Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

Current Carbon Monoxide Standards Protect Health: EPA

Current U.S. national air quality standards for carbon monoxide (CO) protect public health and the environment, according to the Environmental Protection Agency.

The agency also said that levels of CO in the air have fallen by 80 percent since 1980, mostly due to motor vehicle emissions controls.

The current health standards are 9 parts per million (ppm) measured over 8 hours, and 35 ppm measured over 1 hour. CO levels at monitors across the country are well below the standards.

CO is a colorless, odorless gas that can harm health by reducing oxygen delivery to the body's tissues and organs, including the heart and brain, the EPA said.

Revised air monitoring requirements to be implemented in the next few years will require CO monitors to be placed near roads in 52 urban areas with populations of 1 million or more. This will provide the EPA with data about CO levels that may be affecting the health of people who live in neighborhoods near busy roads.

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Not All Obese People Unhealthy: Studies

Some obese people may be healthy and don't need to lose weight, two new studies suggest.

They challenge the common belief that body mass index (BMI) and weight determine health, CNN reported. One group of researchers estimated that one in five obese people may not have medical issues.

But it can be difficult to distinguish between the "healthy obese" and obese people who currently don't have weight-related health issues but may develop them in the future.

"Our study challenges the idea that all obese individuals need to lose weight," said Dr. Jennifer Kuk, assistant professor, School of Kinesiology & Health Sciences at York University in Toronto, CNN reported.

The studies were published in the Canadian Medical Association Journal and Applied Physiology, Nutrition and Metabolism.

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Ground Beef Recalled

About 60,000 pounds of ground beef sold mainly in the southeastern United States have been recalled because it could be tainted with E. coli bacteria.

The recall of the meat from National Beef Packaging Co. of Dodge City, Kan. was announced after the Ohio Department of Agriculture detected the bacteria during routine testing, the Associated Press reported.

At least three major grocery store chains -- Winn-Dixie Stores Inc, Publix Super Markets Inc., and Kroger Co. -- have recalled packages of the ground beef sold mainly in Alabama, Florida, Georgia, Louisiana, Mississippi, South Carolina and Tennessee.

The companies advised consumers to return the ground beef to their stores for a full refund, the AP reported.

There have been no reports of illnesses, according to the U.S. Department of Agriculture.

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Bat on Flight Causes Rabies Concerns

U.S. health officials are concerned about possible rabies exposure among 50 airline passengers who may have had contact with a bat that was on an Aug. 5 Delta flight from Madison, Wis. to Atlanta.

The airliner returned to Madison after the bat appeared, but it's not known if the bat had rabies because it escaped after the plane landed, the Associated Press reported.

The Centers for Disease Control and Prevention is trying to reach all the passengers who were on the 6:45 a.m. flight 5121 in order to make sure they didn't have close contact with the bat.

As of last Friday, the CDC had talked to only 13 of the passengers and is asking the other passengers to call 1-866-613-2683, the AP reported.

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Excess Fat Affects Body's Sugar Sensors: Study

A high-fat diet can trigger type 2 diabetes by interfering with the body's sugar sensors, according to a new study.

Being overweight is one of the main risk factors for type 2 diabetes. Learning more about the link between fat and type 2 diabetes could help lead to a cure, according to the researchers at the University of California and the Sanford-Burnham Medical Research Institute, BBC News reported.

The study, conducted with mice and human pancreatic cells, appears in the journal Nature Medicine.

The findings are interesting and this is a "theory worth investigating further," Dr. Iain Frame, director of research at Diabetes UK, told BBC News.