- Contact information
- For information on mobile sources, contact:
- Karen Walsh
Air management specialist
Vehicles - Mobile sources
Mobile sources include not only cars and trucks but also such "off-road" equipment as bulldozers, motor boats, locomotives, aircraft – even weed whackers. Emissions from these types of sources come not only from fuel combustion but also from fuel evaporating from containers and tanks during and afer the fueling process. Many different fuels are used in mobile sources, and some burn cleaner than others. The type of mobile source and the type of fuel it uses will be major factors in how that source affects the environment.
Vehicles and equipment
Highway vehicles include vehicles that are normally operated on roadways, including cars, trucks, buses and motorcycles. Off-road vehicles include a wide variety of equipment and engine types that are normally not operated on roadways. This includes vehicles and equipment used in construction, agriculture, aircraft, locomotive, marine, recreational, manufacturing and landscaping industries.
Diesel engines are used in applications such as construction, farming, locomotives and mining. Lawn and garden equipment such as lawn mowers, chainsaws, weed whackers and leaf blowers typically use gasoline powered engines. Off-road vehicles also include dirt bikes, all terrain vehicles (ATVs) and snowmobiles.
Mobile sources use many different fuels including gasoline, diesel and alternative. Gasoline comes from refined crude oil. Reformulated gasoline, known as RFG, is gas blended to burn cleaner by reducing smog-forming toxic pollutants. The Clean Air Act requires that RFG be used in cities with the worst smog pollution to reduce harmful emissions that cause ground-level ozone.
Diesel fuel also comes from refined crude oil. In 2007, all diesel powered highway vehicles were required to use ultra-low sulfur diesel fuel with an average sulfur content of 15 parts per million (ppm) to help reduce emissions. Off-road equipment is also required to use ultra-low sulfur fuel.
- Consumer Guide to E15 (AM-502) – This factsheet provides basic information about E15, a 15 percent ethanol fuel blend that may be available at gas stations in Wisconsin.
- Selling E15: Resources for Fuel Retailers (AM-516) – This factsheet lists resources that may be useful for gas station owners interested in selling E15, a 15 percent ethanol fuel blend. The Wisconsin DNR does not regulate E15 sales, but retailers must meet a number of federal requirements.
There are many toxic chemicals emitted from mobile sources and their associated fueling systems. The pollutants that are of most concern are acrolein, benzene, 1-3 butadiene, formaldehyde, acetaldehyde, and diesel PM. A recent study in California indicates that about 90% of the risk of cancer from air pollutions is associated with diesel PM. For more information, visit California's South Coast Air Quality Management District.
How mobile sources emissions affect air pollution
The type and amount of emissions from specific mobile sources depends on multiple factors, including the type of fuel being combusted and the age and efficiency of a vehicle. However, there are some general effects listed below.
Carbon monoxide (CO), which is produced by many mobile sources, can cause serious health problems because it reduces the amount of oxygen reaching the body's organs and tissues. More than 90 percent of the CO in the atmosphere results from incomplete combustion in mobile sources.
Ground level ozone is created by a reaction of volatile organic compounds (VOC) and nitrogen oxides (NOx) in the presence of heat and sunlight. Mobile sources are significant sources of these two principal precursor pollutants. In Wisconsin, mobile sources account for more than 40 percent of the manmade VOC emissions and more than 60% of the manmade NOx emissions.
These very small particles are created in atmospheric reactions, resulting from emissions of NOx, VOC, sulfur dioxide (SO2) and ammonia (NH4). In Wisconsin, mobile sources account for more than 40 percent of the man-made VOC emissions and more than 60 percent of the man-made NOx emissions. Gasoline powered cars may be a significant source of ammonia. Some recent research indicates that ammonia emissions from these vehicles are significantly underestimated.
How mobile source emissions affect human health
Mobile sources are implicated in creating adverse health effects from carbon monoxide, ground level ozone and fine-particles. The health effects include premature death, aggravated asthma, immune system depression, cardio-pulmonary problems and lost school and work days. Additionally, other toxic emissions from mobile sources are known to cause cancer along with creating respiratory problems.
Mobile sources are significant sources of CO2 (carbon dioxide), methane, N2O (nitrous oxide) and HFCs (hydrofluorocarbons). All four compounds are principal contributors to greenhouse gases and climate change, although, CO2 is by far the largest contributor. In Wisconsin, highway vehicles emit about 33 million tons of CO2 per year. Off-road equipment emit about 3 million tons of CO2 per year. For more information, visit EPA Climate Change
Visibility degradation, or haze, results from tiny particles in the atmosphere that diffuse light. The same pollutants mentioned above - NOx, VOC, SO2, and ammonia - which contribute to PM2.5 are also significant contributors to haze.
The vapor recovery requirements for gasoline dispensing facilities in Wisconsin have recently changed. While Stage I vapor recovery systems are still required in 20 counties, gas stations may now voluntarily remove or decommission the Stage II vapor recovery systems once required in nine counties. In addition, the DNR is administering a grant program to reimburse gas station owners for eligible costs of removing or decommissioning Stage II systems.
Vapor recovery requirements for gasoline dispensing facilities
Stage I requirements
Stage I vapor recovery systems are required in Brown, Calumet, Dane, Dodge, Door, Fond du Lac, Jefferson, Kenosha, Kewaunee, Manitowoc, Milwaukee, Outagamie, Ozaukee, Racine, Rock, Sheboygan, Walworth, Washington, Waukesha and Winnebago counties.
Stage I vapor recovery is a control strategy that captures gasoline vapors that are released when gasoline is delivered to a storage tank. The vapors are returned to the tank truck as the storage tank is being filled with fuel, rather than released to the ambient air.
Stage II requirements
Stage II vapor recovery systems were required in Kenosha, Kewaunee, Manitowoc, Milwaukee, Ozaukee, Racine, Sheboygan, Washington and Waukesha counties. However, facilities in these counties can now voluntarily remove or decommission their Stage II systems.
Stage II vapor recovery captures gasoline vapors when a vehicle is being fueled at the pump. The vapors are returned through the pump hose to the petroleum storage tank instead of being released into the air. However, newer vehicles are equipped with their own vapor recovery systems, called onboard refueling vapor recovery or ORVR. In 2012, U.S. EPA determined that the use of ORVR is widespread, and that continued use of Stage II systems is redundant. For this reason, Stage II systems are no longer required.
For more information about changes to Stage II vapor recovery requirements in Wisconsin, refer to the following factsheets:
- Stage II Vapor Recovery Rule Changes for Gasoline Dispensing Facilities (AM-492)
- Stage II Decommissioning: Questions and Answers
For more informationa about regulations affecting gasoline dispensing facilities, visit DNR's Small Business Environmental Assistance Program (SBEAP) air regulations. Refer to the gasoline dispensing section (under the Industry Specific tab). The SBEAP compliance calendar for gasoline dispensing facilities contains factsheets summarizing vapor recovery requirements and other relevant regulations.
Related Wisconsin rules
- Chapter NR 420, Wis. Adm. Code - Control of Organic Compound Emissions From Petroleum and Gasoline Sources
- Chapter ATCP 93, Wis. Adm. Code - Regulations for Flammable, Combustible and Hazardous Liquids (administered by the Wisconsin Department of Agriculture, Trade & Consumer Protection Bureau of Weights & Measures)
- Wisconsin HAPs Rule Requirements for Gasoline Dispensing Facilities (AM-524)
- Section NR 445.16, Wis. Adm. Code - Requirement to notify DNR about hazardous substance air spills
- U.S. EPA - Ozone: Stage Two Vapor Recovery Rule and Guidance
- California Air Resources Board Vapor Recovery Program
- Illinois EPA Vapor Recovery Program
- Contact information
- Peter McMullen
DNR Southeast Region
Several voluntary programs are in place to reduce emissions from cars, trucks and other motor vehicles.
Wisconsin Clean Diesel Grant Program
The DNR has established the Wisconsin Clean Diesel Grant Program to help reduce diesel emissions from both public and private vehicle fleets across the state.
Midwest Clean Diesel Initiative (MCDI)
This initiative is a public-private partnership to voluntarily reduce diesel emissions prior to, or in addition to mandatory deadlines. The goal of MCDI is to impact 1 million diesel engines by 2010, through operational changes, technological improvements and use of cleaner fuels.
Wisconsin Clean Diesel Coalition (WCDC)
This is a voluntary coalition of public and private diesel stakeholders in Wisconsin that focuses on educational outreach and development of funding mechanisms to accelerate emission reductions from diesel fleets and support the goals of the MCDI.
Congestion Mitigation and Air Quality (CMAQ)
CMAQ is a federal funded program for transportation projects that improve air quality in counties that are either air quality non-attainment or maintenance areas for federal air standards. The program seeks projects that improve air quality including enhancing public transit and other alternative transportation, technologies that improve traffic flow and vehicle emissions.
In addition, individual actions can help improve air quality. Actions taken by individuals may seem small, but when taken in totality, they add up to cleaner air. Taking mass transit or carpooling, even if it is just once or twice a week, can reduce traffic congestion, pollution, and save money! It costs roughly between 44 cents and 62 cents per mile (depending on car size and type) to own and operate a vehicle. Biking and walking instead of driving is a zero emission way to travel that can help you and the air stay healthy.
- Eco-driving is a fun, easy and inexpensive way to reduce mobile emissions, and anyone can do it! Through eco-driving drivers of any vehicle learn how to use their vehicles efficiently and safely to reduce vehicle emissions and be a safe driver. Log on to Extraordinary Road Trip (XRT) to learn more!
- Fleets in Southeast region have succeeded in saving fuel and reducing emissions while eco-driving through a federal grant. Two fleets trained staff how to eco-drive and saw results immediately! Email DNR Air Education for the curriculum and teach your drivers how to eco-drive.
- Wisconsin Partners for Clean Air
Other regulatory requirements
Federal Motor Vehicle Emission Control Program (FMVECP)
In general, the FMVECP refers to EPA's efforts to set motor vehicle emission standards for newly manufactured cars, trucks, buses and motor cycles. Emission standards are set for engine exhaust and to limit emissions from the fuel management system on the vehicle.
Wisconsin Department of Transportation's Inspection and Maintenance
The purpose of motor vehicle inspection and maintenance is to insure that existing vehicles are maintained and emissions are minimized as the vehicle ages. There are 7 counties in Wisconsin that are required to have motor vehicle inspection and maintenance programs; Kenosha, Milwaukee, Ozaukee, Racine, Sheboygan, Washington and Waukesha counties.
Off-Road Vehicles and Equipment
As with highway vehicles, the EPA sets emissions standards for exhaust and fuel management systems on off-road vehicles and equipment. In general, the emission standards have lagged behind the level control for highway vehicles simply due to the large range of engines and engine applications for off-road equipment.
Reformulated gasoline (RFG) is required by the Federal Clean Air Act in certain areas, including a six-county area in Southeastern Wisconsin. The fuel is especially formulated to reduce volatile organic compound emissions (VOC), emissions of nitrogen oxide compounds (NOx) and certain toxic compounds such as benzene.
Under the Energy Policy Act of 2005, EPA is responsible for promulgating regulations to ensure that gasoline sold in the United States contains a minimum volume of renewable fuel. The Renewable Fuel Standard program will increase the volume of renewable fuel required to be blended into gasoline to 7.5 billion gallons by 2012.
Conformity is a Clean Air Act requirement that serves as a bridge to connect air quality and transportation planning activities and is jointly administrated by the U.S. EPA and U.S. Department of Transportation. The conformity process ensures that federal funding and approval are given to highway and transit projects that are consistent or 'conform' to air quality goals established by a state air quality implementation plan (SIP). Conformity means that transportation activities will not cause new air quality violations, worsen existing violations, or delay timely attainment of the national ambient air quality standards.