Frequently Asked Questions
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- What are toxic air pollutants?
- Where do toxic air pollutants come from?
- What do we know about air toxics trends in the ambient air?
- What are EPA New England and the states doing about air toxics?
- What future work is EPA planning to assess the health risks posed by air toxics?
- Where can I get information on air toxics monitoring?
- What is EPA doing about air toxics in urban areas?
- What is the Residual Risk Program?
Toxic air pollutants (air toxics) are those pollutants that are known or suspected to cause cancer or other serious health effects, such as reproductive effects or birth defects, or to cause adverse environmental effects. The degree to which a toxic air pollutant affects an individual's health depends on many factors, including the quantity, duration, and frequency of exposures, the toxicity of the chemical, and the individual's personal susceptibility. Under the 1990 Clean Air Act Amendments, EPA is required to address 188 toxic air pollutants.
There are literally thousands of sources of air toxics. We are exposed to some of these pollutants often in the form of gasoline, dry cleaning agents, cleaning solvents, and paint strippers. Large and small manufacturing facilities as well as people's daily automobile driving all contribute to air toxic pollution.
A review of available air toxics monitoring data in New England, however, shows that for most of the pollutants we are seeing a downward trend or levels have remained relatively stable, depending on the compound and location, from 1996 to 2014 in ambient air concentrations at various monitoring locations for 1, 3-butadiene (PDF) (1 pg, 12 K), acetaldehyde (PDF) (1 pg, 12 K), acrolein (PDF) (1 pg, 11 K), arsenic (PDF) (1 pg, 9 K), benzene (PDF) (1 pg, 13 K), carbon tetrachloride (PDF) (1 pg, 13 K), chromium (PDF) (1 pg, 8 K), formaldehyde (PDF) (1 pg, 12 K), benzo(a)pyrene (PDF) (1 pg, 9 K) and naphthalene (PDF) (1 pg, 10 K). EPA reviewed the available monitoring data from the Air Quality System (AQS) data base for the following compounds: 1, 3-butadiene, carbon tetrachloride, chromium VI, benzene, acetaldehyde, acrolein, naphthalene, benzo(a)pyrene, formaldehyde and arsenic. To determine if there were sufficient data to show a trend for these compounds, the following criteria were used: five years or more of data, sampling was performed either on a one-in-three day, a one-in-six day, or a one-in-twelve day frequency, data capture of 75% or greater for the year, each data point needed to represent a 24-hour average concentration, and all reported values in AQS were used to calculate the annual mean (this includes zero's/non-detects and values below the minimal detection limit).
Although much has been done to reduce air toxics pollution, more needs
to be done to solve the air toxics pollution problem. Under the 1990
Amendments, Congress instructed EPA to set air toxic standards (called
MACT standards) which reflect demonstrated technology for specific industrial
source categories. As a result of this approach, EPA has succeeded in
issuing over 90 standards covering numerous industrial categories, such
as pulp and paper mills, chemical plants and wood furniture manufacturers,
as well as some categories for smaller sources like drycleaners. EPA
estimates that these standards, once fully implemented, will result in
reductions of approximately 1.5 million tons of air toxics nationwide.
For more information on specific MACT standards »
In New England, EPA New England staff provide technical assistance to the regulated community to ensure compliance with the air toxics regulations. EPA regulatory personnel also conduct inspections at facilities to ensure compliance. EPA New England provides communities and the various industry sectors in New England with information on how to comply with environmental requirements and how to prevent pollution by minimizing waste. In addition, the states also assist in implementation of the federal and state air toxics regulations in New England.
In addition to developing industry specific MACT regulations, EPA is working to reduce air toxic emissions from accidental releases, including leaks and spills. For example, EPA has established regulations under the Clean Air Act requiring certain facilities to implement risk management programs that will help prevent accidental releases of air toxic chemicals.
EPA is also working to reduce toxic emissions from mobile sources, such as cars and trucks. For example, EPA and state governments have reduced emissions of benzene, toluene, and other air toxics pollutants from mobile sources by requiring the use of reformulated gasoline and placing limits on tailpipe emissions.
To see a discussion of EPA New England's review of 2011 National Scale Air Toxics Assessment (NATA) including a comprehensive discussion of efforts in New England to address air toxics go to New England Results of the 2011 National Air Toxics Assessment.
A critical piece of EPA's action plan to reduce risks posed by air toxics is to develop a better understanding of those risks. EPA has set a national goal to reduce air toxics emissions by 75% from 1993 levels and to reduce significantly the risk of cancer and other serious adverse health effects caused by air toxics. EPA set this goal to meet requirements of the Government Performance and Results Act (GPRA), which requires the Agency to report on the status of its progress in implementing programs. To develop the most effective strategies to meet this goal (and to assess progress in meeting the goal), the Agency needs solid information on air toxics emissions, the ambient levels of the numerous air toxics, people's exposure to air toxics, and the health risks due to inhalation. In the past, such information, and the tools to gather the information, have been limited.
Consequently, EPA has developed the National Air Toxics Assessments (NATA) initiative to develop a comprehensive understanding of air toxics problems and their potential solutions. NATA includes a number of different assessment activities, including efforts to develop updated emissions inventories, air quality dispersion modeling, exposure modeling and risk assessment, as well as air toxics monitoring. EPA has completed the 2011 National Scale Air Toxics Assessment which evaluates risk based on air quality dispersion modeling and exposure modeling. For more information on the four steps under the National Scale Assessment go to Important Background Information on EPA's 2011 National Scale Assessment link here.
EPA plans to conduct national screening-level assessments every three years, with the next assessments focusing on 2008 data. This effort is a large-scale effort to characterize risks broadly. States, local and Tribal governments are already underway with efforts to collect comprehensive data from sources of air toxics emissions in 2008. These NATA efforts are critical for us to develop strategies to address the current air toxics problems, as well as to help us track the progress we have made to date.
Go to EPA's website on this NATA efforts for more information.
EPA outlined its plan for a national ambient air toxics monitoring network in the Air Toxics Monitoring Concept Paper, issued February 29, 2000 (PDF) (44 pp, 266K). The Concept Paper was later revised and EPA outlined a national program and strategy in the National Monitoring Strategy Air Toxics Monitoring Component (PDF) (77 pp, 331 K). As discussed in the strategy, the national air toxics monitoring program is comprised of four different monitoring efforts: National Air Toxics Trends Stations (NATTS); EPA funded local scale projects to assess conditions at the local level; Existing state and local program monitoring; and Persistent bio-accumulative toxics monitoring. The New England states all collect some ambient monitoring data for various air toxics as a part of these efforts.
On July 19, 1999, EPA released the Integrated Urban Air Toxics Strategy. This strategy presents a broad framework for addressing air toxics in urban areas from stationary sources as well as mobile sources. As a first step, EPA has identified 33 of the 188 toxic air pollutants that present the greatest potential threat to public health in the largest number of urban areas. It also identifies categories of "area" or smaller sources that emit air toxics and could be subject to future emission standards. Through three separate listings (including a list in the Urban Air Toxics Strategy), EPA has identified a total of 70 area source categories to develop regulations for.
Under the Clean Air Act, EPA is required to develop and implement a program for assessing risks remaining (i.e., the residual risk) after facilities have implemented maximum achievable control technology (MACT) standards. If necessary, EPA is required to issue regulations to reduce any residual risks in order to protect the public health with an "ample margin of safety". Also, if needed, EPA is required to prevent "adverse environmental effects", taking into consideration costs, energy, safety and other relevant factors. If needed, EPA must issue risk-based regulations, within eight (or nine) years after EPA issues an air toxics standard for a given source category.
On March 3, 1999, EPA issued the Residual Risk Report to Congress. The report describes the methodologies and data required for assessing if any residual risk remains from air toxics emissions from source categories for which MACT standards have been issued. This report also presents the general framework EPA will use in conducting the risk assessments.
A number of MACT source categories are currently being evaluated under the residual risk program.