Ambient Air
The outside air all around us.

Air Monitoring Comparison Values
AMCV’s are chemical specific air concentrations set to protect human health and welfare. Exposure to an air concentration at or below the AMCV is not likely to cause adverse health effects. AMCV’s are a collective term that refers to all values used by TCEQ to review ambient air monitoring data.

Benzene
Benzene is an organic chemical compound, a natural constituent of crude oil and a constituent in gasoline. Benzene is classified as a human carcinogen. Long-term exposure to excessive levels of benzene in the air may cause leukemia.

Butadiene
This industrial chemical is used in the production of synthetic rubber. Typically, butadiene refers to 1,3-butadiene, which is listed as a known carcinogen by the EPA.

Design Value for the 8-Hour Ozone Standard
This refers to a value calculated according to a formula from EPA, and is based on three-year averages of the fourth-highest value at each monitor.

Ozone
Ground-level ozone is an air pollutant that can harm lung function and irritate the respiratory system. It is formed by the reaction of sunlight on air containing hydrocarbons and nitrogen oxides.

ppm
Stands for parts per million. One ppm has the time equivalent of 32 seconds in a year.

ppb
Stands for parts per billion. One ppb has the time equivalent of 3 seconds in 100 years.

TCEQ
Texas Commission on Environmental Quality, the government agency that regulates environmental matters in Texas.

Volatile Organic Compounds
VOCs are emitted as gases to the air. They include a variety of chemicals, some of which may have short- and long-term adverse health effects