March 13, 2014

Four new chemicals that are almost certainly human made are threatening the recovery of the protective ozone layer in Earth’s upper atmosphere, according to scientists from the University of East Anglia in the United Kingdom. The origin of the gases, which were not in the atmosphere before the 1960′s, is unclear, but they appear to be coming from somewhere in the Northern Hemisphere. Even more worrisome, emissions of two of the gases seem to have risen in recent years.

Ozone is a gas that is present in small amounts in Earth’s atmosphere. In the troposphere (the lowest level of the atmosphere), ozone is a pollutant. However, in the stratosphere (the layer above the troposphere), ozone blocks harmful ultraviolet rays from the sun, protecting life on Earth.

In the 1970′s, scientists monitoring the atmosphere over Antarctica noticed that the ozone layer was becoming depleted (less concentrated) each spring. This area became known as the ozone hole. In 1985, researchers discovered that the ozone hole had grown since the 1960′s. That is, over the years, the area of low concentrations of ozone had become larger. In addition, the ozone concentrations had become smaller. Scientists soon linked the ozone hole to chemicals called chlorofluorocarbons (CFC’s). CFV’s were once widely used as refrigerants and as propellants in aerosol spray cans. The international community acted quickly to protect the ozone layer. In 2010, a total global ban on CFC production went into effect. But an ozone hole still occurs every year because of CFC molecules that remain in the atmosphere. Although atmospheric concentrations of ozone-damaging chemicals have fallen in recent years, the ozone hole was not expected to heal completely until at least 2050.

A false-color view shows the total ozone over the Antarctic pole on March 7, 2014. The purple and blue colors are where there is the least ozone, and the yellows and reds show where there is more ozone. (NASA/Goodard Flight Center)

Three of the newly discovered chemicals in the ozone layer are CFC’s. The fourth is a hydrochlorofluorocarbon (HCFC), which also damages atmospheric ozone. The British scientists reported that 82,000 short tons (74,000 tonnes) of the gases have been released into the atmosphere so far. Analyses of old, compact snow, known as firn, and modern air samples revealed that the gases have appeared in the past 40 to 50 years.

The scientists speculated that the new chemicals could be appearing because of loopholes in the Montreal Protocol, which banned most CFC’s. The treaty allows the use of extremely small amounts of CFC’s in the manufacture of certain insecticides and in solvents used to clean electronic equipment. However, the gas emissions could also be the result of illegal production. The scientists called on governments to identify the source of the gases so production can be halted immediately.

Additional World Book articles:

• Air pollution
• Greenhouse effect
• Rowland, Frank Sherwood
• Smog
• Environmental pollution (1988) (a Back in Time article)
• Environmental pollution (1990) (a Back in Time article)

March 12, 2013

Infections caused by a particularly frightening form of drug-resistant germ are on the rise in U.S. hospitals. Health-care experts and the U.S. Centers for Disease Control and Prevention (CDC) are warning in particular about the rise of a new form of bacteria, a drug-resistant enterobacteria. Enterobacteria are normal in the digestive system of humans, but they can cause infections and illness when they invade such other areas of the body as the blood stream or bladder. Infections caused by normal enterobacteria can be treated with antibiotics and cured. The new form of enterobacteria is resistant to all antibiotics, even drugs used by doctors as a last resort, such as carbapenems. Because of this resistance, the form is called carbapenem-resistant enterobacteria, or CRE’s.

Bacteria, such as this Clostridium, can cause serious infections in humans. (© David Phillips, Visuals Unlimited/Getty Images)

The fatality rate for people who contract this virtually untreatable type of infection in the bloodstream is around 50 percent. In addition, CRE’s have the ability to share their drug resistance–their genetic defenses against antibiotics–with other bacteria.

For now, CRE’s are found only in hospitals in the United States. Experts fear is that as it becomes more common in hospitals, it will eventually enter the community and begin infecting large populations.

It is possible for hospitals to reduce patients’ incidence of, and thereby infection with, drug-resistant bacteria. Some methods include 1) quickly identifying and  isolating patients who test positive for such bacteria; 2) monitoring closely and lowering usage of antibiotics in hospital settings, as many drug-resistant germs thrive in settings where antibiotics are widely used;  3) more careful cleaning of patient rooms; and 4) vigilant hand washing on the part of all staff and visitors.

One aid in fighting this infection could be on the horizon. An American epidemiologist, Mark Stibich, has invented a robot that disinfects hospital rooms using pulses of ultraviolet (UV) light. The light used can disinfect both hard and soft surfaces. Thus far, only about 100 hospitals worldwide use the robot, but studies at such hospitals report a 75-percent drop in the rate of infection with another supergerm, Clostridium difficile (or C. diff).  UV light works by disrupting the DNA of an organism, so it kills bacteria, even bacteria that have drug resistance.

Additional World Book articles:

• Antibiotic resistance
• Bacteria

Another website of interest:

• Centers for Disease Control and Prevention