Saturday declared Ozone Action Day

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The Texas Commission on Environmental Quality (TCEQ) has issued an Ozone Action Day for the Austin area for Saturday, June 8, 2019.

Atmospheric conditions are expected to be favorable for producing high levels of ozone air pollution in the Austin area on Saturday.  You can help prevent ozone pollution by sharing a ride, walking or riding a bicycle, taking your lunch to work, avoiding drive-through lanes, conserving energy, and keeping your vehicle properly tuned.

For more information on ozone:

EPA Air Now

Take Care of Texas

Capital Area Council of Governments Air Quality

CLEAN AIR Force of Central Texas

Ozone: The Facts

Sound science and targeted regulations have greatly reduced ozone concentrations in Texas cities and across the nation.

The Texas Commission on Environmental Quality uses scientific research to develop effective strategies to reduce ozone concentrations. Texas has devoted millions of dollars to air quality research during the past decade, including two major field studies—the Texas Air Quality Study 2000, the Texas Air Quality Study II—and numerous smaller scale studies throughout the state.

Ozone-reduction strategies, developed from knowledge gained through research, have decreased ozone statewide—by 29 percent from 2000 to 2014. By comparison, the rest of the nation averaged only a 16 percent decrease over the same period.

The TCEQ’s goal is sensible regulation, based on sound science, that addresses real environmental risks while complying with state and federal statutes.

What is ozone?

Ozone, sometimes referred to as smog, is a gas that is formed in the atmosphere when three atoms of oxygen combine. The chemical structure of ozone is the same wherever it is found; however, there are two categories of ozone.

Stratospheric Ozone is found naturally in the Earth’s upper atmosphere – 6 to 30 miles above the Earth’s surface – where it forms a protective layer that shields us from the sun’s harmful ultraviolet rays.

Ground-Level Ozone is found at ground level (it is also called tropospheric ozone). It is not emitted directly into the air, but created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. Emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOCs. In addition, biogenic sources (living organisms or biological processes) release VOCs that can contribute to ground-level ozone.

What are the health effects of ground-level ozone?

Ground-level ozone is of particular importance because it is a respiratory toxic agent that can cause acute respiratory health effects when people breathe high concentrations of it over several hours. These effects include decreased lung function and pain with deep breaths, and aggravated asthma symptoms.

What conditions lead to elevated ground-level ozone concentrations?

Summer days in Texas can be conducive for ozone formation as high-pressure systems dominate our local weather patterns, giving us clear skies and stagnant winds. Ozone mainly forms in the highest concentrations on warm, sunny days with light wind speeds, which allows more of the pollutant to form and accumulate.

What about indoor air quality?

The United States Environmental Protection Agency (EPA) has identified and characterized significant risks to public health from indoor environmental contaminants that are commonly found in homes, schools, offices, and other buildings where, on average, Texans are spending about 90 percent or more of their time. It is possible for indoor levels of air pollutants to reach up to two to five times higher, and occasionally even 1,000 times higher, than outdoor levels—according to the Texas Department of State Health Services (DSHS).

Common indoor air contaminants include radon, tobacco smoke, cleaning products, chemicals in upholstery foam, mold, combustion by-products, and VOCs. Ozone is not typically an indoor air contaminant. However, ozone generators, which are sometimes used in homes as air purifiers, may cause harmful levels of ozone.

Building systems, such as heating, ventilating, and air conditioning, also have a direct influence on the type and amount of exposure occupants may experience from indoor environmental contaminants.

For more information on indoor air quality visit:


Should I limit exercise and stay indoors when ozone concentrations are elevated?

The World Health Organization ranks physical inactivity as a major risk factor for heart disease, breast cancer, colon cancer, and diabetes. The Centers for Disease Control and Prevention found that 27.2 percent of adults and 16.6 percent of youth in Texas were inactive in 2014. For children, the risks of obesity are well-documented.

Many people engage in physical exercise to prevent disease and obesity. Individuals must consider those benefits when making choices about whether to follow the EPA’s recommendation to limit exercise outdoors and stay indoors when concentrations of ozone in ambient air are elevated.

A personal decision to limit outdoor activities should consider more than ozone levels because there are other conditions that can increase health risks, such as high heat and humidity.

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