Ozone 9 Get Into Pc

[Keesha Ondieki]

Calledstratospheric ozone, good ozone occurs naturally in the upper atmosphere, where it forms a protective layer that shields us from the sun's harmful ultraviolet rays. This beneficial ozone has been partially destroyed by manmade chemicals, causing what is sometimes called a "hole in the ozone." The good news is, this hole is diminishing. Learn more about stratospheric, or "good" ozone.

Tropospheric, or ground level ozone, is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC). This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight.

Ozone is most likely to reach unhealthy levels on hot sunny days in urban environments, but can still reach high levels during colder months. Ozone can also be transported long distances by wind, so even rural areas can experience high ozone levels.

Ozone in the air we breathe can harm our health, especially on hot sunny days when ozone can reach unhealthy levels. People at greatest risk of harm from breathing air containing ozone include people with asthma. Learn more about health effects.

Elevated exposures to ozone can affect sensitive vegetation and ecosystems, including forests, parks, wildlife refuges and wilderness areas. In particular, ozone can harm sensitive vegetation during the growing season. Learn more about how ozone harms ecosystems.

Air quality forecasts are often given with weather forecasts on handheld devices, online or in the paper or television. You can check ozone levels and other daily air quality information by visiting www.airnow.gov and in many areas you can receive air quality notifications through www.enviroflash.info.

There are national ambient air quality standards (NAAQS) for each of the criteria pollutants. These standards apply to the concentration of a pollutant in outdoor air. Learn more about criteria air pollutants and NAAQS.

After working with the states and tribes and considering the information from air quality monitors, EPA "designates" an area as attainment or nonattainment with national ambient air quality standards. If the air quality in a geographic area meets or does better than the national standard, it is called an attainment area; areas that don't meet the national standard are called nonattainment areas. Learn more about ozone air quality designations.

In order to improve air quality, states must draft a plan known as a state implementation plan (SIP) to improve the air quality in nonattainment areas. The plan outlines the measures that the state will take in order to improve air quality. Once a nonattainment area meets the standards, EPA will designate the area as a "maintenance area."

People most at risk from breathing air containing ozone include people with asthma, children, older adults, and people who are active outdoors, especially outdoor workers. In addition, people with certain genetic characteristics, and people with reduced intake of certain nutrients, such as vitamins C and E, are at greater risk from ozone exposure.

Children are at greatest risk from exposure to ozone because their lungs are still developing and they are more likely to be active outdoors when ozone levels are high, which increases their exposure. Children are also more likely than adults to have asthma.

Some of these effects have been found even in healthy people, but effects can be more serious in people with lung diseases such as asthma. They may lead to increased school absences, medication use, visits to doctors and emergency rooms, and hospital admissions. Some studies in locations with elevated concentrations also report associations of ozone with deaths from respiratory causes.

Some devices that are advertised as air purifiers purposely emit large amounts of ozone, the main component of smog. CARB recommends that ozone generators not be used, except for approved industrial purposes where harmful exposure to ozone is prevented. Not only are ozone generators ineffective at cleaning indoor air, but inhaling ozone poses serious health risks for humans and animals. This fact sheet discusses these health risks and provides effective, alternative solutions to address indoor air quality problems.

Air cleaners that utilize ionizers and electrostatic precipitators are other types of devices that emit ozone, but do so as a by-product of their design and function. These devices are designed to electrically charge particles in the air and cause them to attach to surfaces in the room, such as walls or floors. Ozone is released through the charging process, although these devices typically emit much less ozone than ozone generators.

Ozone generators can produce indoor ozone levels several times higher than the State's outdoor 1-hr and 8-hr health standards of 90 parts per billion (ppb) and 70 ppb respectively. Many commercial ozone generators emit more than 5,000 mg of ozone per hour of operation, which could result in unhealthy levels of ozone in indoor air.

People who buy ozone generators may not be aware that ozone can harm the cells in the lungs and respiratory airways. Exposure to ozone irritates and inflames the lining of the respiratory system. This causes symptoms including coughing, chest tightness, shortness of breath, and impaired breathing. Ozone can worsen asthma symptoms, and may contribute to the development of asthma. Elevated exposures to ozone can cause permanent lung damage, and repeated exposure can even increase the risk of dying among persons already in poor health. Persons especially vulnerable to health problems from breathing ozone include children and those who already suffer from asthma or other respiratory diseases, including the elderly. There are many experimental studies on animals, including dogs, cats, hamsters and guinea pigs, that show respiratory effects from exposure to ozone. Birds are especially sensitive to the effects of air pollutants, including ozone.

The unfortunate answer is that misleading advertising by manufacturers is very effective, and no government agency has the authority to fully regulate these devices. Thus, CARB is actively working to educate professionals and the public about the dangers of using ozone generators.

CARB strongly advises against the use of ozone generators in spaces occupied by people or animals. Other governmental agencies agree with this advice. CARB provides a list of potentially hazardous ozone generators sold as "air purifiers", which is periodically updated. If an ozone generator is not on this list, it does not mean that it is safe for use.

Prior to purchasing an air cleaner, consumers are encouraged to eliminate or reduce indoor pollution sources and to ventilate areas with outdoor air. The most effective method of controlling indoor air pollution is through prevention: eliminating pollution at its source. To minimize the release of pollutants indoors:

Use plenty of ventilation: be sure there is adequate airflow to/from the outdoors. This can be achieved by opening windows, using exhaust fans near pollutant sources (e.g. above stoves while cooking), and increasing airflow through the use of mechanical ventilation systems. If your home is equipped with a central forced air system, you should also consider upgrading the filter to at least MERV 13.

In 2007, CARB adopted a regulation to limit ozone emissions from indoor air cleaning devices. Over 300 manufacturers have submitted test results and obtained CARB certification of their air cleaning devices as required under our regulation. Certification is based on a device's low (usually near-zero) ozone emissions and electrical safety. The following information provides the list of CARB certified air cleaning devices and additional information on how to choose a safe and effective air cleaner.

In the stratosphere, ozone is created primarily by ultravioletradiation. When high-energy ultraviolet rays strike ordinary oxygenmolecules (O2), they split the molecule into two single oxygen atoms,known as atomic oxygen. A freed oxygen atom then combines with anotheroxygen molecule to form a molecule of ozone. There is so much oxygen inour atmosphere, that these high-energy ultraviolet rays are completelyabsorbed in the stratosphere.

Ozone is extremely valuable since it absorbs a range ofultraviolet energy. When an ozone molecule absorbs even low-energyultraviolet radiation, it splits into an ordinary oxygen molecule and afree oxygen atom. Usually this free oxygen atom quickly re-joins with anoxygen molecule to form another ozone molecule. Because of this"ozone-oxygen cycle," harmful ultraviolet radiation is continuouslyconverted into heat.

Natural reactions other than the "ozone-oxygen cycle" describedabove also affect the concentration of ozone in the stratosphere.Because ozone and free oxygen atoms are highly unstable, they react veryeasily with nitrogen, hydrogen, chlorine, and bromine compounds that arefound naturally in Earth's atmosphere (released from both land and oceansources). For example, single chlorine atoms can convert ozone intooxygen molecules and this ozone loss balances the production of ozone byhigh-energy ultraviolet rays striking oxygen molecules.

In addition to the natural ozone balance, scientists have foundthat ozone levels change periodically as part of regular natural cyclessuch as the changing seasons, winds, and long time scale sun variations.Moreover, volcanic eruptions may inject materials into the stratospherethat can lead to increased destruction of ozone.

Over the Earth's lifetime, natural processes have regulated thebalance of ozone in the stratosphere. A simple way to understand theozone balance is to think of a leaky bucket. As long as water is pouredinto the bucket at the same rate that water is leaking out, the amountor level of water in the bucket will remain the same. Likewise, as longas ozone is being created at the same rate that it is being destroyed,the total amount of ozone will remain the same.

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