Our Blog

Wednesday, June 11, 2014

Asthma: A major ozone-related health concern in the Houston area

Ozone and Asthma

Breathing ozone triggers a variety of health problems

"Asthma spacer" by Tradimus, licensed under CC BY 3.0

Health concerns lie at the heart of Houston’s decades of attention to ground-level ozone and the air pollutants from sources including industries and cars that form it in chemical reactions on sunny days.

The U.S. Environmental Protection Agency summarizes those concerns:

Breathing ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ground level ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue.

With regard to ozone and asthma – the particular health condition that inspired faculty members at the University of Houston to begin planning the Houston Clean Air Network’s online ozone-mapping tools – the EPA says this:

Patients with pre-existing respiratory diseases are potentially at increased risk of adverse effects of ozone exposure because the response to ozone may interact with the pathophysiology of the underlying disease or simply because these patients generally have less pulmonary reserve and cannot tolerate the reduction in lung function or the increase in symptoms.

On days with high ozone levels, people with asthma can experience these symptoms, including these, the EPA adds:

"... 96,000 children and 186,000 adults in Harris County have been diagnosed with asthma. Asthma is the third leading reason for children under 15 being hospitalized and contributes significantly to school absenteeism,"

--2012 Report, "The State of Health in Houston/Harris County

  • Lung function decrements.
  • Increased respiratory symptoms.
  • Increased medication usage.
  • Increased frequency of asthma attacks.
  • Increased use of health care services.

Local health officials and other health experts examined asthma among 14 “health indicators” in a 2012 report, The State of Health in Houston/Harris County.

The report said 96,000 children and 186,000 adults in Harris County have been diagnosed with asthma. Asthma is the third leading reason for children under 15 being hospitalized and contributes significantly to school absenteeism, the authors added.

One of the recommended public health actions in the report, pertinent to the Network’s ozone map, was: “Inform, educate, and empower people about asthma through publications, trainings, and other media.”

While that report focused on Harris County, a Houston Chronicle investigation in 2011 examined asthma in outlying counties of the Houston region, finding that a number of rural areas had “significantly elevated hospitalization rates.”

Nearly 10,000 people in a 10-county Houston region were hospitalized for asthma from 2007-09, according to state data, the newspaper reported.

The Chronicle said experts attrib added: “Experts attribute higher hospitalization rates in rural areas mainly to one factor: “Urban areas, with more health care options, are better equipped to treat the respiratory disease that kills almost 4,000 people and puts 456,000 Americans in hospitals every year.”

The Chronicle found that Liberty County, north of Houston, has the highest rate of hospitalization for asthma-linked conditions in the 10-county health region surrounding the city. Liberty county is also included in the eight-county “non-attainment area” for ozone – the area officially designated as violating the federal health standard for ozone.

A report commissioned during the tenure of former Houston Mayor Bill White, who held the city’s top office for three terms from 2004-2010, examined asthma’s connections to air pollution among other air quality topics.

The report, “A Closer Look at Air Pollution in Houston: Identifying Priority Health Risks,” was produced by the Mayor’s Task Force on the Health Effects of Air Pollution,” which was convened by the Institute for Health Policy at the University of Texas School of Public Health.

The panel’s asthma-related conclusions indicated that its concerns extended to pollutants other than ozone in addition to ozone itself:

  • “In general, as concentrations of ground-level ozone increase, more and more people experience health effects and the effects become more severe. Common symptoms of ozone exposure include mild irritation of the throat, difficulty breathing and chest tightness. … Several groups of people are particularly sensitive to ozone exposure. These groups include: active children, active adults of all ages, people with asthma or other respiratory dis- eases and people with unusual susceptibility to ozone.”
  • “Repeated daily short-term exposure to ozone can cause an increased response to bronchial allergen challenges in subjects with preexisting allergic airway disease, with or without asthma.”
  • “Short-term exposures (minutes to hours) [to tiny particles in diesel exhaust] may cause eye, throat, and bronchial irritation, lightheadedness, nausea, cough, and phlegm, as well as exacerbation of allergic responses and asthma-like symptoms.”
  • On typical “smoggy” days in Houston, residents can be exposed to “a complicated mix” of air pollutants, including ozone, particles and hundreds of others. “Depending on exposure and other factors, even healthy adults may suffer acute or chronic effects from this air pollution miasma. But those most likely to be affected are the elderly, particularly those with lung and heart disease, children and adults with asthma, chronic obstructive pulmonary disease or other respiratory illnesses, individuals with cardio-vascular disease, pregnant women and their fetuses, and children in general because, compared to adults, they inhale more air per kilogram of body weight, breathe more rapidly, and tend to breathe through their mouth more often.”