Summer Air Pollution Season Receives Good Marks

News Release

For Immediate Release

Contact:    Beth Gorman    (520) 740-3343

Tucson, Arizona (October 16, 2007) – According to air pollution monitoring data from Pima County Department of Environmental Quality, levels of air pollution were down this summer compared with 2006. There were more days during the summer of 2007 categorized as “good” air quality days and fewer days in the “moderate” categories for ozone and particulate pollution when compared with 2006.

Out of 183 days from April 1 through September 30, 2007, only 39 days were in the “moderate” range for ground-level ozone compared with 50 “moderate” days in 2006. There were no unhealthy days for ozone in 2007 and 2006, compared with one “unhealthy for sensitive individuals” day in 2005. In addition, the highest Air Quality Index (AQI) ozone reading in 2007 (79) was considerably lower than the 2006 maximum reading (97). “It is difficult to pinpoint exactly why ozone levels were lower this summer, but the combination of weather conditions and pollution prevention programs most likely contributed to the reduced formation of ozone,” said Beth Gorman, Program Manager for Pima County Department of Environmental Quality. “On average, our ozone levels are running at about 10 percent below the U.S. Environmental Protection Agency (EPA) health standard, which is a small cushion of safety,” Gorman continued. “And EPA has proposed lowering the health standard to be more protective of public health, so exceedances of the new ozone standard could be in our future,” she said.

Ground-level ozone is created when nitrogen oxides, typically from automobile emissions, combine with volatile organic compounds, such as solvents and gasoline fumes, in the presence of sunlight. This air pollutant that forms at ground-level is not to be confused with the ozone layer which occurs naturally in the upper atmosphere and protects us from damaging solar radiation. The AQI uses a formula to translate the pollutant concentration into an index value from 1 to 500, where 1-50 is good, 51-100 is moderate, and over 100 is considered various stages of “unhealthy” all the way to “hazardous” at 500.

The AQI levels for another air pollutant called particulate matter were also lower during the summer of 2007 than during the previous summer. This more visible pollutant is comprised of microscopic particles generated from numerous sources including diesel soot, vehicle emissions, road dust from traffic, unpaved roads, industrial emissions, mining activity, wood smoke, construction activities, farming, and wind-blown soil.

PDEQ recorded 174 “good” days for particulate matter pollution that is 10 micrometers or less in diameter (PM10) during the summer of 2007, compared with 168 in 2006. As with 2005 and 2006, no days were considered “unhealthy” for particulate matter during the summer of 2007. “Elevated levels of particulate matter can occur any time of year, especially when it is dry and windy,” said Wayne Byrd, Manager of the air quality monitoring network at PDEQ. The Pima County area violated the EPA health standards for PM10 in 1999. The Pima County Board of Supervisors adopted stricter fugitive dust control regulations in December 2002.

Changes in levels of solar radiation in the fall and winter months reduce the potential for ozone pollution, but winter weather conditions can increase levels of carbon monoxide (CO). Elevated levels of CO can occur in the winter, when stagnant weather conditions, coupled with reduced engine efficiency associated with colder temperatures, cause higher levels of CO. Other sources of CO include wood fires, barbeques, and gasoline lawn and garden equipment. CO affects human health by entering the bloodstream and inhibiting the blood’s ability to carry oxygen to organs and tissues. After being designated as non-attainment of the EPA CO health standards for violations occurring in the 1970s and early 1980s, Pima County was redesignated by EPA as a CO maintenance area in the spring of 1999. Two seasonal CO monitoring sites began collecting data in early October at Cherry/Glenn and Kolb/Golf Links and will augment data from PDEQ’s four full-time CO sites.

PDEQ is the Air Quality Control District for Pima County and, as such, is the agency responsible for ambient air monitoring. The department monitors five different air pollutants at numerous sites around the county. Site-specific air pollution information can be obtained by calling (520) 882-4AIR or by visiting the PDEQ website at www.AirInfoNow.org.

Air Quality Index Readings
April 1 – September 30

2007	Ozone	PM10
# of Good days	144	174
# of Moderate days	39	9
# of Unhealthy FSG*	0	0
Max AQI Reading**	79	68

2006	Ozone	PM10
# of Good days	133	168
# of Moderate days	50	15
# of Unhealthy FSG*	0	0
Max AQI Reading**	97	72

2005	Ozone	PM10
# of Good days	141	150
# of Moderate days	41	33
# of Unhealthy FSG*	1	0
Max AQI Reading**	106	66

2004	Ozone	PM10
# of Good days	133	177
# of Moderate days	50	6
# of Unhealthy FSG*	0	0
Max AQI Reading**	79	83

2003	Ozone	PM10
# of Good days	133	177
# of Moderate days	50	6
# of Unhealthy FSG*	0	0
Max AQI Reading**	79	83

*Unhealthy For Sensitive Groups
**Maximum Air Quality Index Values

0 to 50	Good	No health effects are expected.
51 to 100	Moderate	Individuals may experience respiratory effects from prolonged outdoor exertion if they are unusually sensitive.
101 to 150	Unhealthy for Sensitive Groups	Members of sensitive groups may experience respiratory symptoms (coughing, pains when taking a deep breath).
151 to 200	Unhealthy	Members of sensitive groups have higher chance of experiencing respiratory symptoms (aggravated cough or pain), and reduces lung function. Everyone else should limit prolonged exertion.
201 to 300	Very Unhealthy	Members of sensitive groups experience increasingly severe respiratory symptoms and impaired breathing and should avoid any outdoor activity. Everyone else should limit prolonged exertion.
301 to 500	Hazardous	Warnings at this level trigger emergency conditions. The entire population is likely to be affected.

Graphs of the Good Air Quality Index Days for Ozone and Particulates

Source - Pima County Department of Environmental Quality

Health Effects of Particulate Matter

When inhaled, particulate matter invades the respiratory system’s natural defenses and lodges deep in the bronchial tubes. Health effects of particulate matter include:

• Premature mortality;
• Chronic respiratory disease;
• Aggravated asthma;
• Acute respiratory symptoms;
• Decreased lung function;
• Reduction in the body’s ability to fight infections.
• 36% increase in death from lung cancer;
• 26% increase in cardiopulmonary deaths;
• Significant increase in hospital and doctors visits; medication use;
• Increase in bronchitis, chronic cough, and respiratory symptoms in persons with COPD; and
• Increase in wheezing and shortness of breath
• Increase in cardio-respiratory mortality and morbidity even when PM is below federal standard

Health Effects of Carbon Monoxide

Carbon monoxide enters the bloodstream and reduces oxygen delivery to the body's organs and tissues. The health threat from exposure to CO is most serious for those who suffer from cardiovascular disease. Depending on the concentration level, health effects of CO include:

• Visual impairment;
• Reduced work capacity;
• Reduced manual dexterity;
• Poor learning ability difficulty in performing complex tasks;
• Fatigue in healthy people;
• Chest pain in people with heart disease;
• Headaches;
• Dizziness;
• Confusion;
• Nausea;
• Flu-like symptoms that clear up after leaving area with elevated CO; and
• Death.

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