much a unit might have cost to install, sometimes the only way to resolve the nuisance conditions an outdoor wood boiler creates is to stop using it permanently.
If you are thinking about buying an outdoor wood-fired boiler, first check to be sure it is legal to install and operate one in your community, and if so, whether there are any specific restrictions you need to know about. Second, consider the impacts an outdoor wood-fired boiler could have on your neighbors and their property. Finally, if you do purchase a unit, never use it to burn anything other than dry firewood, and to the extent you can, operate it only during the cold weather months.