Dear Doctors: I just saw on the news that the smoke from wildfires is even worse for your health than we thought. Why is that? It seems like the smoke spreads for miles, so I’m worried. Is there anything we can do?

Dear Reader: Unfortunately, you are correct about all of this. Wildfires have not only become more frequent, they are burning hotter and longer. The National Interagency Fire Center reports that more than 61,000 wildfires burned close to 9 million acres across the United States last year. And while the fires themselves are local, the smoke they emit is not. As so many of us have experienced, wildfire smoke travels great distances. It can affect people living hundreds of miles, and sometimes even thousands of miles, away from the blaze.

The news reports you saw appear to be prompted by several new studies. One found wildfire smoke now accounts for one-fourth of the dangerous air pollution in the U.S. Other new research suggests that as fires burn, microbes in the fuel and soil are lofted into the air and carried far from their original locations. In the West, this includes a genus of fungi known as Coccidioides, which causes valley fever, a serious respiratory illness. Many wildfires now spread to urban areas. This adds plastics, polymers, chemicals and the host of other materials in our built environment to the toxic mix.

One of the things that makes wildfire smoke so dangerous is the high levels of fine particulates it contains. The most dangerous of these are known as PM2.5. The letters stand for the words “particulate matter,” and 2.5 refers to their microscopic size of less than 2.5 microns. When you breathe in air that contains wildfire smoke, these minute particulates enter the airways. They travel deep into the lungs, where they lodge in and inflame the delicate tissues. PM2.5 are so small, they can also pass into the blood stream and travel throughout the body.

All of this makes it crucial to take the health threats of wildfire smoke seriously. It is particularly true for people living with asthma, allergies and chronic obstructive pulmonary disease (COPD), and people with chronic heart disease. Exposure to wildfire smoke can cause throat irritation, watery or itchy eyes, sneezing, coughing, wheezing, a runny nose, congestion, rapid heartbeat, chest discomfort, shortness of breath and exhaustion.

Protect yourself by tracking air quality in your area. Whenever it drops to unhealthful levels, take steps to minimize exposure. If possible, stay indoors. Keep windows and doors tightly closed. If your home has central air conditioning or a HEPA filter, use it. But don’t run window AC units, as they draw unfiltered exterior air into the home. Protect indoor air quality. Don’t burn candles, use aerosol sprays or stir up indoor particulates by vacuuming or dusting. Avoid any unnecessary exertion.

Anyone who uses a rescue inhaler should have one ready. Check regularly to see if anyone is experiencing adverse symptoms, and be willing to seek medical help if needed. If you do have be outside, wear an N95 or better mask, even when you can’t smell or see the smoke.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: Ever since I was little, I have absolutely hated the sound of other people chewing. Whenever I try to explain this to someone, they think I’m overreacting or even making it up. Is this something you have come across before? Does anyone know why it happens?

Dear Reader: You are describing a condition known as misophonia. The term comes from the Greek word “misos,” which means dislike or hatred, and “phonia,” which derives from the Greek word for speech or sound. The condition is marked by a powerful aversion to certain commonplace sounds. These can include mouth sounds such as chewing, swallowing, yawning, burping, breathing or throat clearing, and repetitive sounds, such as finger tapping, typing or the clicking of a pen. Hearing the specific sound triggers feelings of anxiety, disgust, anger and, in some cases, even rage.

For people who don’t experience misophonia, these sounds don’t even register, let alone provoke a reaction. As a result, as you have repeatedly experienced, trying to explain the condition can be frustrating.

Although it may not be widely known, misophonia is actually somewhat common. It is estimated that between 10% and 20% of people experience it. It appears more often in women, with between 15% and 25% being affected. It is also more likely to occur in people living with autism spectrum disorders, obsessive-compulsive disorder and those affected by post-traumatic stress. Genetics are also believed to play a role. The condition can develop at any age, but often emerges in early adolescence. Some people have just a single sound that incites a response, while others can have multiple triggers.

The cause of misophonia is not yet understood. Recent research points to possible structural anomalies in an area of the brain known as the anterior insular cortex. This is a type of processing center, located deep in the brain, that receives sensory input from multiple areas of the body. Among its many and complex roles is contributing to emotional response and aiding in the integration of sound. Brain scans have shown that when people with misophonia are exposed to their trigger sounds, activity in the anterior insular cortex spikes, and is significantly higher than in people without the condition.

There is no cure for the condition at this time. Instead, the focus is on management. Many people find that adding music, a sound machine or background TV to group mealtimes can successfully mask the mouth sounds that act as triggers. When out in public, using ear plugs, ear buds or sound-canceling headphones can be helpful. Various forms of psychotherapy, such as cognitive behavioral, group and talk therapy, can help ease the emotional stresses of the condition. Some people derive benefit from the use of certain medications, including beta blockers. These blunt the fight-or-flight symptoms of anxiety, sweating, muscle tension and increased heartbeat that often accompany misophonia.

Because the effects of misophonia are so unusual, it is possible to have the condition and not realize it. If anyone finds that the symptoms or circumstances we have discussed relate to them, don’t hesitate to bring them up with your health care provider.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: Our 11-year-old son is fascinated with those astronauts who are stuck on the space station. One of the things he asks about a lot is how being in space for that long affects the human body. Do you know what the latest research says about that?

Dear Reader: You are referring to two American astronauts who arrived at the International Space Station last June for what was planned to be an eight-day mission. When the experimental spacecraft they had piloted developed technical difficulties, however, NASA decided the pair should wait for the arrival of a replacement spacecraft to make the return trip. As of New Year’s Day, the two astronauts had logged more than 200 days in space. They are not scheduled to return to Earth until at least March.

As the astronauts await their ride home, they are undergoing significant physiological changes. That’s because our bodies have evolved to both overcome and to utilize the pull of gravity. The absence of that constant resistance affects every cell, tissue, structure and biological system. That’s why astronauts in space spend hours each day exercising.

Without the pull of gravity to work against, muscle mass decreases and muscles begin to atrophy. Within several weeks, astronauts lose up to 10% to 20% of their lean muscle mass. Weightlessness erases the physical cues that trigger bone remodeling. This is the process in which new bone continuously replaces old bone. As a result, bone mass in astronauts decreases by 1% to 2% every month they spend in space.

Fluids change their behavior in the microgravity of space, as well. This adversely affects the heart, circulation and blood pressure; leads to persistent nasal congestion; causes tissues of the face and upper body to become swollen; affects the inner ear and vision; and even results in increased flatulence and constipation.

The vacuum of space also interferes with the production of red blood cells, resulting in a condition dubbed “space anemia.” Astronauts are exposed to higher amounts of ionizing radiation, which can increase cancer risk. There is also emerging evidence that space travel affects the structure of the human brain.

The newest research has found that living in space even causes changes to human DNA. This was discovered in a fascinating study of identical twin brothers Scott and Mark Kelly. Both are astronauts who have spent time in space. From March 2015 to March 2016, while Mark remained on Earth, Scott lived on the International Space Station. Upon Scott’s return after a year spent living in zero gravity, genetic analysis found that almost 1,000 of his chromosomes and genes worked differently than those of his twin brother.

The good news is many of the adverse effects of space travel resolve upon return to Earth. Some, such as the effects of fluid shifts, take only a short time. Others, including loss of muscle mass, bone density and cognitive effects, can take many months and intense rehabilitation to overcome. Some can be permanent. That has made the development of space suits and space craft to mitigate these effects a priority within the global space community.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)