See Also
Air
Quality Index
Learn
how air quality is measured and reported.
Air
Pollution Emergencies
What
procedures do we follow?
Contact DEQ
Regional
Office
Air Quality Managers
State
Office
Air Quality Division
Chris
Ramsdell
(208)
373-0237
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Air Monitoring Overview:
How DEQ Assesses Air Quality
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| Throughout
Idaho, DEQ routinely assesses outdoor (ambient) air quality to satisfy
federal regulatory requirements and scientifically determine the
quality of Idaho's airsheds. DEQ's air quality monitoring program
encompasses operation of a monitoring network, laboratory analysis
of air samples, and quality assurance activities to ensure data
integrity. The program collects real-time measurements of ambient
levels of air contaminants at more than 20 sites throughout the
state. Integrated sampling methods are used at another 10 sites.
Data
are used to:
- define the nature and severity of pollution
in Idaho,
- determine which areas of Idaho are meeting the
air quality standards,
- identify pollution trends in the state,
- support smoke dispersion forecasts for agricultural
burning and prescribed fire programs, and
- reconcile air quality models and emission inventories.
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| Criteria Pollutants |
| DEQ's
monitoring network measures the levels of five of the six ambient
air criteria pollutants identified by the federal Clean Air Act.
The criteria pollutants are:
(PM10
= particulate matter less than or equal to 10 microns in diameter;
PM2.5 = particulate matter less than or
equal to 2.5 microns in diameter)
- Carbon monoxide
- Nitrogen dioxide
- Sulfur dioxide
- Ozone
- Lead (Airborne lead is no longer considered
a major health threat in most of the U.S. With the phase-out of
leaded gasoline and closure of the Bunker Hill Mine, DEQ no longer
monitors airborne lead levels.)
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| Quality Assurance |
To
assure that ambient and metorological data collected by Idaho's
air monitoring network meet or exceed required standards, DEQ developed
the Idaho Quality Assurance Manual, Ambient Methods, in 1987. The
manual prescribes detailed operational procedures for sampling,
analyzing, and reporting air pollution and meteorological conditions.
The manual is reviewed annually and revised as needed, subject to
approval by the U.S. Environmental Protection Agency (EPA). The
Idaho Quality Assurance Project Plan, developed in 2002 and finalized
in June 2003, is the latest revision to this base document. |
| Idaho
Quality Assurance Project Plan
(DEQ Publication, June 2003; Latest Revision,
December 2005: pdf 5.7 mb, 494 pages) |
| The document
also has been divided into four sections for easier downloading: |
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| National Ambient Air Quality
Standards |
| To
provide a
quantifiable means to measure air quality, EPA's Office
of Air Planning and Standards, has established standards for six
"criteria
pollutants." For each criteria pollutant, the standard includes
a maximum concentration above which adverse effects on human health
may occur. These threshold concentrations are called National
Ambient Air Quality Standards (NAAQS).
There
are two types of standards: primary and secondary. Primary standards
set limits to protect public health, including the health of "sensitive"
populations, such as asthmatics, children, and the elderly. Secondary
standards set limits to protect public welfare, including protection
against decreased visibility, damage to animals, vegetation, and
buildings. Idaho has adopted the federal air quality standards in
the Rules
for the Control of Air Pollution in Idaho (IDAPA 58.01.01.575-587).
The following
table shows the primary and secondary standards of the six criteria
pollutants for which standards have been developed:
Pollutant
|
Primary Stds. |
Averaging
Times |
Secondary
Stds. |
Carbon Monoxide |
9 ppm
(10 mg/m3) |
8-hour (1) |
None |
35 ppm
(40 mg/m3) |
1-hour (1) |
None |
Lead |
1.5 µg/m3 |
Quarterly Average |
Same as Primary |
Nitrogen Dioxide |
0.053 ppm
(100 µg/m3) |
Annual (Arithmetic Mean) |
Same as Primary |
Particulate Matter
(PM10) |
Revoked (2) |
Annual (2) (Arith. Mean) |
|
150 µg/m3 |
24-hour (3) |
|
Particulate Matter
(PM2.5) |
15.0 µg/m3 |
Annual (4) (Arith. Mean) |
Same as Primary |
35 µg/m3 |
24-hour (5) |
|
Ozone |
0.075 ppm |
8-hour (6) |
Same as Primary |
0.12 ppm |
1-hour (7)
(Applies only in limited areas) |
Same as Primary |
Sulfur Oxides |
0.03 ppm |
Annual (Arith. Mean) |
------- |
0.14 ppm |
24-hour(1) |
------- |
------- |
3-hour(1) |
0.5 ppm
(1300 µg/m3) |
|
(1) Not to be exceeded more than once per year.
(2) Due to a lack of evidence linking health problems to long-term exposure to coarse particle pollution, the agency revoked the annual PM10 standard in 2006 (effective December 17, 2006).
(3) Not to be exceeded more than once per year on average over 3 years.
(4) To attain this standard, the 3-year average of the weighted annual mean PM2.5 concentrations from single or multiple community-oriented monitors must not exceed 15.0 µg/m3.
(5) To attain this standard, the 3-year average of the 98th percentile of 24-hour concentrations at each population-oriented monitor within an area must not exceed 35 µg/m3 (effective December 17, 2006).
(6) To attain this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone concentrations measured at each monitor within an area over each year must not exceed 0.075 ppm.
(7) (a) The standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.12 ppm is < 1, as determined by appendix H.
(b) As of June 15, 2005 EPA revoked the 1-hour ozone standard in all areas except the fourteen 8-hour ozone nonattainment Early Action Compact (EAC) Areas. |
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| Attainment vs. Nonattainment |
Based
upon levels of air pollutants, geographic areas are classified by
EPA as attainment or nonattainment areas. A geographic area that
meets or has pollutant levels below the NAAQS is called an attainment
area. An area with persistent air quality problems
is designated a nonattainment area.
This means that the area has violated federal health-based standards
for outdoor air pollution. Each nonattainment area is declared for
a specific pollutant. Nonattainment areas for different pollutants
may overlap each other or share common boundaries.
States
strive to achieve attainment with state and federal air quality
standards for a number of reasons. First and foremost, remaining
in compliance helps protect public health, a key element of Idaho
DEQ's mission. In addition, compliance contributes to economic growth.
Nonattainment status can potentially limit production capabilities
of existing industries and preclude siting of new industries that
provide job opportunities. Attainment of air quality standards also
helps avoid a potential loss of federal highway funding that can
result from nonattainment status. Lastly, it is costly and time-consuming
to develop and implement plans to reattain attainment status.
In addition to areas classified as attainment and nonattainment, some areas are described as "maintenance areas." Maintenance areas are those geographic areas that were classified as nonattainment, but are now consistently meeting the NAAQS. Maintenance areas have been re-designated by the EPA from "nonattainment" to "attainment with a maintenance plan"; commonly called "maintenance areas." These areas have demonstrated through monitoring and modeling they have sufficient controls in place to meet and main the NAAQS. They also have contingency measures in place that would be implemented should the areas start showing exceedances. more.
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| Nonattainment and Maintenance Areas in Idaho |
| At
present, the following four geographical areas in Idaho are classified
as nonattainment or maintenance areas:
>
View map showing Idaho's nonattainment
areas (pdf 726 kb, 1 page).
Area |
Description |
Pollutant |
Background |
| Sandpoint |
Located in Bonner County, the area rests on
the northwest corner of Lake Pend Orielle within the Panhandle
National Forest. |
PM10 |
The topography influences much of the PM buildup
in the area. In 1997, the area was designated moderate PM10
nonattainment, and an emissions inventory identified the primary
PM10 source as residential wood burning.
Fugitive road dust and some industrial sources are also considered
significant contributors. |
| Pinehurst |
Located in Shoshone County and rests in the
Silver Valley surrounded by the Coeur d'Alene and St.
Joe National Forests. |
PM10 |
The area's topography is a significant
factor in the buildup of pollutants that result in poor air
quality. The emission inventory identified residential wood
burning as the primary PM10 source and
fugitive road dust as a secondary source. |
Portneuf Valley
(Maintenance Area) |
96.6 square miles of Pocatello, Chubbuck,
and surrounding areas |
PM10 |
The Portneuf Valley is a Maintenance Area for PM10. Formerly the Power/Bannock County PM10
area; split into Portneuf Valley and federal Fort Hall PM10
areas. Includes federal land managed by the Bureau of Land Management
and the Caribou National Forest, as well as privately owned
land in the cities of Pocatello and Chubbuck. Link to maintenance plan. |
Northern Ada County
(Maintenance Area) |
Southwestern Idaho |
Carbon Monoxide
(CO)
and
PM10
|
At present, Northern Ada County is a Limited
Maintenance Area for CO. Northern Ada County is Idaho's only designated
CO Maintenance Area. Mobile and area source emissions are the
two major sources of CO. Link to CO maintentance plan.
Northern Ada County is also a Maintenance Area for PM10. The main sources of PM10 are fugitive road dust and agriculture. Link to PM10 maintenance plan.
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Redesignating
Nonattainment Areas |
| Several
nonattainment areas in Idaho now appear to be meeting NAAQS. This
apparent compliance with the federal standards does not automatically
bring an area's nonattainment status to an end, however. The Clean
Air Act requires states to follow an extensive process to prove
that the nonattainment designation should be removed.
DEQ and
local governments are working to gain redesignation in all areas
that are meeting outdoor air quality standards. Redesignation is
a complicated and lengthy process that can take up to two years
for each area. To attain reclassification, the nonattainment area
must meet national ambient air quality health standards as follows:
- Coarse particulate
matter (PM10) and ground-level ozone:
No more than an average of one violation of the standard per year
for three consecutive years.
- Carbon Monoxide:
No more than one violation of the standard each year for two consecutive
years (averaging prohibited; cannot have two violations one year
and none the next).
Data must
be acquired through actual monitoring with equipment located in
places likely to have the highest concentrations of the pollutant.
A computer modeling analysis also must be completed to show that
monitoring occurred in high concentration areas and to support the
case that the standard has been met. Following are the steps that
must be followed:
Develop
a Nonattainment Area Plan
DEQ must
complete and obtain EPA approval of a State Implementation Plan
(SIP) for bringing each area into attainment. The federal planning
process must be completed before completing other redesignation
requirements.
Demonstrate
Proof of Real Pollution Reductions
DEQ must
prove to EPA that the air quality improvements are permanent and
enforceable. Improvements cannot be attributed to unusually favorable
weather conditions or factors such as economic downturns that resulted
in less traffic and industrial activity.
Develop
a Maintenance Plan
DEQ must
develop and obtain EPA approval of a maintenance plan designed to
keep the area's air healthful. This plan must outline the pollution
prevention steps that the state will implement to maintain air quality
standards for 10 years after redesignation is attained. Circumstances
will dictate whether fewer, the same, or additional pollution prevention
strategies will be required. The plan also must describe measures
that will be taken to correct violations if they occur. DEQ may
submit the maintenance plan at the same time it applies for redesignation.
Other
Requirements
| • |
Inventory:
DEQ
must prepare an inventory showing all sources of air pollution
and how much they generate. Sources are things such as vehicles,
wood stoves, and commercial or industrial facilities that
generate air pollution. DEQ must identify the maximum amount
of emissions that can be allowed without violating air quality
standards. |
| • |
Maintenance
demonstration: Using
a computer model, DEQ must demonstrate to EPA's satisfaction
that the maintenance plan will keep air quality within the
federal standards for 10 years, even if the number of pollution
sources increases (for example, increased traffic or more
industrial areas in the area). |
| • |
Monitoring:
DEQ
must submit a monitoring plan that will show whether the federal
standards are being maintained. The plan must allow for special
studies in case traffic patterns or other pollution producing
patterns change. These studies could lead to new permanent
monitoring sites if high pollution persists. |
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| For More Information |
Nonattainment: When Good Air Goes Bad
(DEQ Brochure, May 2008: pdf 279 kb, 2 pages) |
Health
and Air Pollution
DEQ's Web page on the health impacts of exposure to various pollutants.
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| EPA's
Air Quality Index Web Site |
| EPA's
AIRNow Publications |
| A
Guide to Air Quality and Your Health (EPA
Publication) |
Air
Quality Monitoring Locations Map
An interactive, map-based source of information on where DEQ monitors
air quality throughout Idaho. Allows download of real-time air quality
data in each location. (Requires Internet Explorer
5.5 or higher with a screen resolution of 1024 by 768.) |
› Link to 2006 Monitoring Site Quick-look Map
(DEQ Publication, August 2006: pdf 713 kb, 1 page) |
Air
Quality Monitoring Reports
Overviews of Idaho's air monitoring network and levels
of air pollutants monitored in the state. |
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