Fire departments and unions representing fire fighters have been publicizing the enormity of the potential impact (link here). A bipartisan group of Senators wrote the Department of Labor and IRS on Monday, December 16th, lobbying for non-coverage under the law, and a legal opinion is expected sometime in early 2014 before the employer mandate becomes effective. If volunteers are deemed to be employees, the fire departments will be required to offer health insurance or else face steep penalties. This would effectively bankrupt volunteer fire departments, which have tight budgets, and would be wasteful since most personnel likely have other jobs which offer benefits.
Since we all rely on fire protection, this is an important issue which should be followed closely.