News Release


Protection From Ozone-Related Respiratory Problems Only a Fresh Smell Away


People can smell their way out of ozone trouble.

Alerts notifying residents of unhealthy levels of ozone in the Houston-Galveston area are issued after monitoring equipment performs high-tech tests on outdoor air, but people can carry out similar type of readings for the pollutant, a cause of numerous respiratory health problems.

Learning to recognize what ozone smell like enables people to make educated decisions about limiting the time spent outdoors being physically active to avoid ozone exposure, especially harmful to those with respiratory diseases, children and the elderly.

"Ozone is the fresh smell you can detect during and after a thunderstorm," said Gene McMullen, assistant bureau chief at the Houston Department of Health and Human Servicesí Bureau of Air Quality Control. "Office machines such as copiers and laser printers generate electric fields that also produce a small amount of ozone that you can easily smell."

McMullen said recognizing ozone gives people a head start since it takes an hour and a half to two hours for information on pollution levels to become available through the internet or the news media.

A gas composed of three atoms of oxygen, ozone occurs naturally in the Earthís atmosphere and creates a shield against the sunís ultraviolet rays. It also forms at ground level when emissions by cars, power plants, refineries, chemical plants and other sources react chemically with sunlight.

Unhealthy levels of ground-level ozone typically form in the afternoon during the hot summer months when sunny days with high temperatures and low wind speeds are more common, McMullen said.

"Ozone can cause or aggravate several respiratory health problems, some of which may result in emergency room visits or hospital admissions during or a few days after high levels of exposure," said Dr. Nick Hanania, a Baylor College of Medicine pulmonologist conducting a study exploring the correlation between pollutants and emergency room visits to Ben Taub General Hospital by adult asthmatics. Hanania, who used statistical air quality data provided by the Bureau of Air Quality Control, said ozone-related respiratory problems include:

  • Irritation of the respiratory system. Symptoms include coughing, throat irritation or an uncomfortable sensation in the chest; they may last a few hours and become painful.
  • A reduction in lung function. Ozone can make it more difficult to breathe deeply and vigorously. If exercising or working outside, people may notice they are taking more rapid and shallow breaths than normal, a problem for outdoor workers.
  • Exacerbation of asthma. Ozone makes people more sensitive to allergens and when the pollutant reaches high levels, more asthmatics have asthma attacks requiring a doctorís attention or use of additional medication. Also, asthmatics are more severely affected by the reduced lung function and irritation that ozone causes in the respiratory system.
  • Inflammation and damage of lung tissue. Ozone damages the cells that line the air spaces in the lung. Affected cells are replaced after a few days, but if damage occurs repeatedly, the lung may change permanently and possibly cause long-term health effects and lower quality of life.

Dr. Hanania, who is also director of Baylor's Asthma Clinical Research Center, said groups most at risk to harmful ozone exposure are children because they often engage in vigorous outdoor activities, adults who are active outdoors, people with respiratory diseases such as asthma and those with unusual susceptibility to ozone.

Information on local ozone levels is available from the Bureau of Air Quality Control by calling 713-640-4358. The recorded statement provides callers the daily air quality index, which is divided by Environmental Protection Agency into five categories: good, moderate, unhealthy for sensitive groups, unhealthy and very unhealthy.

No health impacts are expected in the good category. However, the moderate category warns unusually sensitive people to consider limiting prolonged outdoor exertion. The unhealthy for sensitive groups category alerts active children and adults and people with respiratory disease to limit prolonged exertion.

The unhealthy and very unhealthy levels notify everyone, especially active children and adults and people with respiratory disease, to limit prolonged exertion.

The Bureau of Air Quality Control is responsible for air quality issues within Houstonís city limits. It enforces federal and state air pollution regulations, operates and maintains an ambient air-monitoring network and enforces Houstonís air pollution registration ordinance.

Information on ozone watches and warnings are available through the Houston Department of Health and Human Services web site, An ozone watch indicates conditions likely to form high levels of ozone while an ozone warning reports that levels which have exceeded the federal health standard.