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-- 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 three 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 in 1970, the region still lacks a complete State
Implementation Plan for complying with National Ambient Air Quality Standards
for ozone, the only pollutant for which the area is in nonattainment.
Ozone
Ozone nonattainment
The eight-county Houston/Galveston region currently fails to meet the NAAQS only for ground-level ozone. There are two ozone stan-dards currently in effect: ozone may not exceed
0.12 parts per million (ppm) averaged over onehour and it may not exceed 0.08 ppm averaged over eight hours. Ozone concentration in the Houston/Galveston region is measured by more than two dozen city, state, and private air moni-toring stations in five counties, operating seven days a week, twenty-four hours a day.
Ozone formation
Ozone is a highly unstable molecule com-posed of three oxygen atoms.
Confusion sometimes arises because ozone is found
at two levels of the earth's atmosphere. The layer of ozone in the stratosphere
(six to thirty 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 six miles above the earth's surface) and
at background levels probably benefits plants and animals, possibly assisting
biosystem purification. 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
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of the Houston Ship Channel, where the region's most hazardous ozone plumes
typically form, found that 75% of the ozone formation potential could be attributed
to industrial sources, 8% to trees and plants, and the remaining 17% to all
other sources, including vehicles, gas stations, and equipment.
Houston's coastal climate affects ozone levels. Warm, sunny days with calm winds
are necessary for ozone to reach unhealthy levels. Depending upon weather conditions,
ozone can reach very hazardous levels in central Houston, or be stretched out
at levels that are only unhealthy for over a hundred miles. Fortunately, because
of the lack of mountains and the presence of frequent sea breezes, Houston's
pollution does not accumulate the way it can in cities such as Los Angeles.
Rather than long periods of gradually increasing pollution levels, Houston manages
to reach similarly hazardous pollution levels in just a day or two - but the
air sometimes clears up just as quickly.
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.
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. Under current regulations, the Houston-Galveston area must attain the standard for ground-level ozone by 2007 or face sanctions.
In December 2000, TCEQ submitted its most recent version of the State Implementation
Plan to reduce ground level ozone. Control measures in the document included
reducing industrial NOx emissions by 90 percent, lowering the speed limit in
the eight-county region to 55 miles per hour, banning the use of construction
and commercial lawn equipment between 6 a.m. and noon (prime ozone formation
hours), increasing vehicle inspection requirements, and introducing low sulfur
gasoline. Visit www.tceq.com for a detailed list of controls.
Although implementation of the plan will si-nificantly reduce ozone levels, it
does not yet contain sufficient NOx reductions to meet federal standards.
EPA approved the plan despite the fact that it falls short of necessary NOx
reductions by 56 tons per day. The agency accepted the state's proposal to
conduct a mid-course review. Business groups and environmental organizations
filed a lawsuit claiming the SIP violates the Clean Air Act, but the suit did
not succeed in the U.S. Fifth Circuit Court.
Carbon Dioxide
In 2003, environmental groups called attention to the impact of Houston industry
on climate change. Several local companies rank among the worst in the nation
when it comes to carbon dioxide emissions. Carbon dioxide is a greenhouse gas
commonly blamed for global warming. The effects of global warming could be
felt dramatically in Houston where the coastline sinking and the sea level
rising, flooding and subsidence are major concerns. Along with climate change
comes an increased intensity of tropical storms.
Particulate Matter
Particulate matter (microscopic solid or aerosol particles suspended
in the air) may incorporate water and a wide variety
of inorganic salts, acids, metals, organic compounds,
and soot-like material. The NAAQS for particles that
are 10 microns or smaller in diameter 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. Houston
began monitoring PM2.5 in 1999.
Health effects of particulate matter
Various studies have linked increased morbidity and mortality (respiratory
illnesses, heart attacks, and early death) to elevated levels of PM10,
most recently a national study by a team of researchers at Johns Hopkins
University in Maryland. Some particulates have been shown to be carcinogenic
as well. A study by the Boston-based Clean Air Task Force credited particulate
matter produced by power plants with 201 premature deaths annually in
the Houston region.
Air Toxics
Air toxics are chemicals known to increase the risk of cancer, immune
and neurological damage, reproductive and endocrine
disorders, and birth defects. 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 listed in the Clean Air Act.
The EPA has not established NAAQS for the HAPs, but does limit emissions
from spe-cific sources. Industry is also required to report the levels
of 654 toxic chemicals and metals that it releases. The Toxic Release
Inventory for 2000, which compiles this data, ranks Harris County as second
in the United States with more than 24 million pounds of toxic air emissions.
However, recent studies have shown that the chemical plants and refineries
in the Houston area are releasing six to fifteen times more of certain
pollutants than they are reporting, and the official emissions inventories
have not been adjusted to account for this massive underreporting.
Recent Progress
Attitudes
Though air quality in the Houston area has changed little over the
past decade, attitudes 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 SIP deadlines, has motivated business and industry
leaders, and state and city elected officials, to join environmentalists
in the struggle for cleaner air. Throughout 2003 city elections, polls
indicated air quality was a top, if not the number-one concern among voters.
City of Houston efforts
The City of Houston has initiated a compre-hensive 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 by taking the lead in air quality improvement. Among the first steps taken by the city are the use of a lower-emission diesel fuel, purchase of hybrid and other low-emission vehicles, and retrofitting some diesel vehicles to reduce emissions.
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 use-ful 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 http://ozone.hcoem.org/ 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 TCEQ at (713) 767-3500, especially when the source of pollution is unknown but strong odors or respiratory symptoms suggest that pollution is present.
Report polluting automobiles to TCEQ'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. TCEQ 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.
Consume less: The manufacture, transportation, use, and disposal of consumer goods produces air pollution; making wise purchases can improve air quality.
Purchase green power wherever it is available.
