oak-alley

Ahwatukee Oak Alley

I attended medical school in New Orleans.  Along with great food, music and the rich culture and history, one of my fondest memories was the magnificent Southern Oak trees.

These ancient giants, some dating back to the Civil War, with trunks the size of a Volkswagen beetle, hanging with moss, framed an idyllic image of the old south.  They are beautiful trees but they are also one of the major causes of spring allergy problems throughout the south.

When I moved to Arizona and started an allergy practice, I was sure of one thing:  I would not have to worry about Southern Oak allergy problems in Phoenix!

I was wrong.

I have known that there are several varieties of Oaks native to Arizona, the majority of which live at higher elevation in the state, and rarely in Phoenix.  But certainly, there were no trees resembling the Oaks I knew from the south, growing in a typical, low water use, desert landscaped yard in Ahwatukee!

Souther Oak Trees Lining Lakewood Drive in Ahwatukee

Oak Tree Pollen

And yet, if you take a drive around the lakes of Lakewood, in Ahwatukee, (as I did on my bike a few weeks ago), you will find the entire seven mile stretch lined with mature Southern Oak trees.  No hanging moss or women in antebellum dresses swinging on porch swings, but most definitely full of pollen.

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Arizona Olive Trees: Life Will Find a Way

Reproduction is one of the most powerful forces in nature.

In the plant world, this power is on grand display every spring in the form of fantastic flowers and although flowers look and smell nice,  it’s all business for the plant. When plants require the services of insects such as bees to deliver pollen from one plant to another, those services are advertised and paid for in the currency of attractive flowers and sweets (nectar).   This is an efficient system with little wasted pollen.

Other plants are not so economic and literally toss their goods to the wind, producing a dust storm of pollen in hopes that out of the enormous quantity of pollen produced, some will reach their mark.

Wind Pollinated Problems

This is where we come in.    All this blowing pollen gets on our skin, in our eyes, up our noses, and down our windpipes, causing itching, sneezing, dripping, and wheezing.

The Arizona Olive Tree: Public Enemy Number One

A popular imported landscape addition since around the 1930s, the Olive tree has become one of Arizona’s’ most notorious contributors to our seasonal allergy misery. The Olive tree is so sensitizing that planting fruiting Olives has been discouraged or banned in Phoenix and Tucson since the 1960s    Nurseries and landscape companies are not allowed to sell or plant them.

And yet, the Olive tree is an attractive tree and still very popular, and so to get around the planting restriction, “non-fruiting” (less pollen and less fruit) varieties, such as the San Hill Olive, were developed and sold by nurseries as a less messy and hypoallergenic alternative.

If you wanted a nice, hypoallergenic shade tree in your yard in Ahwatukee you just asked your landscaper or nursery for a Swan Hill Olive and you were set.

Perhaps not.

Ahwatukee Olive Trouble

One problem is that there have been reports of nurseries in the East Valley selling conventional Olive trees as the non-fruiting variety.  You probable could not tell the difference in a newly planted tree and by the time it became clear that your supposedly impotent hypoallergenic purchase was actually quite capable of doing it’s part to propagate the species, yanking a mature tree out of the yard might not be an appealing option.

The other problem (which is what made me think of that phrase from Jurassic Park) is that non-fruiting Olive trees may revert back to their natural, virile state.   This was described to me by a landscape business owner in Ahwatukee who has witnessed this transformation in trees that he knew to be true San Hill varieties, but which, in time, found their true, pollinating machismo, as it were.

Mother nature is not easily fooled.

Swan Hill Olive Tree With Suspicious Pollen Clusters

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If You Are Sneezing in Ahwatukee and It’s February – It’s the Ash Trees!

I was visiting a friend last week who lives next to Altadena Middle School. He has two very large, stately trees in his back yard that provide great shade during the summer. In February however, there are no leaves on the trees. Just packets of pollen clusters. The branches are heavy with them.

Ash Flower

Ash Tree Flower

 

 

 

 

 

 

 

These Ash trees also line the sports fields of Altadena. And once you start to look for them, they are everywhere: in local parks, schools, green belts, and your neighbors yard. All heavy with the same pollen sacks. I took a few pictures while riding my bike and found a large number of Ash trees in Vista Canyon Park next to Desert Vista High School.

Flowering Ash Trees, Vista Park, Ahwatukee, Phoenix

Flowering Ash Trees, Vista Park, Ahwatukee, Phoenix

 

 

 

 

 

 

 

Interestingly, the logo for the Phoenix Parks and Preserves Initiative is an Ash leaf !

Ash Leaf Logo

Phoenix Parks and Preserves Ash Leaf Logo

 

 

 

 

 

 

 

More than half a century ago, tree pollen counts in Phoenix skyrocketed. The culprit, the popular Olive tree. From an allergy standpoint the Olive tree is a monster. March through May, Olive pollen fills the air and is incredibly sensitizing with many new residents becoming allergic after just one season of exposure.

So notorious is the Olive for causing allergy problems that it has been banned in a number of cities including Tempe and Phoenix and so you will not see many in the newer communities in Ahwatukee. Unfortunately, the Olive happens to have a close allergy cousin, the Ash tree. Most people who react to Olive on allergy testing will also react to Ash, a form or cross-reactivity. Some allergy-control progress may have been made in limiting Olive tree planting, but this progress has likely been lost in the rising popularity of the Ash tree.

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“Didn’t We Do This Last Year?”

I am reposting an article that I wrote (almost to the day) a year ago.  At that time we were experiencing an unusually early “spring” allergy season starting in late January.  Well, here we go again.

The Ash trees began pollinating two to three weeks earlier than usual again this year and, by the looks of things, ragweed pollen will be making an appearance much earlier as well.   We can thank the relatively wet winter and beautiful warm weather this February, and I suppose one could evoke the “global warming” excuse at some point.   Regardless, we are certainly in for a potent spring.

Part One:

When we think of allergy season, fall and spring comes to mind, but not so much winter.  Yet this December, January, and now into February, patients have been coming into our allergy clinic in the suburbs of Phoenix complaining of some of the worst allergy symptoms all year.  Typical complaints include sneezing, itchy nose, and particularly, very itchy eyes.

Aligator Juniper

Aligator Juniper Payson, Arizona

When patients undergo testing for allergies, many show sensitivity to a number of different allergens such as plant pollen, mold, foods, and animal dander.  However, in the case of the winter allergy sufferers, the majority show sensitivity to only one thing: juniper, or more specifically, Cupressaceae.

The Cupressaceae are a family of evergreen conifers found throughout the world. Arizona is home to a number of native species of cupressaceae including Rocky Mountain Juniper (Juniperus scopulorum), Utah Juniper (Juniperus osteosperma), One Seed Juniper (Juniperus monosperma), Alligator Juniper (Juniperus deppeana) and Arizona Cypress (Cupressus arizonica).

Although Phoenix has a number of ornamental varieties of Cupressaceae used in landscaping, the majority are found at 3000-7000 feet elevation and cover millions of acres surrounding Phoenix on all sides.    When conditions are right, a large amount of cupressaceae pollen finds its way into the valley.  One of the chief offenders is Arizona Cypress which is very prevalent in the higher areas surrounding the valley and produces  pollen November through March.

The pollen produced by the different varieties of Cupressaceae cross react with one another, which means that if you are allergic to one you will be allergic to all.  Mountain cedar (Juniperus ashei) is the leading cause of respiratory allergy in South Texas and affects so many with severe allergy symptoms that it has been given it’s own diagnosis, “cedar fever” .

Part Two:

While walking my dog several weeks ago, I noticed something unexpected; a number of ash trees in full bloom.   This was unexpected because it was the first week of February and ash trees usually pollinate later in the month.  It was also unexpected because this was near a school in the Foothills of Ahwatukee were the ash trees are supposed to be of a less allergenic variety.   This is in distinction from the Arizona Ash, Fraxinus velutina, which is notorious for it’s prolific production of allergenic pollen. For this reason landscapers have been discouraged from planting Arizona Ash trees for a number of years although they are very numerous in older communities such as the Warner Ranch area as well as old Ahwatukee and Tempe.

 

ash-pollen

Ash Tree Pollen Clusters Ahwatukee

Ash trees are in the same family as olive trees, possible the most allergenic tree in Phoenix, and so people who are allergic to one will be allergic to the other

The ash trees are pollinating a full two to three week early this year, probable because of the warm weather.  This along with large amount of Arizona Cypress and Juniper pollen in the air is creating a very difficult winter for people with allergies.

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Arizona Air Quality: Ozone and Outdoor Exercise

I am discussing air quality in Arizona, particularly as it affects patients with allergies and asthma. Previously, one of the most important pollutants, Ozone was discussed and in this post I will continue with some of the special problems associated with ozone exposure and outdoor exercise.

For a number of reasons, athletes are particularly vulnerable to the adverse effects of air pollution.  A distance runner training for a marathon or a cyclist getting ready for a century ride, will spend hours every day inhaling huge volumes of air during the course of a workout. In fact, a cyclist may inhale 80 liters of air a minute for an hour during a race.

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Cyclists on South Mountain. Notice haze sitting over Ahwatukee

Exercise not only increases the volume of air that we breathe, but the high velocity of air movement sends particles deeper into the lungs.  Blood supply to the lung in also increased to absorb more oxygen, which will also allow greater absorption of any contaminants found in the air. In addition, many athletes breath through there mouth when exercising, bypassing the filtering effect of the nose.

The end result is that during exercise, the tissues of the nose, sinuses, airways, and lungs endure intense exposure to particulate and vapor pollutants such as ozone.  Obviously the greatest risk of exposure to ozone is likely to occur when exercising in the city close to traffic, particularly in the summer when the sun is shining, but because ozone can travel great distances, you cannot escape it’s effect if you live and exercise in a more rural part of Arizona, such as Ahwatukee or Cave Creak.

Because of the increased exposure to the oxidizing effects of ground level ozone with exercise, the cells lining the respiratory track can be injured. In fact, studies have shown that exposure to ozone can cause the lining of the airways to become “leaky” allowing other particles in the air such as pollen and mold spores to have greater access to our immune system, aggravating and even possible causing, allergies and asthma.  Many studies have shown that children living close to automobile traffic have increased lung problems including asthma.

Long distance runners have been found to have reduced mucocilliary function in the nose. The mucocilliary system helps to clear toxins and debris from the respiratory system and is important in our defense against infection, so a weakness in this system increases the potential for further injury and damage to the airways from air pollution.

Exposure to ozone can cause a variety of immediate symptoms including nasal and throat irritation, coughing, wheezing, shortness of breath, and pain with deep inspiration.  In addition, a measurable decrease in lung function and exercise performance can occur which worsens the longer you exercise.    Ozone exposure can cause inflammation in the airways resulting in painful breathing.  This combination of reduced lung function and painful breathing can significantly limit an athlete’s ability to perform.

Interestingly, the respiratory symptoms associated with ozone exposure mimic exercise induced bronchospasm.  Unlike EIB however, ozone related symptoms do not improve with asthma medications such as albuterol.  In some cases, ibuprofen and other non-steroidal anti-inflammatory agents have been helpful in reducing the pain, coughing, and breathing limitation associated with ozone induced inflammation.

Air pollution

Air Quality in Arizona: Ozone

I will continue the discussion on air quality in Arizona, particularly as it affects patients with allergies and asthma, beginning with one of our most important pollutants: ozone.

diagram-29982_1280 (1)Ozone in the upper atmosphere is our friend.   This thin layer of gas floating between 6 and 31 miles above the earth’s surface protects life on our planet by filtering harmful ultra violet rays from the sun.

Ground level ozone is another story.  This insidious byproduct of automobile exhaust can damage living tissue just as it’s relative in the upper atmosphere protects it. Even the chemical structure of ozone looks like it would be friendly enough: it is just like oxygen, O2, with one more oxygen atom added to make O3 -a super oxygen!

But as vital as oxygen is to sustain human life, too much can be deadly.  To understand why, think about the effect of oxygen on a forest fire on a windy day or what happens to an unpainted iron fence -even in Arizona where it rarely rains.

Rusty BoatWhen wood burns or iron rusts, oxygen is at work in a process called oxidation. Oxidation can turn a battle ship into a heap of rust and kill all the bacteria and algae in your swimming pool.

In fact our immune system uses the deadly effects of oxidation to fight off disease.  Our white blood cells release powerful oxidizing chemicals like hydrogen peroxide and what are called, “reactive oxygen species,” or ROS, that kill and even digest invading pathogens.  This is great when you need to get rid of an infection, but we don’t want these chemicals loose in our bodies digesting us.090114_2215

To keep our white blood cells from eating holes in our lungs and liver, anti-oxidants are produced that are capable of neutralizing the oxidizers and preventing damage. Important antioxidants include vitamin A, vitamin E, beta-carotene, vitamin C, and glutathione as well as many other compounds found in food, especially vegetables and fruits.

When chronic inflammation occurs as a result of injury, infection, allergies, or immunologic processes, excessive amounts of these oxidizing chemicals are produced creating a condition called “oxidative stress”.  This stress can contribute to the pathogenesis of a wide variety of disease states including heart failure, atherosclerosis, and cancer as well as to the normal process of aging.

The role of diet and vitamin supplementation in the treatment and prevention of chronic disease is an important subject and one that I will review in more detail in a later post.   For now, the point I would like to make is that oxidative exposure from external sources can overwhelm our anti-oxidant resources and can contribute to the development and exacerbation of chronic disease.

Which brings us back to ozone.

Ozone is a killer oxidizing agent – powerful enough to be used commercially to sterilize water supplies. It is definitely not something you want to spend much time inhaling.  Exposure above as little as 100 ppb (parts per billion) can be harmful, causing symptoms such as nose, eye, and throat irritation, coughing, wheezing, shortness of breath, painful breathing, nausea and headache, and has been linked to increased incidence of asthma, bronchitis and heart disease.  Long-term exposure has been linked to increased risk of death from lung disease.

Untitled design (36) (1)According to the Maricopa Air Quality Department, ozone levels in our area are can reach unhealthy levels on “hot, sunny days when there is little wind”, which pretty much describes most days in Phoenix from May until October. For example, about a week out of the month of July, 2013 were under a high pollution advisory and health watch for ozone. This year the American Lung Association ranked Phoenix as the 11th most polluted city in the US for ozone.

In recognition of the adverse health effects of ozone, air quality guidelines have been established by the World Health Organization, European Union, and the US Environmental Protection Agency (EPA).   In 2010, the EPA announced proposed revisions to the National Ambient Air Quality Standard (NAAQS) for ozone with the following statement:

EPA proposes that the level of the 8-hour primary standard, which was set at 0.075 μmol/mol in the 2008 final rule, should instead be set at a lower level within the range of 0.060 to 0.070 μmol/mol, to provide increased protection for children and other ‘‘at risk’’ populations against an array of ozone – related adverse health effects that range from decreased lung function and increased respiratory symptoms to serious indicators of respiratory morbidity including emergency department visits and hospital admissions for respiratory causes, and possibly cardiovascular-related morbidity as well as total non- accidental and cardiopulmonary mortality…

In addition, the Air Quality Index (AQI) was developed by the EPA to explain air pollution levels to the public. Using this scale, eight-hour average ozone levels of 85 to 104 nmol/mol are considered “unhealthy for sensitive groups,” 105 nmol/mol to 124 nmol/mol as “unhealthy,” and 125 nmol/mol to 404 nmol/mol as “very unhealthy.. The current AQI for Maricopa county and surrounding areas can be found at

http://alert.fcd.maricopa.gov/alert/Google/v3/air.html

Ozone exposure can have a significant negative impact on lung function, particularly in athletes involved in outdoor sports, a topic I will explore further in the next post.

South Mountain Sunset

Arizona Air: The Good the Bad and the Ugly

Phoenix is a wonderful place to live if you enjoy spending time out of doors.  However, there is a catch. The conditions that make for our predictable-practically-perfect weather (at least in the winter and spring) has also led to some serious air quality issues.

Every year the Arizona Department of Environmental Quality releases a number of high pollution advisories warning Arizonans that it may be unhealthy to venture out of doors, particularly if you have a medical condition such as asthma.  July and August show the highest number of “very unhealthy days”.  In fact in July 2013, there were seven “very unhealthy days” reported.

Over the next few posts, I will review some of the unique conditions that make up our Arizona environment and spend some time on the major components that make up the “poor air quality” reported by the Arizona Department of Environmental Quality

To begin, one thing is obvious: Phoenix is a desert.  Like most deserts, our climate is characterized by high pressure conditions that camps out over the region for extended periods of time resulting in warm (and hot!), dry, and generally clear conditions.   Half of the yearly rainfall occurs during the winter when brief pacific storms move through the region.   During the monsoon season, from July to September, moister from the south brings higher humidity and most of the remaining rainfall, often in the form of violent thunderstorms.

During late fall to early summer, high pressure sits over the region like a glass lid, repelling the volatile weather fronts that plaque much of the United States and keeping the interior toasty warm and dry.  What little wind does occur is generated by local temperature and elevation variations.  This, along with the extremely low humidity during this time of year, allows airborne particles -dust, pollutants, pollen-to drift in the atmosphere for a very long time rather than being cleaned away by rain or ocean breezes.

Conditions change somewhat during the second half of the summer when high pressure travels north a bit allowing monsoon moisture to move into the valley.  The increased volatility in the local wind patterns not only produces thunderstorms (and the hope of rain) but also massive dust storms.  These giant walls of dust can transport appreciable quantities of organic as well as inorganic material as they move across the valley.  Exposure to these clouds of organic bits of plants, mold and who-knows-what-else (think Maricopa feed lots) can trigger severe allergy and asthma attacks.  An analysis of material from dust storms in Tempe showed they contain an average of 11% organic material.

Although monsoon storms have the potential to bring rain and some clearing of the air, summer is the time when ozone becomes a problem. That will be the topic of my next post.

Exercise Induced Bronchospasm: Treatment

As every athlete involved in an aerobically taxing sport knows, effective breathing can be key.  Muscles will not keep working  (and you won’t keep going) if you can’t breath. Oxygen delivery to working muscles depends on several factors, but the ability to rapidly move a large volume of air in and out of the lungs is critical.   When oxygen demand exceeds supply, an effort can continue for only a short period before you must slow down or stop.   No gas, no go. That’s the law!

Exercise induced bronchospasm (EIB) causes tightening of involuntary muscles surrounding medium to small airways.  This narrowing of thousands of tiny airways limits the rate at which air can be moved into and out the lung.  The “button” that turns on brochospasm in susceptible athletes is a receptor in the lining of the airways that respond to rapid changes in the temperature and humidity of the airway, conditions that frequently occur with such sports as running and biking out of doors.   Rapidly breathing cold, dry air is a particularly strong trigger.  Fortunately, the airways not only have an “on” button that when pushed tells the airway muscles to tighten, but also an “off” button that will relax the tightened airways, relieving the obstruction and allowing air to flow freely.  This muscle- relaxing button is called a beta-receptor.   Not only are these beta-receptors found throughout the airways, but also in the heart and nervous system where, as you might imagine, they have different effects.

The most important medication used in the treatment of asthma is albuterol, a beta agonist.  In other words albuterol “pushes” beta-receptor buttons causing rapid relaxation of the airway muscles and bronchodilation.  Because of the beta-receptors in the heart and nervous system, albuterol can also cause an increase in heart rate and a sensation of nervousness.

Not surprisingly, the most frequently used treatments for EIB is albuterol.   Two inhalations of albuterol fifteen minutes prior to an exercise cession will provide prevent bronchospasm for up to four hours.   Albuterol can also be used when needed to provide rapid relief of asthma symptoms such as wheezing, chest tightness, and shortness of breath within five minutes.   Albuterol is so effective in preventing exercise-induced bronchospasm that response to treatment with albuterol is often used as a test to confirm EIB.   If a patient is suspected of having EIB but does not improve with albuterol before exercise, an alternative diagnosis should be considered.

Albuterol is very effective in preventing symptoms of EIB but it does have limitations.  In athletes who train daily, albuterol can become less effective over time so that, not only does it become less effective in preventing EIB but can also become less effective during an asthma attack.  This is unlikely to be a problem if albuterol is not used daily.

Because of the concerns associated with daily use of albuterol, it is suggested that an athlete with EIB who exercises daily use an inhaled corticosteroid in addition to the albuterol.  Although steroids are not bronchodilators, they are very effective controllers of inflammation and are felt to maintain the effectiveness of albuterol after several weeks of daily use; inhaled steroids may also effectively control EIB without the need for albuterol.

Another medication that has been used for EIB is monteleukast or Singulair.   Monteleukast is preferred by many because it is a tablet (chewable for children) rather than an inhaler, can be used daily, and does not have the concerns associated with an inhaled steroid.  It does not benefit all who use it and many find it significantly less effective than albuterol or an inhaled steroid.

Albuterol is called a short-acting-beta agonist (SABA) because of it relatively short (four-six hours) duration of action.  Long-acting-beta agonists are also available which provide protection from EIB for up to 10 hours.   This would seem to be ideal for many athletes although because of the concern about loss of effectiveness with daily use and the possibility that this kind of medication could mask a worsening asthma attack, it has been recommended that LABAs not be used without the concomitant use of an inhaled corticosteroid.  Fortunately, there are several products available that combine an inhaled corticosteroid with a LABD including Advair, Serevent, and Dulera.   The LABD in Serevent and Dulera can work as quickly as albuterol and can therefore be used as a very effective daily treatment for EIB.

Several non-pharmacologic treatment options may be effective in some with EIB. These include warming up slowly before a hard workout to create a “refractory” state in the airways, preventing bronchospasm and wearing a mask to limit exposure to cold, dry air.

For patients with allergies who also have EIB, adding an antihistamine may be helpful.

Exercise Induced Bronchoconstriction: Diagnosis

On the surface, making a diagnosis of exercise-induced bronchoconstriction (EIB) should not to be too hard. After all, having an asthma attack while exercising would make the diagnosis fairly apparent.  However, as I mentioned earlier, self reported symptoms associated with exercise such as shortness of breath and chest tightness can be associated with a number of causes, both respiratory and non-respiratory, including just being out of shape.   In fact, in one study, approximately half of elite athletes with symptoms suggestive of EIB were found to have normal lung function.  Even more interesting is the fact that nearly half of the athletes who did not feel that they had EIB in fact tested positive for it.

Because symptoms alone are not sufficient, an objective test is required to make an accurate diagnosis.  The best tests for EIB either directly measure airway changes during exercise or produce the inflammatory changes in the airways that occur in patients with EIB and therefore serve as a surrogate for an exercise challenge.

An exercise challenge starts with a baseline pulmonary function determination with serial lung function measurements taken following a period of prescribed exercise.   A typical protocol might include running on a treadmill for 6-8 min at 80-95% of an athlete’s calculated max heart rate.  This level of exercise requires significant effort but is required to produce changes associated with EIB in highly trained athletes.  Following the effort, lung function values are recorded at 5, 10, 15, and 30 minutes and compared with the pre-challenge numbers.  A 10% or greater drop in lung function persisting for at least 15 minutes after exercise has stopped is diagnostic of EIB.

Because EIB is triggered in some athletes by inhalation of cold, dry air, a weakness of an exercise challenge on an indoor treadmill is indoor humidity that may be significantly different form the sport environment.  For this reason, sport and environment specific challenges (field challenges) have been found to be more sensitive than tests run in controlled indoor environments.  This is particularly true for those involved in winter sports such as ice skating and skiing and may very well be important for athletes who train in a desert environment such as Phoenix.   In some, the level of intense exertion present in competition may not be reproduced exercising in a calm, indoor setting, producing falsely negative results.

Several alternatives to an exercise challenge have been developed including what is called Eucapnic Voluntary Hyperpnoea or EVH.  In this test an athlete breathes a specially formulated, dry, gas mixture at a rapid rate to replicate the conditions of a hard exercise cession.  This is currently the only test recommended by the International Olympic Commission to identify EIB in Olympic athletes.  Unfortunately, the test requires specialized equipment and is not without some risk of precipitating a severe asthma attack.  For this reason the test is not widely available, in spite of the IOC recommendations.

Although an objective diagnostic test for EIB is recommended when possible, another approach to is to treat the athlete with an asthma regimen and see if symptoms improve. I’ll discuss more about this in the next post when I review treatment of EIB.

Exercise Induced Bronchoconstriction: What, When, and Where

Exercise-induced bronchoconstriction or bronchospasm (EIB) is defined as acute airway narrowing occurring as a result of exercise.  In the previous post I discussed that exercise, particularly vigorous, aerobic exercise, frequently triggers symptoms in patients who have a diagnosis of asthma but can also cause asthma symptoms, wheezing, shortness of breath, cough, and chest tightness, in athletes who have never had asthma.

Feeling very short of breath after a hard aerobic workout does not mean that you have asthma.  More often it means you are a bit out of shape.  So how can we tell the difference between symptoms caused by going too hard and symptoms caused by EIB?

One difference is that symptoms of EIB do not track with heart rate.  Getting out of breath because of de-conditioning or exercising beyond your aerobic capacity occurs when you are not able to deliver enough oxygen to your muscles to meet their demand.   Your heart beats rapidly and you breath faster and deeper to try to deliver more oxygen to meet the demand. But once you reach your limit, oxygen-starved muscles cannot keep going and you have to slow down or stop.  When you do, your heart rate and breathing slows and the shortness of breath and sensation of air hunger quickly improves.

With EIB however, symptoms do not usually begin until well into an exercise cession, and most importantly, will continue for 30 to 60 minutes after exercising has stopped.

In fact, it is believed that rapid breathing during exercise has a cooling and drying effect on the lining of the airways, which in patients with EIB triggers inflammation.  This inflammation is similar to an allergic asthma attack and will continue after exercising has stopped.  Because cooling and drying of the airways triggers inflammation, symptoms of EIB are more likely to occur during periods of exercise out of doors when the air is cold and dry.   Other environmental conditions that have been found to contribute to EIB include high ozone and particulate levels in the air.

Cold, dry air with high ozone and particulate levels describe conditions frequently encountered in Phoenix and other desert communities in the fall and winter. Athletes involved in aerobic sports requiring high respiratory volumes over an extended period of time such as runners and cyclists are most vulnerable. In fact, exercise induced bronchoconstriction occurs in up to 15% of distance runners.

I will review diagnosis and treatment options for EIB in future posts.