Guide for  Nitrogen  Dioxide
  Air Quality Index
  Good
  (0-50)
  Moderate
  (51-100)
Protect Your Health Near Roadways
No health impac
ected when air quality is in this range.
-ange.
Individuals who are unusually sensitive to NO2 should consider
limiting prolonged outdoor exertion.

  Unhealthy for Sensitive Groups
  (101-150)
  Unhealthy
  (151-200)
The following groups should limit prolonged outdoor exertion:
  • People with lung disease, such as asthma
  • Children and older adults
The following groups should avoid prolonged outdoor exertion:
  • People with lung disease, such as asthma
  • Children and older adults
Everyone else should limit prolonged outdoor exertion.
  Very Unhealthy
  (201-300)
The following groups should avoid all outdoor exertion:
  • People with lung disease, such as asthma
  • Children and older adults
Everyone else should limit outdoor exertion.
What You Should Know About Nitrogen Dioxide and Your Health

 •  Nitrogen dioxide comes from vehicle, power plant, and industrial emissions and off-road sources such
    as construction, lawn and gardening equipment.
 •  People who live or work near busy roadways can experience high exposures.
 •  Find out more about air quality through TV, radio, newspapers, AIRNow (www.airnow.gov) and
    EnviroFlash (www.enviroflash.info), so you can take steps to protect your health.

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Revisions to the National Ambient Air
Quality Standards for Nitrogen Dioxide

On January 22,2010, EPA strengthened the health-
based National Ambient Air Quality Standard
(NAAQS) for nitrogen dioxide (NC>2). EPA set a
new I -hour NO2 standard at the level of 100 parts
per billion (ppb). EPA also retained the current annual
average NO2 standard of 53 ppb.

The new  I -hour standard will protect public health
by limiting people's exposures to short-term peak
concentrations of NO2 - which primarily occur near
major roads. Community-wide NC>2 concentrations
will be limited  to levels below those that have been
linked to  respiratory-related emergency room visits
and hospital admissions.

Additionally, EPA established  new ambient air
monitoring and reporting requirements for NC>2.
In urban areas, monitors are  required  near major
roads and in other locations  where maximum
concentrations are expected. EPA has placed a
number of monitors in locations to help protect
communities that are susceptible and vulnerable to
NC>2-related health  effects.
                                      of adverse effects on the respiratory system. NOx
                                      reacts with ammonia, moisture, and other compounds
                                      to form small particles. These small particles can
                                      penetrate deeply into sensitive parts of the lungs.
                                      How does nitrogen dioxide affect health?

                                      Scientific evidence links short-term NC>2 exposures,
                                      ranging from 30 minutes to 24 hours, with adverse
                                      respiratory effects including airway inflammation in
                                      healthy people and increased respiratory symptoms in
                                      people with asthma.

                                      Studies also show a connection between short-term
                                      exposure and increased emergency room visits and
                                      hospital  admissions for respiratory illnesses.
                                      Who is sensitive to nitrogen dioxide?

                                      Individuals who spend time on or near major roads
                                      can experience NC>2 exposures considerably higher
                                      than occur away from roads.  These exposures are of
                                      particular concern for sensitive groups, such as people
                                      with lung disease including asthma.
What is nitrogen dioxide and where does it
come from?

EPA's NAAQS for NC>2 is designed to protect against
exposure to the entire group of nitrogen oxides
(NOx).  NO2 is the component of greatest concern
and is used as the indicator for the larger group of
NOx. The sum of nitric oxide (NO)  and NO2 is
commonly called NOx. Other nitrogen oxides include
nitrous acid and nitric acid. NOx reacts with volatile
organic compounds to form ozone.

NO2 forms from the emissions of vehicles, power
plants, industrial sources, and off-road equipment,
such as construction vehicles and lawn and garden
equipment. In addition to contributing to ground-
level ozone formation, NO2 is linked with a number
                                      Does my community have unhealthy NO2 levels?

                                      Unlike ozone and particle pollution, which can be
                                      of concern over large regions, NO2 levels are
                                      appreciably higher in close proximity to pollution
                                      sources (e.g., vehicles on major freeways, factories).
                                      Health  effects associated with NO2 are much less
                                      likely farther away from these pollution sources.

                                      NO2 in heavy traffic or on freeways can be two times
                                      as high  as levels measured in residential areas or on
                                      lesser traveled roads. Monitoring studies have shown
                                      that within approximately 50 meters of heavy traffic/
                                      freeways, NC>2 concentrations may be 30 to 100
                                      percent higher.
  What You Can Do To Reduce NO2 Emissions
  •   Carpool or use public transportation.
  •   When air quality is healthy, bike or walk instead of driving.
  •   Combine errands to reduce vehicle trips.
  •   Limit engine idling.
  •   When refueling avoid spilling fuel. Tighten gas cap securely.
  •   Keep your car, boat, and other engines tuned up.
  •   Inflate car tires to the recommended pressure.
  •   Conserve energy at home and at work
                                                          Office of Air and Radiation (6301 A)
                                                          EPA Document # EPA-456/F-10-002
                                                                         www.airnow.gov
                                                                           October 2010
  oEPA
United States
Environmental Protection
Agency	

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