**Aaron Goodman:** Welcome to *The Chemical Sensitivity Podcast*. I'm Aaron Goodman. For many people with multiple chemical sensitivity, or MCS, getting a diagnosis and appropriate care remains out of reach. What could change if healthcare providers recognized the illness sooner and took people's symptoms seriously?

My guest today is Dr. Pilar Muñoz-Calero, a leading expert on MCS in Spain. She is a physician whose own experience with illness led her to focus on environmental medicine through the Alborada Foundation. "Cuanto antes seamos capaces de diagnosticar una persona con sensibilidad química, van a—" "The earlier we can diagnose someone with multiple chemical sensitivity, the much greater improvement they can achieve compared with those who already have very severe chemical sensitivities." "Muy, muy severas."

Dr. Pilar Muñoz-Calero's words highlight the need for accessible, informed healthcare and the consequences when people are left without recognition or support. I hiked for an hour to reach her home outside Madrid because I felt it was important to share her insights with a global audience of people with lived experience of MCS, as well as clinicians and researchers and the broader public.

This conversation is part of a series with people across Europe, including clinicians, researchers, lawyers, advocates, and people living with MCS. By bringing together their perspectives, I hope to help people working on MCS connect across countries. Pilar and I discuss the barriers to diagnosis and care, her perspectives on reducing exposures, and what she has learned from listening to people with the illness.

Please check out and share the podcast website, listen.chemicalsensitivitypodcast.org. It's an easy way to introduce friends, family members, healthcare providers, researchers, and others to conversations about MCS. And please subscribe wherever you get your podcasts. Follow *The Chemical Sensitivity Podcast* on YouTube, Facebook, X, Instagram, BlueSky, and TikTok. You can reach me at aaron@chemicalsensitivitypodcast.org. Here's my conversation with Dr. Pilar Muñoz-Calero. This is the English-dubbed version. The original Spanish-language conversation is also available on the podcast. Thanks for listening.

**Aaron Goodman:** Could you please introduce yourself and tell us about your work in environmental medicine at the Alborada Foundation and how your interest in multiple chemical sensitivity began?

**Dr. Pilar Muñoz-Calero:** Initially, the Alborada Foundation, established in 1998, had a very different purpose, primarily helping rehabilitate people with addiction problems. Shortly afterward, I developed multiple chemical sensitivity. I became very ill, and that sparked my interest in studying MCS more deeply. I had to go to the United States.

I was treated there and recovered there. When I returned to Spain, I changed the foundation's mission and began working in environmental medicine. So my interest rose primarily because of my own illness. Developing it led me to explore it much more deeply. My experience with multiple chemical sensitivity was truly, if I can find an appropriate word, dramatic.

About twenty-five years ago, I began experiencing a series of symptoms that I could not clearly identify. Even though I was a physician and spoke with many of my colleagues, we did not know what was causing them. Eventually, I was not able to live anywhere except in nature. I ended up in a wheelchair, lost my memory, and was unable to carry out a conversation.

I had pain throughout my body, cognitive problems, respiratory problems, and more. An endless list of symptoms made my life absolutely dramatic and terrible. All of this caused me to stop eating. I lost the ability to nourish myself. I had complete food intolerance. I even went three months without being able to eat anything at all.

Eventually, I had to go to the United States to an environmental control unit in Dallas. Professor William Rea diagnosed me with multiple chemical sensitivity because here they did not know what was happening to me. When I arrived, he told me that I had practically arrived too late, that my poisoning, particularly from heavy metals and especially mercury, could be described as incompatible with life.

So we began a seven-month struggle between life and death, and I was able to recover after those seven months. Afterward, I came back to Spain and continued recovering very slowly, but we're talking about years. I was then able to carry out all the treatments I had learned about in the United States through the first clinic I opened with the Alborada Foundation.

**Aaron Goodman:** How has your own personal experience with multiple chemical sensitivity influenced your work as a clinician specializing in this condition?

**Dr. Pilar Muñoz-Calero:** The multiple chemical sensitivity I live with, although I'm doing very well now, has influenced everything. Before I developed this sensitivity, this hypersensitivity, I knew absolutely nothing about any of this as a physician. I had no idea, and neither, of course, did any of my fellow physicians or healthcare professionals.

When I was in the United States undergoing treatment, every Tuesday, the leading experts of the United States would come to the Dallas clinic and meet to discuss clinical cases. They invited me because I was a physician. I remember going in my wheelchair. I was unable to walk at that time, and there were things I could barely even remember.

But over those seven months, I gradually recovered and went every Tuesday to listen. That was where my enthusiasm and my true calling in medicine began again when I rediscovered medicine through environmental medicine.

**Aaron Goodman:** What is the current situation for people with MCS in Spain? Approximately how many people might be affected, and how much recognition does the illness have? And how easy is it to obtain a diagnosis and appropriate medical care?

**Dr. Pilar Muñoz-Calero:** Those are very interesting questions. This illness, multiple chemical sensitivity, is really marked by the struggle for rights and by different scientific advances. We can talk about the Madrid Declaration in April 2026. Patient organizations such as the Afibron Association have launched an international campaign demanding that multiple chemical sensitivity be included with its own specific, distinct diagnostic code in the International Classification of Diseases, ICD-11.

We can also talk about legal recognition. In Spain, multiple chemical sensitivity remains coded under code 78.40 in ICD-10. The National Coalition, CONFESC, has also submitted an urgent sociological report denouncing the lack of workplace accommodations and accessibility in various public spaces for people affected in the country.

More epidemiological studies are also progressing, although very slowly. In Spain, it is estimated that there are approximately between one hundred thousand and four hundred thousand people affected, but we really should not place too much weight on that figure because the condition is greatly underdiagnosed precisely because of the lack of knowledge, awareness, and information among physicians in general, especially in primary care.

Of course, many people therefore remain undiagnosed. There's no official registry precisely because of all of these problems. We hope to continue making progress. Most of those affected in Spain are women between roughly thirty-five and sixty years of age.

Recognition, diagnosis, and access to appropriate medical care for multiple chemical sensitivity in Spain, another of the questions you asked, show a significant disconnect between the legal or theoretical framework and the actual healthcare experience of patients. In terms of official and legal recognition, there is a national code, as I have already said, in ICD-10.

Our international challenge is to have it included in the World Health Organization's ICD-11. We have therefore submitted a series of documents demanding that the World Health Organization recognize it. It is also important to consider work disability. Supreme Court case law has already upheld permanent disability for many affected people on multiple occasions.

As a physician and an official expert witness, I often attend these court proceedings, and there does seem to be increasing progress on the legal side. In terms of medical diagnosis, in Spain it is strictly clinical because there is no pathognomonic biomarker that can establish a cause-and-effect relationship.

That, of course, makes recognition more difficult. As for access to appropriate medical care, there is a lack of specialized units. There is no national network of environmental medicine units in the public healthcare system. There's also a barrier to hospital accessibility. What do I mean? There's an obstacle because the protocols for what we call clean spaces or protective bubbles allowing these people to attend hospitals are not in place.

So although various protocols for hospital access are being developed, there's still a very long way to go. As I mentioned earlier, Spain has officially recognized multiple chemical sensitivity since twenty fourteen. Nevertheless, there is still a lack of medical credibility. As I also said before, there are no clear biomarkers or universal laboratory tests for diagnosis.

Many medical professionals therefore still consider MCS to be a purely somatoform or psychological disorder. It's common for family doctors to suspect the condition now because they have heard of it. But specialist departments such as internal medicine or allergy services reject referrals, arguing that they do not recognize MCS as a valid clinical entity.

There is also resistance to accommodations. It would be important to take simple measures such as ventilating spaces, removing air fresheners, restricting perfumes, and so on. Then there's litigation over disability. Because of this distrust on the part of the National Social Security Institute, the INS as it is called here in Spain, obtaining medical leave or permanent disability status often requires long and expensive court proceedings.

Naturally, this causes enormous suffering for patients, not only because they feel unwell, but also because of this lack of understanding. Perceptions in Spanish society perpetuate stigma because of the complete lack of understanding of the mechanisms of the illness. There is invisibility and isolation.

The label of exaggeration is so common. They're exaggerating. These are patients who exaggerate. That's truly terrible. Then there is gender bias. Since the overwhelming majority of people diagnosed in Spain are women, multiple chemical sensitivity carries a historic gender bias and is more likely to be dismissed as women with anxiety or a somewhat histrionic personality. Unfortunately, that is still the situation we are in.

**Aaron Goodman:** For listeners who may not be familiar with multiple chemical sensitivity, how do you define and understand this illness as a physician?

**Dr. Pilar Muñoz-Calero:** Multiple chemical sensitivity is an acquired chronic syndrome that causes many physical symptoms, some of them very severe, in response to exposure to minimal levels of everyday chemicals that other people tolerate, in quotation marks, well. I say in quotation marks because the absence of an immediate reaction when people are exposed to these pollutants does not mean they stop being pollutants.

They are still toxic. Therefore, even if these people do not develop chemical sensitivity, over time they may develop autoimmune diseases, inflammatory, degenerative, or chronic illnesses, various kinds of hypersensitivity, and even cancer. In terms of current medical understanding, first we know, as I have mentioned several times, that there is recognition in Spain because it is included in the International Classification of Diseases ICD-10.

There is also increasing medical awareness of a biological mechanism, although that knowledge is not yet widespread among healthcare professionals.

One of the most widely accepted hypotheses concerns central sensitization, a dysfunction of the central nervous system that amplifies responses to chemical stimuli. We also have to consider the physical nature of the illness. Evidence-based medicine rules out its being a phobia or a psychological disorder.

More and more studies confirm that it is an organic physical condition. When I first became involved in all of this, practically everyone thought it was a psychological illness. All patients were referred directly to a psychologist or psychiatrist. But thanks to a great deal of research that has increasingly been conducted, hypotheses suggesting that these are psychological illnesses are becoming weaker and weaker.

Another problem, as I have mentioned, is the lack of biomarkers. Since there are no blood tests or imaging tests that directly diagnose, it is identified mainly through clinical criteria. Because physicians generally do not know those criteria, I repeat that these conditions are greatly under-diagnosed.

**Aaron Goodman:** Are there possible subtypes of MCS and different biological pathways or mechanisms?

**Dr. Pilar Muñoz-Calero:** This is important because multiple chemical sensitivity is a complex multi-system illness, and current medicine proposes that there is no single origin, rather different clinical profiles and subtypes coexist.

Let's look at the subtypes we're talking about. First, there is an acute onset subtype, people who experience an exposure and suddenly develop the syndrome after a single event involving massive acute exposure, for example, to a particular chemical. This often happens with occupational exposures, but it has also occurred throughout history.

We can recall events such as Bhopal, India, when there was a gas leak at the American company Union Carbide. An accident occurred at midnight and a gas was released. It was a huge problem because there were, I believe, more than 30,000 deaths. The number is not entirely clear, but it has been said that there may even be as many as 30,000 deaths.

I went there 40 years later and experienced how the water was still contaminated. Many people developed multiple chemical sensitivity in those circumstances, and it is an example of what we are discussing, the acute onset subtype. Most people, however, tend to fall into the subtype involving progressive accumulation.

It is chronic and insidious. There is gradual daily accumulation that we do not notice. We adapt and a masking effect develops. We do not notice until the moment when the final straw comes. The body's homeostatus breaks down and the illness appears.

As for the main hypotheses and biological mechanisms, there is central sensitization, this hypersensitivity of the nervous system. Another very important increasingly studied mechanism involves oxidative stress and the nitric oxide cycle, extensively studied by biochemistry professor Martin Pall at Washington State University.

We also discuss the possibility of changes in metabolic biotransformation, phases one and two of detoxification, which are directly impaired in some people. And we can also discuss immune and inflammatory dysfunction, which is seen in many patients.

**Aaron Goodman:** Are there possible warning signs and opportunities to recognize MCS before it becomes severe?

**Dr. Pilar Muñoz-Calero:** There are indeed a number of early warning signs in what we usually call the initial phase. These primarily include intolerance to smells. Everyday smells, perfumes, fabric softeners, gasoline, bleach, ammonia, and so on suddenly seem unbearable, persistent, or very unpleasant. Recurrent mucous membrane symptoms are also common.

We begin to experience throat irritation, nasal congestion, watery eyes, or a dry cough, often unexplained, that appear only when entering particular spaces where exposure occurs. For example, places that have just been painted, where a strong cleaning product has just been used, or around people wearing perfume or using a strong fabric softener.

Other common early signs include headaches and temporary brain fog, headaches, a feeling of mental dullness, mild dizziness, or short-lived concentration problems that resolve when the person goes outdoors. There's that feeling of being somewhat drunk without having consumed alcohol because of saturation of the metabolic pathways.

It's also common to find people who begin complaining early on of fatigue or feeling unwell after exposure, extreme tiredness or generalized weakness a few hours after exposure to a source of chemical substances. In those cases, the most important thing is immediate environmental control, trying to adapt the workplace as well and preventing the spreading effect.

In these early stages, sensitivity is usually limited to one or two substances, but if we continue exposing ourselves, we eventually become sensitized to them all.

**Aaron Goodman:** Could you talk a little bit about treatments and interventions for MCS, possibilities for improvement, and differences between patients who improve and those who remain severely affected?

**Dr. Pilar Muñoz-Calero:** At present, there is no universal pharmaceutical cure for multiple chemical sensitivity. The current medical approach focuses primarily on symptom management, systemic support, and stabilizing the patient through three main interventions.

One, of course, is environmental avoidance. Whenever patients come to see me, the first treatment step I recommend so they can begin improving is environmental control. For this, we have what we call the environmental ambulance. We work with technicians who visit the home and assess its pollutants. Not only chemical ones such as cleaning products, colognes, cosmetics, and so on, but also building materials and physical factors such as electromagnetic fields and whether there is proper electrical grounding.

Dirty electricity is also important. All of this is extremely important to assess, and by minimizing it, we begin noticing improvements. Nutritional and antioxidant support are also important for treatment. These people exhaust their resources and have many problems with nutrition. These nutrients are not only used to nourish us, they also serve as cofactors or coenzymes that enable our metabolic pathways to function properly, including pathways as important as detoxification.

If we cannot detoxify properly, our toxic load increases. Eventually, these pollutants accumulate in the body and cause these kinds of problems. We also use neuroregulation techniques and psychological and body-based support. There is an alteration of the nervous system, and psychological problems can arise as a consequence, not as a cause of the limitations these people experience.

The illness is not psychological. Rather, being unable to leave home, having to remain in a protective bubble, and not being understood lead to psychological problems that are very important to take into account.

So how can we help these people improve? Without question, through early diagnosis. The earlier we can diagnose someone with multiple chemical sensitivity, the more they will improve. Certainly much more than people who come to us with very, very severe chemical sensitivities.

Environmental control is another important factor. People who have a real ability to isolate themselves from toxic substances, patients with more resources to adapt their homes or even move, which is sometimes necessary because otherwise we will not see any improvement.

There is also the possibility of changing jobs, for example, working remotely. But people who lack this financial or family support are forced to remain in polluted urban workplaces. Naturally, it is much harder for treatment to be effective.

It is also important to consider the degree of comorbidity and genetic factors. Severely affected patients commonly have overlapping complex conditions such as fibromyalgia, chronic fatigue syndrome, and mast cell activation syndrome. There may also be severe genetic mutations, such as mutations involving cytochrome P450, GST, or the MTHFR gene.

For example, in my case, I developed not only chemical sensitivity, but also fibromyalgia, chronic fatigue syndrome, mast cell activation, Lyme disease, and problems involving mycotoxins. It was a whole complex of conditions that made my situation tremendously serious and severe. In these cases, naturally, the response is poorer and much slower, and we need far more time to improve.

**Aaron Goodman:** Could you talk about the importance of reducing exposures and the possibility of creating fragrance-free or perfume-free spaces in workplaces, hospitals, schools, public transportation, and other shared spaces?

**Dr. Pilar Muñoz-Calero:** When creating fragrance-free spaces, it's important to consider this sector by sector. For example, workplaces should implement zero fragrance policies. Just as smoking is prohibited, fragrances should be prohibited in these spaces. In fact, there are already many places around the world that describe themselves as fragrance-free. Air fresheners should be prohibited, especially plug-ins and aerosols, but really all types of air fresheners.

Cleaning products should have no smell. Natural options should be used. Many patients who come to our clinic ask us to provide a report so their workplaces stop cleaning with products that are so harsh and harmful to them.

Besides workplaces, it's very important to consider hospitals and health centers, creating separate ventilated waiting rooms for patients with MCS. They have the same right to go to a hospital, yet sometimes they cannot go precisely because no spaces are prepared for them.

Schools and educational centers are also extremely important. Conventional cleaning products should be replaced with ecological fragrance-free alternatives because children are even more vulnerable.

The number of people affected by multiple chemical sensitivity continues to grow because these exposures are increasing. Public transportation should also improve and optimize air renewal and filtration systems in train carriages and buses and completely eliminate fragrance use. When you travel, for example, on a high-speed train, they ask you not to use your mobile phone, to turn it off or to lower its volume.

We should also ask for smells to be reduced. Just as smoking is prohibited, we should try to make these places fragrance-free as well because more and more people are affected and they have the same right to use public transportation. This also applies to other shared spaces such as cinemas, hotels, and government offices.

Whenever I travel, for example, I always make a point of calling the hotel and asking them not to clean my room with any strong soap or use any air freshener. Just water and baking soda and so on. It is increasingly important to take all of this into account.

For these public spaces, I'll mention some measures that are not particularly complicated to implement, such as air purification and mechanical filtration systems with HEPA filters. It can also be useful to place containers of activated charcoal or baking soda, which absorb odors.

Then there's chemical substitution and green certification, comprehensively replacing institutional maintenance and cleaning product ranges with solutions that have low gas emissions, such as low emissions of VOCs, volatile organic compounds.

There should also be protocols for natural and forced ventilation, designing continuous air renewal systems in enclosed buildings, ensuring a clean flow of outdoor air, and eliminating stagnant recirculation of scented particles. These measures would greatly benefit all of these people.

**Aaron Goodman:** Could you talk about why some clinicians and researchers continue to treat multiple chemical sensitivity as a psychological condition? And what do researchers and healthcare providers need to understand about the biological basis of MCS and the experiences of people who are affected?

**Dr. Pilar Muñoz-Calero:** Psychological interpretations stem from a historical bias. Historically, because standard laboratory tests did not show abnormalities, as we discussed earlier, some sectors of medicine treated multiple chemical sensitivity as if it were a mental health disorder. They classified patients as having somatoform or anxiety disorders.

In fact, here in Spain, the National Social Security Institute, the INS, placed it directly under a heading for somatoform disorders in one of its guides. We organized a protest, bringing together environmental medicine experts and some associations, and ultimately they had to withdraw the guide because we demonstrated through various studies that this was not true.

Another issue was classical behavioral conditioning. Some approaches claim that patients mistakenly associated a smell or an environment with a previous traumatic experience. In other words, when they were children and experienced a trauma, there might have been a particular smell present. They identified it, linked it to the experience, and it stayed with them psychologically, causing reactions later. Yet it has been shown that this is not the case.

Then there is the nocebo effect. We should talk not only about the placebo effect, but also the nocebo effect. It has also been argued that expecting to become ill when smelling a chemical psychologically triggered real physical symptoms. In other words, that it made those symptoms real. Yet it has been shown that this is not the case. There are already many hypotheses and a great deal of very plausible research saying that this is not true.

What physicians and researchers need to understand is the biological basis. The biological basis exists and demonstrates that multiple chemical sensitivity is a multifactorial organic illness. Healthcare professionals need to update their knowledge. I tell many of my patients when they come in, "You should insist that your doctors bring themselves up to date." All of these data are already included even in the National Occupational Encyclopedia here in Spain. We should not allow physicians to fail to update their knowledge and stay current.

For example, I'm registered with a medical council in England, and there physicians are required to keep their knowledge current continuously, which does not happen here in Spain. The misinformation that leads to such a lack of knowledge results in incorrect diagnoses and increases patients' suffering.

Clearly, physicians should already know that the organic basis would involve central sensitization as we discussed earlier. There are also studies on the dysfunction of TRP receptors. Many studies examine these receptors, which are activated by pollutants and trigger pathways of neurogenic inflammation and pain, explaining many of the symptoms of these illnesses.

There's also cellular oxidative stress and all the work by Professor Martin Pall, whom I mentioned earlier, on the nitric oxide cycle. This involves the stimulation of many pro-inflammatory cytokines causing an enormous increase in the amount of calcium inside cells and damage that begins locally and eventually becomes generalized throughout the body.

Physicians should already be up to date on all of this. In fact, I teach medical students from the first through the sixth years at Complutense University, and they know nothing about it. They are not taught this, and that should already be sounding alarm bells so that it stops happening.

What's happening to patients? Understanding the biological basis is really the only way to radically transform their daily lives. Otherwise, imagine a patient who is directly told that they have a psychological problem. When a professional insists on the psychological approach, they invalidate the person's symptoms. This delays diagnosis and forces patients to remain exposed to substances that worsen their neurological damage irreversibly.

It also increases forced isolation imposed by their environment. The person experiences the involuntary loss of employment, family relationships, and social participation because the outside world is biologically hostile to their body. And whom does the family member listen to? Unfortunately, they listen to the physician, even though the physician's lack of knowledge leads them to make diagnostic mistakes.

I often devote the first consultation to the family member. I usually ask family members to attend because my initial instructions and explanations are primarily directed to them. Often, the family member is eager for me to say, "No, no, no, this is a psychological illness." They want me to prescribe medication or psychological or psychiatric therapies that will avoid the need for the whole family to make changes, which is often what they want to avoid.

All of this is causing tremendous harm and increasing these patients' suffering. It produces secondary psychological stress, which, as I said before, is not the cause, but develops as a consequence. We really have to put an end to this once and for all because the suffering being caused is truly horrible.

I also need to say that some tests already provide very clear and evident findings. For example, brain SPECT scans in patients with multiple chemical sensitivity have shown clear baseline hypoperfusion. In other words, less blood reaches specific areas of the cerebral cortex. This test is often used when we go to court to seek disability status because it's very important and clearly demonstrates organic changes rather than a psychological problem.

What's the difficulty? Not everyone with multiple chemical sensitivity has a positive brain SPECT scan. That does not mean they do not have multiple chemical sensitivity, but it is important to take it into account, particularly for people whose results are positive. There is also an exacerbated response after an exposure. A brain SPECT scan is performed, followed by an exposure, and changes or abnormalities in the images can clearly be seen afterward. That has great medical and legal significance.

**Aaron Goodman:** I'd like to ask you about any observations you've had about clinical patterns that you've identified in your medical practice that have not yet been sufficiently studied or reflected in the scientific literature about MCS.

**Dr. Pilar Muñoz-Calero:** Specialist physicians who care for patients with MCS repeatedly observe certain phenomena, comorbidities, and treatment responses that mainstream science has not yet validated through large-scale clinical trials. What am I talking about? Which observed clinical patterns do I mean? Extreme hormonal fluctuations frequently appear.

Women with multiple chemical sensitivity are observed to experience drastic worsening of their sensitivity, for example, during the premenstrual period, pregnancy, or menopause. This suggests a strong interaction between estrogen levels and hyper excitability of neuronal receptors such as TRP, as we discussed earlier, and a metabolic connection that is barely outlined in current textbooks.

We can also talk about non-chemical cross-intolerances. Many professionals report that as patients' multiple chemical sensitivity becomes chronic, they develop a parallel hypersensitivity to non-chemical physical stimuli. For example, severe intolerance to sudden temperature changes, electromagnetic currents, artificial light, and even sometimes sunlight. They begin having problems with photophobia.

Another important issue that we notice is the paradox of supplement reactivity. Clinically, antioxidant treatments such as high doses of glutathione or certain vitamins often cause severe and unexpected chemical sensitivity crises in these patients rather than improvement.

When you give these vitamin supplements to people who do not have chemical sensitivity, they usually improve. People with multiple chemical sensitivity sometimes cannot tolerate even these supplements, however natural they may be, even if they contain no additives. We have to give very small doses and even rotate the supplements rather than give them daily because their bodies cannot handle them and we cannot proceed with treatment. When this happens, it is a very characteristic sign that leads us to suspect that this person may have multiple chemical sensitivity.

Clinical patterns that are not fully reflected in official medical guidelines create many harmful consequences for this community. That's why it would be very important for what we've just discussed to be reflected in those guidelines.

Then there's the lack of understanding of comorbidities. If a patient with multiple chemical sensitivity reports that mobile phone antennas or Wi-Fi also makes them worse, the lack of solid literature on this overlap leads the general practitioner to misdiagnose them, thinking they have a psychological or even a psychotic problem. Imagine the serious mistake being made.

There's also treatment by trial and error because there are no evidence-based clinical guidelines for these secondary patterns. Specialists are sometimes forced to base their prescriptions on accumulated empirical experience rather than standardized protocols.

**Aaron Goodman:** Could you talk about the evolution of your own understanding of MCS? Have your ideas changed over the course of your career? Have you developed new insights from your interactions with people with the condition?

**Dr. Pilar Muñoz-Calero:** It's true that my understanding of multiple chemical sensitivity, a very complex illness, has evolved, not only because I've experienced it in my own body, and not only because I am a dedicated specialist who has spent many years studying and learning environmental medicine, but also because I have extensive experience and have been able to care for thousands and thousands of patients with multiple chemical sensitivity.

What has changed for me? First, I've learned something extremely important. The concepts of environmental medicine, for example, when realizing that someone exposed in a heavily polluted place sometimes feels worse when they are removed from those pollutants. Why? Because initially the body adapts. That is one of the most important concepts we need to understand and something I have observed throughout my clinical experience and my own life.

Tobacco is a very clear example. If someone smokes, initially they're not aware of the harm tobacco is doing to them, and they can tolerate environments and places where people are smoking. They stop smoking and suddenly they can no longer tolerate many of the places they used to visit. If they smoke a cigarette one day after several months without smoking, they cough again and develop symptoms again, and it feels as though they are worse.

Before I could manage, I smoked a pack of cigarettes and had no cough, and apparently nothing happened that my body showed, they say. I could also tolerate being in many places. Now I cannot be in those places. I cannot tolerate them, and I cannot even tolerate taking a puff of a cigarette. When sensitivity increases, we interpret it as getting worse, but that is not true.

Our body is simply beginning to lower its toxic load and improve, and its sensitivity begins to increase because fundamentally our body is sensitive. When we are children, we are sensitive. We have dulled that sensitivity and forced the body to adapt to many situations. This adaptation is important for specific moments, but not when it becomes chronic over time because it uses up all our resources.

Eventually, it exhausts all the resources we have in the body and we develop the illness. That's one of the things that most struck me and one of the things I have learned most about. Another thing I've learned or been reminded of through environmental medicine and my experience is what we call biochemical individuality.

Not everyone who smokes develops lung cancer. Not everyone who smokes develops recurrent bronchitis. Some people even die at 90 while still smoking. That does not mean it is not harmful to everyone, but not everyone responds in the same way. Sometimes people say to me, "If we were surrounded by as many pollutants as you describe, we would all be very ill already."

My response is that we are all actually doing worse than we think, but there is what we call biochemical individuality, and not everyone responds in the same way to exposure to different pollutants. I want to give you an example. Some time ago, I wanted to conduct a study, a clinical trial, and for that I needed a control group between 45 and 60 years old.

I could not find that healthy control group, healthy according to what I call healthy. There were functional people who took pills for diabetes, pills for thyroid problems, sleeping pills, pills to improve their mood, relaxants or anti-anxiety medication. To me, that is not a healthy person. We are changing the concept of what it means to be a healthy person.

A healthy person is someone who does not have to take medication and can, in some ways, express their best capacities. What else have I learned? I've learned that I do not know everything. Far from it. The more I study, the more I realize how much I still have to study.

People think that everyone with multiple chemical sensitivity has the same profile, but I completely disagree. Although they share a common basis and denominator, completely different things can appear specific to each person. After all these years, more than 25 years, and having seen thousands and thousands of patients, someone still comes into my clinic with a new symptom or a new reaction that no one has described to me before.

I never respond with disbelief or skepticism. I always think there's something real in what they are describing. I've learned to be much more humble as a physician. I've learned to put myself in patients' shoes and empathize with all of them. I've learned to try to help them and find meaning in what is happening to them, just as I have found meaning in my own illness and everything I have been through.

That has helped me live much more happily. It's interesting how many people with multiple chemical sensitivity tell me, "I do not regret everything that has happened because it makes me live much more consciously." Although it has involved pain and suffering and many people have withdrawn from my life, I have also learned that the people who truly loved and stayed with me. I've also learned that living consciously means living with much greater happiness.

**Aaron Goodman:** You've been listening to *The Chemical Sensitivity Podcast*. I'm the host and podcast creator Aaron Goodman. *The Chemical Sensitivity Podcast* is by and for the MCS community.

The podcast is generously supported by the Marilyn Brockman Hoffman Foundation and listeners like you. If you wish to support the podcast, please visit listen.chemicalsensitivitypodcast.org. Your support will help us continue making the podcast available and creating greater awareness about MCS. To learn more about *The Chemical Sensitivity Podcast*, follow the podcast on YouTube, Facebook, Instagram, BlueSky, and TikTok, and you can reach me at aaron@chemicalsensitivitypodcast.org.

Thanks for listening. *The Chemical Sensitivity Podcast* and its associated website are the work of Aaron Goodman and made possible with funds from the Marilyn Rockman Hoffman Foundation, supporting efforts to educate and inform physicians, scientists, and the public about multiple chemical sensitivity. The content, opinions, findings, statements, and recommendations expressed in *The Chemical Sensitivity Podcast* and associated website do not necessarily reflect the views and opinions of its sponsors.