Highest 1-Hour Concentration of NO2
This threshold indicator has been retired and is no longer reported.
Highest 1-Hour Concentration of NO2 is include in the Threshold Dashboard. Threshold Indicators are evaluated against Threshold Standards every 4 years. Thresholds are environmental goals and standards for the Lake Tahoe Basin that indirectly define the capacity of the Region to accommodate additional land development.
Status
NOx concentrations as measured at the newly established TRPA Stateline monitoring location. While no official TRPA standards exist for NOx concentrations, this data is used to evaluate NOx concentrations against CA and Federal standards. Source: TRPA
Desert Research Institute
Evaluation Map
TRPA Stateline NOx monitoring location.
2015 Evaluation
- Status
- At or Somewhat Better Than Target
- Trend
- Moderate Improvement
- Confidence
- High
Applicable Standard
California: highest one-hour, not to exceed 0.18 ppm; Nevada/Federal: highest one-hour NO2 concentration not to exceed 0.10 ppm.
Key Points
No Key Points
About the Threshold
- This indicator estimates daily emissions of nitrogen oxides (NOx) based on the California Air Resources Board (CARB) emission inventory for the California portion of the Lake Tahoe Region and the recently installed monitoring at the TRPA offices in Stateline, Nevada. Nitrogen dioxide (NO2) is one of a group of highly reactive gasses known as “nitrogen oxides.” Other nitrogen oxides include nitrous acid and nitric acid. While federal standards cover the entire group of NOx. NO2 is the component of greatest interest and the indicator for the larger group of NOx. In addition to contributing to the formation of ground-level ozone and fine particle pollution, NO2 is linked with regional haze, global warming, water quality degradation, and a number of adverse effects on the respiratory system (EPA 2011c). Current scientific evidence links short-term NO2 exposure 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 (EPA 2011b).
- Ozone is considered a secondary pollutant, created by photochemical reactions between hydrocarbons (HC) and oxides of nitrogen (NOx) in sunlight. The sources of HC and NOx include mobile sources (cars, trucks, boats, aircraft, off-road vehicles, etc.), biomass burning (wood stoves, wildfires, prescribed burning), and consumer products such as solvents. Ozone is transported from populated areas around the Lake Tahoe Region into the basin, and the ambient concentration of O3 is highly dependent on meteorological conditions such as sunlight, temperature, wind speed and mixing conditions.
Delivering and Measuring Success
Rationale Details
- Considerably better than target.
Concentrations (NOx ppb): Annual Average Concentration: 2014 data from the TRPA Stateline site shows an annual average concentration of 4.1 ppb, 14 percent of the strictest California standard of 30 ppb. Highest 1-hour Concentrations: 2014 data from the TRPA Stateline site shows an annual high 1-hour concentration of 27.9 ppb, 15.5 percent of the strictest California standard of 180 ppb. Both of these are “considerably better than target.” - Moderate improvement. The long-term trend line for average tons per day of NOx emissions shows an annual decrease of 1.5 percent. Therefore, a trend of moderate improvement was determined. Additionally, a very strong decreasing trend is evident from 1990 onward with consistent reductions in NOX levels.
Confidence Details
- High. Data is collected following well-established protocols for air quality monitoring, therefore confidence in the status is high.
- Moderate. The overall improving trend in emissions reported by CARB is moderate (R² = 0.5538, P = 0.014). Trend from the Stateline site is not applicable because only two years of data exists.
- Moderate. Overall confidence takes the lower of the two confidence determinations.
Additional Figures and Resources
No photos available.
No documents available.