SOURCES OF CFCS - Chlorofluorocarbons, also known as CFCs, consist of chemical compounds made up of chlorine, fluorine and carbon. CFCs are particularly harmful when released into the atmosphere because of their destructive reaction with O-zone particles, which provide the Earth with a protective layer against UV radiation. A few specialized products still contain CFCs. The most common source of CFCs are refrigerants, but fire suppression systems for aircraft and aerosols also emit CFCs into the atmosphere. Dupont brand named their new product “Freon” and various other brand names produced the CFC-based refrigerant worldwide. When the coolant used in old refrigerators, cars, air conditioners and other machines is not properly disposed of, it leaks CFCs into the atmosphere as liquids evaporate or work their way into the soil. Aviation regulations in some countries still require fire suppression systems outfitted with Halon, a coolant containing CFCs. There is no safe, effective alternative. The industry must follow certain safety measures to dispose of this dangerous chemical responsibly and to recycle the material when possible. Aerosol cans and propellant liquids used gasses containing CFCs for a long time. They were phased out of aerosol production in 1999 in favor of less harmful hydrocarbon alternatives. However, since CFC molecules have a lifetime of 20 to 100 years in the stratosphere, the damage done in previous decades continues to make an impact. As refrigerants and aerosol cans containing CFCs become older and more obsolete, people tend to forget about them, leaving them to leak and further contaminate the atmosphere.

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Sources of CFCs

What Are the Sources of CFCs?

By Tommy Doc

 

Chlorofluorocarbons, also known as CFCs, consist of chemical compounds made up of chlorine, fluorine and carbon.

CFCs are particularly harmful when released into the atmosphere because of their destructive reaction with O-zone particles, which provide the Earth with a protective layer against UV radiation.

Since 1995 most countries have virtually eliminated CFC production, but a few specialized products still contain CFCs.

TL; DR (Too Long; Didn't Read)

The most common source of CFCs are refrigerants, but fire suppression systems for aircraft and aerosols also emit CFCs into the atmosphere.

Refrigerators and Air Conditioners

The most common emitter of CFCs are refrigerants, particularly those used after the 1930s.

Dupont brand named their new product “Freon” and various other brand names produced the CFC-based refrigerant worldwide.

When the coolant used in old refrigerators, cars, air conditioners and other machines is not properly disposed of, it leaks CFCs into the atmosphere as liquids evaporate or work their way into the soil.

Aircraft Halon

Aviation regulations in some countries still require fire suppression systems outfitted with Halon, a coolant containing CFCs.

As of 2011, there is no safe, effective alternative. The industry must follow certain safety measures to dispose of the this dangerous chemical responsibly and to recycle the material when possible.

Aerosol Sprays

Aerosol cans and propellant liquids used gasses containing CFCs for a long time.

They were phased out of aerosol production in 1999 in favor of less harmful hydrocarbon alternatives.

However, since CFC molecules have a lifetime of 20 to 100 years in the stratosphere, the damage done in previous decades continues to make an impact.

Rogue CFCs

As refrigerants and aerosol cans containing CFCs become older and more obsolete, people tend to forget about them, leaving them to leak and further contaminate the atmosphere.

Researchers at the University of East Anglia are working on methods to pinpoint local sources of CFC exposure, such as old CFC refrigerators.

They collect air from the stratosphere and use mass spectrometers to determine the chemical makeup of CFC contamination.

Tommy Doc is a 2007 graduate of the University of Pennsylvania and an aspiring Internet entrepreneur. He was the sports editor for "The Pennsylvania Independent" while attaining his bachelor's degree in communications and environmental science. Doc is from Atlantic City, N.J. but has lived in Philadelphia, San Diego, New York and currently resides in Austin, Texas.

https://sciencing.com/sources-cfcs-8405334.html

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FLIGHT ATTENDANTS AND CANCER - Women and men on U.S. cabin crews have higher rates of many types of cancer, compared with the general population. This includes cancers of the breast, cervix, skin, thyroid and uterus, as well as gastrointestinal system cancers, which include colon, stomach, esophageal, liver and pancreatic cancers. One possible explanation for these increased rates is that flight attendants are exposed to a lot of known and potential carcinogens, or cancer-causing agents, within their work environment. One of those carcinogens is cosmic ionizing radiation, which is elevated at higher altitudes.

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Flight Attendants And Cancer

Why Cancer Rates Are Higher in Flight Attendants

By Cari Nierenberg 

This type of radiation is particularly damaging to DNA and is a known cause of breast cancer and nonmelanoma skin cancer, she said.

Air cabin crews receive the highest yearly dose of ionizing radiation on the job of all U.S. workers, she added.

In the new study, the researchers looked at data from more than 5,300 flight attendants from different airlines who completed an online survey as part of the Harvard Flight Attendant Health Study.

The analysis looked at the cancer rates in these flight attendants compared to a group of about 2,700 people who had a similar income and educational status but were not flight attendants.

The researchers found that in female flight attendants, the rates of breast cancer were about 50 percent higher than in women from the general population.

In addition, melanoma rates were more than two times higher and nonmelanoma skin cancer rates were about four times higher in female flight attendants compared with women from the general population. (Nonmelanoma skin cancers include basal cell and squamous cell carcinomas.)

These elevated cancer rates were observed despite indications of good-health behaviors, such as low levels of smoking and obesity, in the flight-attendant group as a whole, the study authors said.

Cancer rates in male flight attendants were nearly 50 percent higher for melanoma and about 10 percent higher for nonmelanoma skin cancers compared with men from the general population group, according to the findings.

Risks of very frequent flying

The potential cancer risks for flight attendants are not limited to cosmic ionizing radiation.

Cabin crew members are also regularly exposed to more UV radiation than the general population, which can make these workers more vulnerable to skin cancers, Mordukhovich said.

In addition, some studies have found that circadian rhythm disruptions, such as jet lag, might be linked with an increased risk of cancer, she said.

These disruptions could lead to changes in immune function and cell metabolism, which can reduce the suppression of tumors.

Another possible threat to the health of cabin crew members is chemical exposure, according to the study.

The women and men who worked as flight attendants prior to 1988, when smoking was first banned on some U.S. flights, were routinely exposed to secondhand smoke while on board the aircraft. 

Other chemical contaminants found in the cabin may include engine leakages, pesticides and flame retardants, which contain compounds that may act as hormone disruptors and increase the risk of some cancers, Mordukhovich said.

Further complicating matters is that flight attendants in the U.S. don't have the same occupational protections as their counterparts in the European Union.

There, exposure levels to radiation as well as work schedules are routinely monitored and adjusted to make sure flight attendants don't exceed certain guidelines for carcinogen exposure, Mordukhovich said.

There has been only limited research on the health of flight attendants, but they may not be the only air travelers to experience higher rates of cancer.

The rates may also be higher for pilots and people who fly often as passengers, Mordukhovich said.

Studies of pilots have generally shown higher rates of skin and prostate cancers, she noted, adding that pilots also have been found to have circadian rhythm disruption, but these workers have somewhat more built-in protections around their scheduling and rest times than flight attendants do.

Although the cancer risks for frequent flyers have not yet been studied, there is no reason to suspect these people would not have similar risks as those faced by cabin crews, Mordukhovich said.

Some limitations of the study are that researchers were not able to take into consideration individual UV exposures, such as sunbathing habits or leisure-time activities, which could influence skin cancer risk.

In addition, cancer rates were self-reported by study participants, and these diagnoses were not confirmed by a check of their medical records by the researchers, according to the study.

Cari Nierenberg, Live Science Contributor

https://www.livescience.com/62913-cancer-risk-flight-attendants.html

ULTRAVIOLET LIGHT - Ultraviolet radiation is electromagnetic radiation or light having a wavelength greater than 100 nm but less than 400 nm. It is also known as UV radiation, ultraviolet light, or simply UV. About 10 percent of the light output of the Sun is UV radiation. When sunlight enters the Earth's atmosphere, the light is about 50% infrared radiation, 40% visible light, and 10% ultraviolet radiation. However, the atmosphere blocks about 77% of solar UV light, mostly in shorter wavelengths. Light reaching the Earth's surface is about 53% infrared, 44% visible, and 3% UV. Ultraviolet light is produced by black lights, mercury-vapor lamps, and tanning lamps. Any sufficiently hot body emits ultraviolet light (black-body radiation). Thus, stars hotter than the Sun emit more UV light.

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Ultraviolet Light

Ultraviolet Radiation Definition

Chemistry Glossary Definition of Ultraviolet Radiation

by Anne Marie Helmenstine, Ph.D.

Ultraviolet radiation is another name for ultraviolet light. It is a part of the spectrum outside the visible range, just beyond the visible violet portion.

Ultraviolet Radiation Definition

Ultraviolet radiation is electromagnetic radiation or light having a wavelength greater than 100 nm but less than 400 nm.

It is also known as UV radiation, ultraviolet light, or simply UV.

Ultraviolet radiation has a wavelength longer than that of x-rays but shorter than that of visible light.

Although ultraviolet light is energetic enough to break some chemical bonds, it is not (usually) considered a form of ionizing radiation.

The energy absorbed by molecules can provide the activation energy to start chemical reactions and may cause some materials to flouresce or phosphoresce.

The word "ultraviolet" means "beyond violet". Ultraviolet radiation was discovered by the German physicist Johann Wilhelm Ritter in 1801.

Ritter noticed invisible light beyond the violet portion of the visible spectrum darkened silver chloride treated paper more quickly than violet light.

He called the invisible light "oxidizing rays," referring to the chemical activity of the radiation.

Most people used the phrase "chemical rays" until the end of the 19th century, when "heat rays" became known as infrared radiation and "chemical rays" became ultraviolet radiation.

Sources of Ultraviolet Radiation

About 10 percent of the light output of the Sun is UV radiation.

When sunlight enters the Earth's atmosphere, the light is about 50% infrared radiation, 40% visible light, and 10% ultraviolet radiation. However, the atmosphere blocks about 77% of solar UV light, mostly in shorter wavelengths. Light reaching the Earth's surface is about 53% infrared, 44% visible, and 3% UV.

Ultraviolet light is produced by black lights, mercury-vapor lamps, and tanning lamps.

Any sufficiently hot body emits ultraviolet light (black-body radiation). Thus, stars hotter than the Sun emit more UV light.

Categories of Ultraviolet Light

Ultraviolet light is broken into several ranges, as described by ISO standard ISO-21348:

Name	Abbreviation	Wavelength (nm)	Photon Energy (eV)	Other Names
Ultraviolet A	UVA	315-400	3.10–3.94	long-wave, black light (not absorbed by ozone)
Ultraviolet B	UVB	280-315	3.94–4.43	medium-wave (mostly absorbed by ozone)
Ultraviolet C	UVC	100-280	4.43–12.4	short-wave (completely absorbed by ozone)
Near ultraviolet	NUV	300-400	3.10–4.13	visible to fish, insects, birds, some mammals
Middle ultraviolet	MUV	200-300	4.13–6.20
Far ultraviolet	FUV	122-200	6.20–12.4
Hydrogen Lyman-alpha	H Lyman-α	121-122	10.16–10.25	spectral line of hydrogen at 121.6 nm; ionizing at shorter wavelengths
Vacuum ultraviolet	VUV	10-200	6.20–124	absorbed by oxygen, yet 150-200 nm can travel through nitrogen
Extreme ultraviolet	EUV	10-121	10.25–124	actually is ionizing radiation, although absorbed by the atmosphere

Seeing UV Light

Most people cannot see ultraviolet light, however, this is not necessarily because the human retina can't detect it.

The lens of the eye filters UVB and higher frequencies, plus most people lack the color receptor to see the light.

Children and young adults are more likely to perceive UV than older adults, but people missing a lens (aphakia) or who have had a lens replaced (as for cataract surgery) may see some UV wavelengths.

People who can see UV report it as a blue-white or violet-white color.

Insects, birds, and some mammals see near-UV light. Birds have true UV vision, as they have a fourth color receptor to perceive it.

Reindeer are an example of a mammal that sees UV light. They use it to see polar bears against snow. Other mammals use ultraviolet to see urine trails to track prey.

Anne Marie Helmenstine, Ph.D.

·   Ph.D. in biomedical sciences from the University of Tennessee at Knoxville - Oak Ridge National Laboratory.

·   Science educator with experience teaching chemistry, biology, astronomy, and physics at the high school, college, and graduate levels.

·   ThoughtCo and About Education chemistry expert since 2001.

·   Widely-published graphic artist, responsible for printable periodic tables and other illustrations used in science.

Experience

Anne Helmenstine, Ph.D. has covered chemistry for ThoughtCo and About Education since 2001, and other sciences since 2013. She taught chemistry, biology, astronomy, and physics at the high school, college, and graduate levels. She has worked as a research scientist and also abstracting and indexing diverse scientific literature for the Department of Energy.

In addition to her work as a science writer, Dr. Helmenstine currently serves as a scientific consultant, specializing in problems requiring an interdisciplinary approach. Previously, she worked as a research scientist and college professor. 

Education

Dr. Helmenstine holds a Ph.D. in biomedical sciences from the University of Tennessee at Knoxville and a B.A. in physics and mathematics with a minor in chemistry from Hastings College. In her doctoral work, Dr. Helmenstine developed ultra-sensitive chemical detection and medical diagnostic tests.

Anne Marie Helmenstine, Ph.D.

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https://www.thoughtco.com/definition-of-ultraviolet-radiation-604675