Ozone 101

What is Ozone?

ozone molecule
Ozone is a molecule comprised of three oxygen atoms instead of the two atoms that gaseous oxygen usually contains. When it is present in the air at ground level, ozone is the main component of the type of air pollution referred to as smog. According to the Texas Commission on Environmental Quality (TCEQ), ground-level ozone is the most common air pollutant in Texas and the nation.

Ozone is not emitted directly into the air by any one pollution source, but is formed through chemical reactions between natural and man-made emissions of volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight. These gaseous compounds mix in the air, and when they interact with sunlight, ozone is formed. Sources of VOC and NOx pollutants include automobiles, gas-powered engines, refineries, chemical manufacturing plants, solvents used in dry cleaning and paint, and wherever natural gas, gasoline, diesel fuel, kerosene, and oil are used as fuel.

Ozone pollution is mainly a daytime problem during summer months because warm temperatures and sunlight play a role in formation of high ground-level ozone. For the San Antonio region, the ozone season is from March through November, when temperatures are at their highest and the days are longest. During high temperatures, when the sunshine is strong and winds are weak, ozone can build up to harmful levels.

Isn’t Ozone Good for Us?

Good and Bad Ozone
The word ozone creates confusion because it can be either helpful or harmful, depending on where it is located. Ozone occurs in two layers of the atmosphere. Up high in the earth’s atmosphere, ozone protects us from the sun’s harmful ultraviolet rays. Down low, in the air we breathe, ozone can negatively impact human and animal health and damage vegetation.

Ozone can irritate breathing passages and cause shortness of breath, wheezing, and coughing. It can cause or make respiratory illnesses such as asthma worse. Individuals most susceptible to ground-level ozone are children (whose lungs are still developing), those who already have respiratory ailments such as asthma or emphysema, and those who work or exercise strenuously outside for extended periods of time.

What Can We Do About It?

The Texas Commission on Environmental Quality (TCEQ) forecasts days when conditions are likely to produce high levels of ozone. TCEQ encourages people to take voluntary action on those days to both reduce pollution and protect their health.

Since automobiles are a major culprit in ozone formation in our region of Texas, it is helpful to limit our driving on Ozone Action Days, when ozone pollution is predicted to be high. Actions like carpooling, riding the bus, riding a bicycle, combining errands, avoiding rush hour traffic, and packing a lunch to eat in rather than going out can all help reduce air pollution. Waiting to refuel our vehicles or mow our lawns until after 6:00 p.m. can also be helpful.

While such actions are particularly important on Ozone Action Days, our daily choices are also important in improving air quality. Below are some actions that not only improve the air but also save gas money:

  • Share a ride to work or school instead of driving alone
  • Walk or bike—especially for trips of a mile or less
  • Avoid lunch-time trips–take your lunch to work or school
  • Combine errands into one trip
  • Drive the speed limit or less
  • Avoid waiting drive-through lanes—go inside instead
  • Keep your vehicle properly tuned and your tires properly inflated for improved gas mileage

Businesses can also help improve the air by:

  • Shifting work schedules to help employees avoid rush-hour traffic
  • Allowing employees to telecommute (work from home)
  • Offering reimbursement for bus passes
  • Encouraging employees to carpool to lunch and meetings;
  • Scheduling meetings that don't require driving (for example, teleconferencing)
  • Offering incentives, such as premium parking spaces, for employees who carpool