Contractors have a lot to worry about it. In addition to their customers needs, rising material costs and their own employees, they need to worry about subcontractors who they hire to help perform a job. A subcontractor is an individual, or in some cases a business, that signs a contract to perform part, or sometimes all, of the obligations of another’s contract.

Each year, more than 400 Americans die from unintentional CO poisoning, according to the Centers for Disease Control and Prevention (CDC). In addition, more than 20,000 visit the emergency room and more than 4,000 Americans are hospitalized due to CO poisoning.