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Skip Navigation LinksDNREC : Division of Air Quality : Air Toxics Assessment Study

 Delaware Air Toxic Assessment Study (DATAS)



What are air toxics?
Toxic air pollutants, also referred to as air toxics or hazardous air pollutants (HAPs), are chemicals that, at sufficient concentrations and exposures, are known or suspected to cause cancer. HAPs can also cause other serious health effects or cause adverse environmental effects.

Air toxic pollutants of greatest concern are those that are released to the air in amounts large enough to create a risk to human health and in which many people may be exposed.

Air toxic pollutants may exist as particles or gases. Air toxics that exist as particles can include heavy metals, such as cadmium, mercury, chromium, and lead compounds, as well as organic compounds, such as polycyclic aromatic hydrocarbons (PAHs), which are emitted during the combustion of fossil fuels and wastes. Gaseous air toxic pollutants include benzene, toluene, and xylenes, found in gasoline; perchloroethylene, used in dry cleaning; and methylchloride used as a solvent by various industries.

What are the sources of air toxics?
Air toxics can be produced from both stationary sources, either point or area sources, and mobile sources. Point sources include facilities that report emissions, including power plants, manufacturers, refineries, large office buildings, landfills, hospitals, incinerators, and government facilities. Smaller stationary sources or area sources include dry cleaners, printers, and automobile paint shops.  Mobile sources include both on- and off-road motor vehicles, as well as boats and aircraft. Some air toxics are released from natural sources, including volcanoes, radon gas, and emissions from forests. Although natural sources of air toxics exist, most toxics originate from man-made sources.

DATAS determined that 68 percent of the mass of emissions come from mobile sources, 23 percent come from area sources, while 9 percent are contributed by point sources.

What is the NATA study, and how does it relate to DATAS?
The United States Environmental Protection Agency (EPA) brought attention to air toxics through a nationwide study known as the National Air Toxics Assessment (NATA). NATA is a comprehensive nationwide air quality study which was released by EPA in 2000 using 1996 air toxics data. The study has been updated with air toxics data from 1999, which will be released to states in 2005. 

NATA identified certain air toxics that pose the greatest risk on a national or regional level. However, in many cases, EPA was unable to develop local estimates of air toxics emissions and relied on national default values to generate much of the emissions data that went into the NATA analysis. DNREC-AQM designed DATAS to quantify risk from air toxics at the local level with Delaware-specific monitoring and emissions inventory.

What does DATAS include?
DATAS is the Delaware Air Toxics Assessment Study project, initiated by the Air Quality Management Section of DNREC in early 2002 to gain a better understanding of ambient concentrations of air toxics throughout Delaware. 

The study was initiated as a result of the Governor’s Cancer Task Force which recommended evaluating environmental factors including the risk from air toxics. DNREC has been joined by the Delaware Department of Health and Social Services’ Division of Public Health and the Cancer Consortium in conducting risk assessments for the contaminants of concern and evaluating the results. 

The DATAS project consists of five major components:

  • Monitoring Data - collected at the five locations in 2003
  • Emissions inventories for point and mobile sources (2002 to 2003)
  • Modeling (both local and regional)
  • Risk assessment
  • Outreach/communications

How were the five monitoring sites chosen?
For the air quality monitoring component, the five sites were selected based upon the following criteria:

  • Population within the area surrounding the site.
  • Location of the site relative to industrial facilities.
  • Location of the site relative to major roadways.
  • Ability of existing infrastructure at the site to support additional toxics instrumentation.
  • Incorporation of sites already equipped with air toxics instrumentation.

From where do the pollutants originate that were observed at the monitoring sites?
Sources contributing to the ambient concentrations of air toxics observed at the monitoring sites can include point sources, area sources, and on-road and off-road mobile sources. These sources can be located in Delaware, near the monitors, as well as located upwind of Delaware in another state. Certain pollutants, in part, form in the atmosphere from other pollutants in a process called photochemistry.

The monitors do not readily tell us from where the pollutants originate. In general, the emission inventory matches what the monitors found. As an example, some volatile organic compounds were not observed at the monitors, and sources for these same pollutants were not found in Delaware when the inventory was developed.

The modeling effort of Phase II will account for the transport of emissions from sources inside and outside of Delaware. The modeling results can be analyzed to associate sources contributing to a particular ambient concentration. DNREC will use this information to determine which sources contribute most to the calculated cancer and non-caner risks throughout Delaware.

What is risk assessment?
Risk assessment is the analysis that uses information about toxic substances to estimate a theoretical level of risk for people who might be exposed to these substances. The information comes from scientific studies and environmental data. Risk assessments are conducted for a number of reasons, including:

  • To determine if levels of toxic substances pose an unacceptable risk as defined by regulatory standards and requirements.
  • To establish whether an environmental health risk exists or not.
  • To identify the need for additional data collection.
  • To focus on the dangers of a specific pollutant.
  • To focus on the dangers of a specific site.
  • To help develop contingency plans and other responses to pollutant releases.
  • To help regulatory officials determine strategies that will ensure overall protection of human health and the environment.

What do the risk assessments in DATAS seek to determine?
Risk assessments seek to determine an acceptable (negligible) level for each potentially dangerous contaminant present. For humans, this is a level at which adverse health effects are unlikely and the probability of cancer is very small.

What components were used to determine the risks for cancer and non-adverse health effects?
The components include:

  • Hazard Identification – The determination and sampling of what chemicals may be at the site.
  • Exposure Assessment – Any of the ways for human contact with the contaminant, including who are the likely receptors of the exposure and how often this contact has or will occur.
  • Toxicity Assessment – The levels of the contaminants of concern at the site and what effects they are likely to have on human health
  • Toxicity Assessment – The levels of contaminants of concern at the site and what effects they are likely to have on human health.
  • Risk Management – The options and recommendations regarding what to do about these contaminants ranging from no action to removal to using barriers to prevent exposure.

What does risk assessments measure?

  • For cancer effects, risks are expressed as probabilities of additional cases of cancer above the expected background level.
  • For non-cancer effects, exposure levels are compared to pre-established levels at which negative (adverse) health effects are not expected.
  • The risk assessment provides an estimate of theoretical risk or hazard assuming no changes in exposure take place over the time of the modeling.
  • Risk assessment focuses on current and future exposures. It predicts into the future, rather than being retrospective.

What doesn’t risk assessments measure?

  • Risk assessment does not measure the actual health effects that hazardous substances have on people.
  • Risk assessments do not predict the incidence of disease.
  • Predictions do not absolutely mean that an actual cancer case will exist.
  • People will not necessarily become sick even if they are exposed to compounds at higher dose levels than those estimated by the risk assessment.

How does DATAS relate to the Delaware Cancer Consortium?
The results of the DATAS project are expected to meet the Cancer Consortium’s environmental objectives included in the Governor’s Cancer Task Force Plan to:

Learn more about the possible health risks of ambient exposure to toxins.
Promote the exchange of useful information to Delawareans.
Understand where risks can be avoided.
Provide information from which proactive decisions and good policies can be developed.

In addition, DATAS will be used to (1) establish air quality standards based on risk, (2) establish control strategies for the purpose of meeting the new standards, (3) improve future emission inventory work, and (4) assist state and federal permitting programs in basing decisions on cumulative impacts.

Have similar air toxics studies been conducted in other states?
A few major studies in other states include:

DATAS is more comprehensive than the PATA, WLATS, Houston, and Denver air toxics studies.

How will DATAS be used in the future?
With DATAS, the State of Delaware now has a modeling tool that can be used with future inventories to assess ambient concentrations and risk in the future. The DATAS modeling will enable a better understanding of ambient concentrations of air toxics in communities and their exposure to those air toxics. It will help evaluate related health risks to those communities and initiate an effort to mitigate any adverse impacts.

DATAS will be used to assess air toxics health impacts in communities other than those monitored, defining risk-based air quality standards, and developing control strategies for meeting these standards. Through the DATAS project, DNREC and DPH will continue their collaborative efforts, along with the EPA and Cancer Consortium, to evaluate air toxics and help protect the health and well-being of Delawareans.

How will DNREC, DPH, and the Delaware Cancer Consortium communicate the DATAS results to the general public?
Extensive outreach and education efforts are planned for 2005-2006. Beginning in January 2006, public information forums designed to educate Delawareans residing near a monitoring location will be held. The four forums, a collaborative effort of DNREC, DPH, and the Delaware Cancer Consortium, will include exhibits with materials on all aspects of DATAS. Forum attendees will have the opportunity to meet with representatives from DNREC, DPH, and the Cancer Consortium and ask questions on a one-to-one basis. 

Once Phase II is completed, additional public outreach and education workshops will communicate the results of Phase II and the statewide Risk Management plan.

Community awareness and public involvement are vital to DNREC’s goals of reducing air toxic pollutants and improving the air that we breathe. To this end, DNREC will develop partnerships with organizations and individuals to more effectively communicate programs, improve air quality, and help mitigate any adverse impacts of air toxics.

What programs does DNREC currently have in place to reduce air toxics and improve Delaware’s air quality?
DNREC is working every day to reduce the public health risks for toxic air pollutants. Through former Governor Ruth Ann Minner’s “Livable Delaware” initiative, programs such as the Alternative Commuting Initiative and “Ride Share Delaware” are helping make a difference by encouraging Delawareans to reduce air pollution. In addition, DNREC is promoting air quality planning into the land use approval process to promote “Livable Delaware” growth management goals. 

DNREC is responsible for statewide air quality monitoring and communications, issuing ozone advisories. Through DNREC’s enforcement and permitting programs, air toxic pollutants are regulated. Other programs, the Toxics Release Inventory, the Clean Air Act for Motor Vehicles, and the Enhanced Inspection and Maintenance Program, are in place to reduce air toxic pollutants and improve air quality. 

DNREC has fostered partnerships with stakeholders, government agencies, and industry and community groups, which have led to programs that address Delaware’s air quality. Partners, including the Metropolitan Planning Organizations (MPOs), the Transportation Management Association (TMA), the Delaware Division of Public Health, DelDOT, and Astra Zeneca, have been instrumental in such programs as the Ozone Action Partnership and the Ozone Action Awareness Week. 

A partnership with the Delaware Soybean Board, a farmer-led organization working to promote a more profitable soybean industry, has resulted in the use of a cleaner-burning alternative to diesel fuel, now used at DNREC’s Indian River Marina and by State of Delaware fleets. Thanks to the efforts of partnerships between the Delaware Soybean Board, the Delaware Department of Agriculture, and DNREC, environmentally-friendly fuels including soy biodiesel and ethanol are now available at public fueling locations throughout the state. 

DNREC’s Green Energy Program, Technology Demonstration Program, Research and Development Program, Clean State Program, ENERGY STAR Program, and partnership in the Delaware Bioenergy Consortium – all provide effective ways and incentives to improve air quality through the use of renewable energy technologies, including wind, solar, geothermal, and biomass energy, alternative fuel vehicles, and energy efficiency practices. 

DNREC ombudsmen and educators have developed presentations, materials, and exhibits designed to educate school children and the general public on air quality. They travel to schools and public events and meetings throughout the state educating our citizens on ways they can reduce hazardous air pollutants and improve the air that we breathe. 

For more information contact: 

Jim Snead
(302) 323-4542

Revised: 5/17/16


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