We are subject to stringent and comprehensive federal, state and local environmental and worker health and safety laws and regulations governing, among other matters, the operation of fuel storage tanks, release of emissions from our vehicles (including engine idling) and facilities, the health and safety of our workers in conducting operations and adverse impacts to the environment. Under certain environmental laws, we could be subject to strict liability, without regard to fault or legality of conduct, for costs relating to contamination at we own or operate or previously owned or operated and at third-party sites where we disposed of waste, as well as costs associated with the clean-up of releases arising from accidents involving our vehicles. We often operate in industrial areas, where truck terminals and other industrial activities are located, and where soil, groundwater or other forms of environmental contamination have occurred from historical or recent releases and for which we may incur remedial or other environmental liabilities. We also maintain aboveground fuel storage tanks at some of our facilities and vehicle maintenance operations at certain of our facilities. Our operations involve the risks of fuel spillage or seepage into the environment, environmental damage and unauthorized hazardous material spills, releases or disposal actions, among others.
Increasing efforts to control air emissions, including greenhouse gases, may have an adverse effect on us. Federal and state lawmakers have implemented various climate change initiatives and greenhouse gas regulations and may implement additional initiatives in the future, all of which could increase the cost of new tractors, impair productivity and increase our operating expenses.
Compliance with environmental laws and regulations may also increase the price of our equipment and otherwise affect the economics of our business by requiring changes in operating practices or by influencing the demand for, or the costs of providing, transportation services. For example, regulations issued by the EPA and various state agencies that require progressive reductions in exhaust emissions from diesel engines have resulted in higher prices for tractors and diesel engines and increased operating and maintenance costs. Also, in order to reduce exhaust emissions, some states and municipalities have begun to restrict the locations and amount of time where diesel-powered tractors may idle. These restrictions could require us to alter our drivers' behavior, purchase on-board power units that do not require the engine to idle or face a decrease in productivity. We are also subject to potentially stringent rulemaking related to sustainability practices, including conservation of resources by decreasing fuel consumption. This increased focus on sustainability practices may result in new regulations and/or customer requirements that could adversely impact our business. Historically, our environmental compliance costs have not had a material adverse effect on our results of operations; however, there can be no assurance that such costs will not be material in the future or that future compliance will not have a material adverse effect on our business and operating results.
If we have operational spills or accidents or if we are found to be in violation of, or otherwise liable under, environmental or worker health or safety laws or regulations, we could incur significant costs and liabilities. Those costs and liabilities may include the assessment of sanctions, including administrative, civil and criminal penalties, the imposition of investigatory, remedial or corrective action obligations, the occurrence of delays in permitting or performance of projects, and the issuance of orders enjoining performance of some or all of our operations in a particular area. The occurrence of any one or more of these developments could have a material adverse effect on our results of operations, competitive position and financial condition. Environmental and worker health and safety laws are becoming increasingly more stringent and there can be no assurances that compliance with, or liabilities under, existing or future environmental and worker health or safety laws or regulations will not have a material adverse effect on our business, financial condition, results of operations, cash flows or prospects.