Background
Nitrogen dioxide (NO2) is one of a group of highly reactive gases known as "oxides of nitrogen," or "nitrogen oxides (NOx)." NO2 forms quickly from emissions from cars, trucks and buses, power plants, and off-road equipment. In addition to contributing to the formation of ground-level ozone, and fine particle pollution, NO2 is associated with a number of adverse effects on the human respiratory system.
Health studies have linked short-term NO2 exposures, (30 minutes to 24 hours) with adverse respiratory effects including airway inflammation in healthy people and increased asthma symptoms, respiratory symptoms and illnesses. Also, studies show a connection between breathing elevated short-term NO2 concentrations, and increased visits to emergency rooms and hospital admissions for respiratory issues, especially asthma. NO2 reacts to form fine particles which can cause or worsen respiratory diseases, such as emphysema and bronchitis and aggravate heart disease leading to increased hospital admissions and premature death.
Individuals who spend time on or near major roadways can also experience short-term NO2 exposures considerably higher than currently measured. NO2 exposure concentrations near roadways are of particular concern for susceptible individuals, including people with asthma, children, and the elderly.
| Agency | Action | Status and documents |
|---|---|---|
US EPA |
NAAQS | |
| NO2 Designation | Letter to CA Governor on NO2 Designation (PDF) 06-29-11 | |
CARB |
Designations Letter & Technical Support Document |
Submittal Letter (PDF) 01-24-11 |
SIP Revision |
Proposed NO2 Infrastructure SIP (PDF) 10-15-12 | |
District Board |
Pending |
Pending |
District (staff) |
Letter |
Boundary Recommendations Letter (PDF) 01-11-11 |