Air Quality

The Houston-Galveston region is home to the largest oil refining and chemical manufacturing complex in the United States, with the consequence that air pollution – defined as the presence of gases and particles in the air that adversely affect the health or comfort of humans and animals, or that damage plants and materials[i] – continues to be an important environmental concern. Numerous public and private power plants also contribute heavily to area air pollution, as do the more than 3 million vehicles currently on the road in this region. Add the activity of the Port of Houston, our two major airports, and many smaller air pollution sources associated with the bustle and boom of urban life, and the result is a many-dimensioned problem.

Although substantial progress has been made since the passage of the federal Clean Air Act (CAA) in 1970, the region still lacks a complete State Implementation Plan (SIP) for complying with National Ambient Air Quality Standards for ozone, the only pollutant for which the area is in nonattainment. The current SIP, approved by the US Environmental Protection Agency (EPA) in October 2001, falls short of attainment by 56 tons of nitrogen oxide (NOx) emissions per day, according to modeling by the Texas Natural Resource Conservation Commission (TNRCC). TNRCC, which developed the plan, has promised to add additional emission controls at a future time.

Air Quality Standards

The Clean Air Act of 1970, significantly amended in 1990, required the U.S. Environmental Protection Agency (EPA) to study the effects of ambient (outdoor) air pollution and establish appropriate air quality standards for communities to meet within certain timeframes.

National Ambient Air Quality Standards (NAAQS) have been developed for six categories of air pollution: ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen dioxide, particulate matter, and lead. For each of these pollutants, the EPA has established primary standards intended to protect public health and secondary standards intended to protect public welfare by preventing plant and property damage.

Ozone

Ozone nonattainment

The eight-county Houston-Galveston region currently fails to meet the NAAQS only for ground-level ozone. The primary and secondary standard for ozone is 0.12 parts per million (ppm) averaged over one hour. Ozone concentration in the Houston-Galveston region is measured by 25 city, state, and private air monitoring stations in five counties, operating seven days a week, 24 hours a day. In 1999 and 2000, the Houston region led the country in the number of days on which at least one monitor exceeded the federal standard, and had the single highest one-hour ozone reading in the United States. Due to cool and windy weather patterns in the area in 2001, the title of “smog capital” was handed back to Los Angeles, which experienced 36 ozone exceedences compared with the Houston-Galveston region’s 32. 

Ozone formation

Ozone is a highly unstable form of oxygen composed of three oxygen atoms (O₃). Confusion sometimes arises because ozone is found at two levels of the earth’s atmosphere. The layer of ozone in the stratosphere (6 to 30 miles above the earth’s surface) protects the earth by absorbing ultraviolet rays from the sun. It is this protective layer of ozone that is being damaged by human activity.

Ground-level ozone is a corrosive gas and a principal component of smog. It forms naturally in the troposphere (up to 6 miles above the earth’s surface) and at background levels probably benefits plants and animals, possibly important for biosystem purification.[ii] But at the higher concentrations resulting from human activity, ground-level ozone is known to harm humans, animals, and plants.

Ground-level ozone is not emitted directly; rather it is produced by a series of chemical reactions involving nitrogen oxides (NOx), volatile organic compounds (VOCs), and sunlight.

Nitrogen oxides are largely a product of high-temperature combustion. Fifty-five percent of the region’s NOx is produced by stationary point sources (industrial, commercial), 24 percent by on-road mobile sources (vehicles), and 20 percent by non-road mobile sources (aircraft, boats, trains, lawn equipment), according to the 1996 Periodic Emission Inventory prepared by the Texas Natural Resource Conservation Commission (TNRCC).

Volatile organic compounds are a wide range of chemicals that vaporize easily. Common sources include industry, vehicles and equipment, gas stations, paint, and biogenic emissions from trees and plants. Again according to the Periodic Emissions Inventory, stationary point sources release 31 percent of local human-made VOC emissions, area sources (non-mobile sources that emit less than the stationary point source definition) release 25 percent, on-road mobile sources release 24 percent, and non-road mobile sources release 20 percent. Because VOC sources vary greatly, and are therefore more difficult to control, NOx has been labeled the limiting factor in ozone formation and is the focus of the most recent ozone reduction strategies.

Ozone levels are exacerbated by Houston’s coastal climate; sunny days, low wind speeds, and elevated temperatures increase ozone formation. Ozone exceedances can occur quite far from NOx and VOC sources depending upon weather and wind patterns and mixing heights.

Health effects of ozone

Ozone can cause or aggravate respiratory problems. Exposure may compromise the immune system, making people more susceptible to respiratory infection. Breathing ozone may also increase the severity of asthma and asthma attacks. Prolonged exposure may lead to permanent scarring and premature aging of the respiratory system.[iii]

The State Implementation Plan (SIP)

The EPA requires the state agencies that oversee nonattainment areas to submit plans outlining the steps that will be taken to attain the National Ambient Air Quality Standards within a certain timeframe. Under current regulations, the Houston-Galveston area must attain the one-hour ozone standard by 2007 or face sanctions.

The TNRCC turned in its original State Implementation Plan (SIP) for the eight-county Houston-Galveston area in 1973. The SIP has been revised several times over the years, and the most recent version was approved by the EPA in October 2001. Although the controls in the early plans were successful in decreasing human-made VOC emissions, little progress was made in reducing ground level ozone. New modeling techniques indicate that decreasing NOx emissions by 65 to 85 percent will be necessary to meet the NAAQS; this strategy is reflected in more recent versions of the SIP.

Particulate Matter

The term particulate matter (small particles suspended in the air) includes a wide variety of inorganic salts, acids, metals, water, organic compounds, and soot-like material. The NAAQS for particles that are 10 microns or smaller in diameter (PM₁₀) is 150 micrograms per cubic meter of air averaged over 24 hours, and 50 micrograms per cubic meter averaged over one year. The region is in compliance for PM₁₀ but may not be able to comply with a newer standard for very fine particles smaller than 2.5 microns in diameter (PM_2.5). Houston began monitoring PM_2.5 in 1999.

Health effects of PM₁₀

Various studies have linked increased morbidity and mortality (respiratory illnesses, heart attacks, and early death) to elevated levels of PM_10, most recently a national study by a team of researchers at Johns Hopkins University in Maryland.[iv] Some particulates have been shown to be carcinogenic as well.[v] A recent, although somewhat controversial, study by Boston-based Clean Air Task Force credited particulate matter produced by power plants with 201 premature deaths annually in the Houston region.[vi]

Air Toxics

Air toxics are chemicals known to increase the risk of cancer, immune and neurological damage, reproductive and endocrine disorders, and birth defects.[vii] Sources include industry, vehicles, combustion, pesticide use, dry cleaners, and building materials. Air toxics can be any hazardous chemicals or metals, but the term usually refers to the 188 Hazardous Air Pollutants (HAPs) listed in the Clean Air Act. The EPA has not established NAAQS for HAPs, but does limit emissions from specific sources. Industry is also required to report the levels of 654 toxic chemicals and metals that it releases; the Toxic Release Inventory (TRI) for 1998, which compiles this data, ranks Harris County as having the second highest toxic air emissions in pounds in the United States.

Recent Progress

Attitudes

Attitudes concerning air quality are beginning to evolve. Many stakeholders now realize that air pollution affects all aspects of the region’s health, including economic development. Houston’s reputation as the nation’s smog capital impacts the region’s ability to attract and retain qualified workers. This realization, along with increased pressure from recent SIP deadlines, has motivated business and industry leaders, and state and city elected officials, to join environmentalists in the struggle for cleaner air. For example, the Greater Houston Partnership, the region’s chamber of commerce, has organized the Business Coalition for Clean Air (BCCA), which says it is “committed to improving the air quality in the eight-county Houston-Galveston region and the region's continued economic growth.” In 2001, the BCCA sponsored an advertising campaign to encourage everyone to help clean the air, although some of its member groups are suing to have certain controls removed from the SIP that they see as too stringent on industry.

State Implementation Plan (SIP)

In October 2001, the EPA approved TNRCC’s most recent version of the State Implementation Plan to meet federal standards for ground level ozone by 2007. Control measures in the document include reducing industrial NOx emissions by 90 percent, lowering the speed limit in the eight-county region to 55 miles per hour, increasing vehicle inspection requirements, and introducing low sulfur gasoline. Visit www.tnrcc.state.tx.us for a detailed list of controls.

Although implementation of the plan will significantly reduce ozone levels, it does not yet contain sufficient NOx reductions to meet federal ozone standards. The EPA will allow TNRCC to develop additional controls by 2004 to cut the extra 56 tons of NOx per day needed, a concession that environmental groups think unnecessarily delays the process and breaches the Clean Air Act, which requires that a complete plan be approved by 2001. Environmental groups are also concerned that implementing the current SIP will not be enough to attain federal standards because the plan lacks complete modeling and relies too heavily on unmeasurable emissions reductions. Several environmental organizations and citizens are suing the EPA over the SIP, saying it has been so weakened by industry pressure tactics that it fails to protect public health.

Legislative victories

Air quality advocates saw several victories during the recent 77th Texas Legislature. HB 2912, which authorized the continuation of TNRCC, created a new regulatory scheme for TNRCC that gives flexibility to industry with proven track records and is tougher on chronic rule breakers. The bill requires TNRCC to consider the cumulative impacts of pollution when issuing new permits. Steps were also taken to improve the credibility of the contested case process, allowing citizens a bigger say in the permitting process. Citizen gathered evidence now will be permitted in the enforcement process as well.

Besides reforming TNRCC, HB 2912 established stronger industry requirements for unexpected pollution releases and closed the “grandfather” loophole. The grandfather loophole exempted older plants – those established before the 1970 Clean Air Act – from the standard environmental permitting process. Under this new legislation, all grandfathered facilities in the state must install equipment that conforms to a 10-year-old standard of “Best Available Control Technology” (BACT) by 2008.

SB 5, also passed during the recent session, provides a variety of incentives to retrofit equipment and purchase low-emission vehicles. Because it establishes a voluntary program, it is difficult to predict what the real impact of this potentially significant bill will be.

City of Houston efforts

The City of Houston has initiated a plan to reduce NOx emissions by 75 percent. Although the City contributes only about 0.5 percent of regional NOx, the plan is intended to show good will and take the lead in air quality improvement. Some environmentalists are concerned, however, that many measures in the plan have yet to be implemented.

Texas 2000 Air Quality Study

TNRCC and others undertook the Texas 2000 Air Quality Study, the largest air quality study ever done in the state. Data collection was completed in September 2000; researchers are now beginning to share preliminary results about how air pollution forms and travels along the Gulf Coast and southeastern Texas. For an outline of study results, visit www.ghasp.org/taqs.html.

Citizen air monitoring

Several grassroots organizations, including the Texas Bucket Brigade and Mothers for Clean Air, have begun taking and analyzing air samples in simple bucket and canister devices. Citizen air monitoring can be used to educate the public on air quality issues and to catch polluters.

What You Can Do

Educate yourself

The Air Quality Reference Guide, produced and updated annually by the Houston-Galveston Area Council, provides additional information on local air quality issues and a useful list of actions every citizen can take to improve air quality. Call (713) 993-4577 for a free copy or download the document from www.hgac.cog.tx.us/air/resources.html.

Change activity patterns during peak ozone concentrations

The EPA established an Air Quality Index that recommends restricting activity during peak ozone concentrations. To receive daily ozone-level updates by email or fax, register with the Harris County Office of Emergency Management at www.hcoem.org/oem/subscribe_to_ozone_alerts.htm or call the City of Houston at (713) 640-4358.

Report polluters

Report air pollution from a known source within the city limits to the City of Houston Bureau of Air Quality at (713) 640-4358. Reports can also be made to Harris County Pollution Control at (713) 920-2831 and the TNRCC at (713) 767-3500, especially where the source of pollution is unknown but strong odors or respiratory symptoms suggest that pollution is present.

Report polluting automobiles to TNRCC’s Smoking Vehicle program at (800) 453-7664. Include a description of the automobile, the license plate number, and the date, time, and location of the incident. TNRCC will notify the owner that the automobile may be contributing to air pollution and provide information on rectifying the situation.

Reduce your contribution

-         Use alternative transportation: walk, ride your bike, take the bus, or carpool. Consider buying an electric hybrid or other low emission car rather than an SUV.

-         Consume less: The manufacture, transportation, use, and disposal of consumer goods produces air pollution; making wise purchases can improve air quality.

-         Energy: Texans may now purchase 100 percent wind power from Green Mountain Energy, currently the region’s only green electricity provider (see the Electricity section).

This section was taken from the State of the Environment 2002, the introduction to the 2002 Environmental Resource Guide, produced by the Citizens' Environmental Coalition (CEC). The above statements do not necessarily reflect the opinions of CEC, its trustees, officers, or staff.