Air Pollution from Nitrogen Dioxide
- What is nitrogen dioxide?
- Latest air quality planning to address the standard for nitrogen dioxide
- Related Web pages and publications
- Get more information on the Texas SIP and contact the TCEQ
What is nitrogen dioxide?
The sum of nitric oxide (NO) and nitrogen dioxide (NO2) is commonly called nitrogen oxides (NOx). Other compounds, including nitrous acid and nitric acid, are part of the NOx family. NO2 is the component of greatest interest and the indicator for the larger group of 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 linked with a number of adverse effects on the respiratory system.
Latest air quality planning that addresses the standard for nitrogen dioxide
Last updated: 3/16/2011
On February 9, 2010, the United States Environmental Protection Agency (EPA) published a final rule in the Federal Register to strengthen the primary National Ambient Air Quality Standard (NAAQS) for nitrogen dioxide, establishing a new one-hour standard at 100 parts per billion (ppb). The new standard focuses on short-term exposures to NO2, which are generally highest on and near major roads. Currently, no area in Texas monitors above the 100 ppb standard. The EPA is retaining the current annual average NO2 standard of 53 ppb. The EPA is changing the monitoring network to capture both peak NO2 concentrations that occur near roadways and community-wide NO2 concentrations. Approximately 126 new NO2 monitoring sites will be placed near major roads in 102 urban areas nationwide. About eight new monitoring sites are anticipated in Texas and will likely include the Dallas-Fort Worth, Houston-Galveston-Brazoria, San Antonio, Austin-Round Rock, El Paso, and McAllen-Edinburg-Mission areas.
On September 16, 2010, a presentation to the public on the NO2 NAAQS was hosted at the TCEQ Austin Headquarters and video teleconferenced to the five areas in which the EPA is requiring near-road monitors. Two informal comments were submitted by Entergy Services and the Eight-Hour Ozone SIP Coalition.
The commissioners approved the 2010 NO2 NAAQS designation recommendation at the November 18, 2010, agenda. The commission recommends an attainment designation for all areas of the state currently monitoring the one-hour NO2 standard in Texas and an unclassifiable/attainment designation for all other areas in Texas. State designation recommendations were signed by the governor and sent to the EPA on January 22, 2011.
In January 2012, the EPA will finalize initial designations for all areas in the United States. New near-road NO2 monitors must begin operating no later than January 1, 2013. In 2016 or 2017, once the expanded network of NO2 monitors is fully deployed and three years of air quality data have been collected, the EPA intends to redesignate areas based on data from the new monitoring network. The 2010 NO2 NAAQS attainment date is January 2021 or 2022, approximately five years after the date of nonattainment designations.
Related Web pages and publications
- EPA General Page on Nitrogen Dioxide
- Primary NAAQS for Nitrogen Dioxide
- Secondary NAAQS for Nitrogen Dioxide
- Complete List of Texas SIP Revisions
