A study of different types of asthma and how it is affected by different weather conditions

Abstract

This essay investigates factors affecting the PEF value and more generally how the asthma is affected, whether it may be positive or negative. More specifically this essay investigates how different types of asthma and weather conditions affect the PEF value.

The investigation is mainly based on experiments done with persons that have asthma, and one healthy to compare with. For the continuity all subjects are females, about the same age and physically active despite their asthma. The experiment consists of measuring the PEF value before and after an exercise, in this case running for five minutes. The type of asthma is also noted and the temperature and humidity is measured. A small part is also investigated using literature to find a theory to compare with. An interview was also performed with a doctor that is specialized within asthma.

The conclusions drawn from both research and experimenting is that emotions and stress affect asthma in a negative way, that is that the PEF value is lowered. What is also concluded is that asthma conditions in itself doesn't have any effect on the PEF value but the number of trigger factors and the severance of one's asthma does. Other things that was concluded is that the PEF value is affected in a negative way if both the temperature and the humidity is very low or very high, however the Swedish weather didn't show great variation in humidity and thus the results show no significant differences although the range in temperature was 20°C.

Introduction

It is only recently, three years ago to be specific, that I developed asthma and an interest in it; much of this is due to my own illness. It was in the summer break between my eighth and ninth year in school that I went to a camp during summer. After one week, I felt that whenever I went inside the cabin we were staying in I literally got a cold and had troubles breathing. One night it felt as if someone was sitting on my chest, preventing me from inhaling but more so from exhaling. It wasn't until the next day when I was forced to go to the hospital that they concluded that I had asthma, probably caused of some unknown allergy, since at that time I wasn't diagnosed with any allergy. Later it showed that I was extremely allergic to dust mites and that the cup had over flown during my stay at the camp and I had developed asthma due to this new allergy.

This was three years ago but despite my asthma I'm still physically active, I play football at least three times a week. I have learned to control my asthma but sometimes, depending on the weather, it becomes difficult to breathe. It was this that spurred my curiosity to see under which conditions the asthma was worsened. Was it due to extreme cold, dry or humid air or even high temperatures? Did the different types of asthma matter when it came to how severe one's asthma was? All of these question lead me to investigate how asthma is affected by different asthma conditions and the weather.

Another reason why I choose to investigate the effect of weather and asthma conditions was due to how much asthma there is in the world. This following diagram shows the prevalence of asthma during 2004.

As one can see the countries with the highest prevalence of asthma are Canada, USA, Great Britain, Australia, New Zealand, Brazil and Peru. What they all have in common is that they are some of the most industrialised countries in the world. With industrialisation also comes pollution which greatly increases the risk of developing allergies, which many scientists now believes can be a cause to allergy induced asthma. Also the asthma in general has increased since the 80's and allergy induced asthma is one of the more common asthma types nowadays.

What is also interesting concerning this diagram is that most of the countries have hot and humid or cold and dry climates. Toronto, in Canada, for example has a very shifting climate during the seasons. In winter it is extremely cold but during the summer it is very hot and humid, probably not the best weather for a person suffering from asthma.

Asthma

The word asthma means dyspnoea (shortness of breath). By just knowing what the word asthma means one can get a good understanding of what the disease is since asthma is when one has dyspnoea. Dyspnoea, however, is not the definition of asthma. The definition of asthma is not clear; it lacks a proper definition. This is due to the fact that one still doesn't know the main reason for asthma to develop since there are a lot of factors which contribute to the development of asthma. Furthermore there exist no laboratory analyses that are characteristic for asthma and a microscopic examination of the trachea and the lungs cannot be used for the diagnosis of asthma. What one can look at to define asthma is the symptoms and periods of dyspnoea and thus the international definition of asthma is the variation of dyspnoea which is a very vague definition in itself.

Cause and symptoms of asthma

Essentially asthma is an inflammation in the bronchi, the bronchioles and the alveoli. This inflammation is caused by allergies or other factors, called trigger factors since they trigger one's asthma. However it is important to note that it is not the cause of asthma. What can cause asthma is heredity, since if one's parents have an allergy or asthma the risk that the child will have asthma is greater than if the hereditary factor was non-existent. A trauma or a bad upbringing can also lead to asthma but it is uncommon.

What happens when one gets an asthma attack is that mucous starts to accumulate in the bronchi, the bronchioles, the alveoli and the mucous membrane starts to swell. This leads to a difficulty in breathing. Some experience a pressure over the chest as if someone had put a weight on top of the chest or that a strap is tied around the chest. Sometimes a whistling sound can be heard since the mucous membrane has grown too thick, making it hard for air to pass through. Some people get a coughing fit when an attack occurs. Due to the thickening of the mucous membrane the PEF value will decrease. PEF stands for Peak Expiratory Flow and it is the amount of air one breathes out under a forced exhalation.

Different asthma conditions

There exist different types of asthma; different asthma conditions. Although the existence of different conditions there are some common factors such as that the bronchi are easily irritated and extra sensitive to tobacco, smoke, dust and exercise. There are mainly three different conditions and they are distinguished by what factors triggers the asthma.

Exercise induced asthma

Exercise induced asthma is something everyone with asthma has since the bronchi are extra sensitive. What happens when one gets tired and breathless is that one starts to breathe faster and very dry air gets in contact with the bronchi which results in that the mucous membrane grows thicker and a whistling sound can be heard when you breathe or you can feel a pressure over your chest.

Virus induced asthma

Everyone with asthma has, to a certain extent, virus induced asthma which means that the asthma gets worse when one has a virus or a bacterial infection in the body. Just because one doesn't show any symptoms for an infection, it can still be in the body and it will affect one's asthma. However some people only have problems with their asthma when having a virus or a bacterial infection and thus their trigger factor is a virus or a bacterial infection which means that they have virus induced asthma. Most commonly a cold is the triggering factor for those with virus induced asthma.

Allergy induced asthma

Allergy induced asthma is of course that an allergy is the trigger factor to one's asthma; it could be several allergies which means several trigger factors. When exposed to a foreign substance the body recognizes the antigens as ‘not self' which basically means that they are seen a threat and thus the body starts to produce antibodies against this supposed dangerous substance. Since the body tries to fight this substance it can lead to the formation of mucous in the bronchi and thus it has triggered one's asthma. There are various substances that one can be allergic to such as dust mites, pollen, food, mould and animals, which are the most common allergies.

Psychology and asthma

During the 1940's asthma was defined as a psychological disease due to the correlation between mental health and asthma attacks. Stress and trauma can be a trigger factor to asthma and it is in 70% of the asthma population. However it is not the only trigger factor but when stressed or traumatized your asthma worsens. 18% of the asthma patients actually have psychological trigger factors.

Experiments on children have been made where the children are asked to imagine uncomfortable situations and the research showed that one can develop and asthma attack based on emotions. However normally an attack cannot be initiated by emotion solely but it can lead to a serious attack or worsen it dramatically. Experiments also show that when patients are asked to inhale something they believe will trigger their asthma, their asthma will be triggered albeit the fact that what they inhaled was something utterly harmless.

Furthermore a person with asthma that is indignant can start to hyperventilate which means that the air inhaled per minute increases and this can worsen if one is also exposed to cold weather or one's allergy. Also stress can affect this due to the fact that when one is stressed the muscles in the neck and abdomen is tense which contribute to hyperventilation. Through this a person with asthma can get caught in a bad circle.

How to measure asthma

Asthma is not something easily measured as weight and height. Since it is a disease, which makes it hard to breathe, one often measure the volume of air exhaled in litres per minute or per second. I have chosen to measure it in litres per minute, using a PEF meter which measures the PEF value. Therefore one can say that the PEF meter in general measures how well air passes through your lungs. When one's asthma is triggered mucus is formed in the bronchioles which make it harder to force out air which means that the PEF value will be lower when a lot of mucus has accumulated in the bronchioles. Therefore technically speaking the PEF meter measures how ‘open' your airways are, that is how free of mucus they are. An example of this is that a 10 year old boy came to the doctor with an asthma attack and his PEF value when he came in was 139 l/min and after inhaling  his medicine his PEF value had gone back to normal, 303 l/min. This took about half an hour.

The medicine usually consists of a variety of different chemicals that will either fight the inflammation or widen the bronchi. There are also medicines that have both the aforementioned functions, that is, they both work to diminish the inflammation and widen the bronchi. The time it takes for the medicine to show an effect vary and of course when one has an asthma attack one uses the medicine that takes the shortest time, which is about 3 minutes. This specific medicine usually widens the bronchi through working out the tension in the muscles in the bronchi and trachea. There are also medicines which work for a time span of 12 hours which is inhaled daily for long term purposes.

There are also different instruments to measure asthma. These are a PEF meter, as mentioned above, an airflometer and a minivitalograph. I chose to use a PEF meter since I already had one and it effectively measures what I was after, the peak expiratory flow and how it varies. All of the three mentioned meters are easily carried around due to their small size. They are also easy to use and are cheap to buy.

Investigation

The aim of this investigation is to see whether the asthma is affected by temperature, humidity and different conditions of asthma such as exercise induced, allergy induced or virus induced. This will be tested by having five people, four of them with asthma and one who is healthy, run for five minutes. This is not considered as dangerous for those with asthma since they are taking their medicines regularly and all of those with asthma actively exercise regularly and don't get any asthma attacks from playing football, which I assure is more strenuous work than running for five minutes. Also before the test we practised for about one and a half hour or two hours.

Equipment

1 PEF meter

1 stop watch

1 thermometer

1 instrument to measure humidity (measured in percent)

Method

The method is very simple but efficient. Firstly we started off by measuring the PEF value, to have as a reference when comparing with the other PEF values which was acquired later in the experiment. At the same time I measured the temperature and the humidity in the air with a so called weather station. After this the real test could begin. The test consisted of running at intervals for five minutes, were you run at about 90-100% of your capacity for 15 seconds then walk for 15 seconds and so on in 5 minutes. Directly after the running session we each blew in the PEF meter, waited for five minutes, blew a second time and waited for five more minutes. I measured the PEF value before exercise, directly after exercise, five minutes after exercise, ten minutes after and 15 min after exercise.

The test had five participants, one who was healthy ("Emy"), that is she has no asthma, and four with asthma, including myself.  We all have somewhat different asthma conditions and all are about the same age and female. "Therese" mainly has exercise induced asthma, "Ida" has virus induced asthma, I have allergy induced asthma and "Sandra" has all of these plus another lung disease.

As mentioned before this causes no harm to those with asthma since they all regularly take their medicines and all are active athletes thus they are all in good shape which further decreases the risk for a serious asthma attack.

It is very hard to control all variables since most of them are variables that I can't control due to the fact that I have test subjects and those I cannot control. For example I can't control Sandra's other lung disease but it doesn't surface very often so it should not interfere with my experiment. Other variables is the effectiveness of the PEF meter since some days you get good values and some days you get bad values due to the fact that one's asthma can vary very much. Neither can I control if they get a virus, which might not show but the fact that it's in the body will affect the result of the experiment. Furthermore I can't control their feelings and stress level which also affects the PEF value.

Results and discussion

All raw data can be found in the appendix and below is the processed data.

Graph 1: The mean PEF-value for each participant plotted against time

This graph shows the general change of the PEF value for all the participants. As we can see sometimes the PEF value in the end can exceed the one from the start which could be due to the fact that this experiment was done right after a two hour long practise and thus the participants haven't rested for a long time so the PEF value might not be at its peak. However, that the experiment was done right after a practise had its good points since everyone was warmed up and thus could perform better when running. Also the risk of a serious asthma attack had been lowered.

Looking at the graph generally we can see a drop right after exercise (which is 5 min after the experiment started), which is as predicted since the bronchi has come in contact with dry air and thus mucus has been formed and thus it would only be natural that the PEF value is lower directly after exercise. What may be surprising is that the healthy participant also has a drop but this is normal since usually a healthy person (a person without asthma in this case) can have a higher drop than a person with asthma. The difference is that the healthy person doesn't have any symptoms associated with asthma.

Studying each individual participant we can see that "Ida" has a decrease directly after the exercise and then she increases after resting. Due to the high increase after just 5 min rest we can deduce that it is likely not cause by her asthma since if it was, the increase would have been slower, but still an increase. However this is as expected since "Ida" has a virus induced asthma and as far as I know she didn't have a virus infection. She could have one lying dormant in her body but that won't affect the result very much.

"Sandra" on the other hand also had a decrease directly after exercise but her PEF value stayed low after five minutes of resting and then increased back to her normal value. This suggests that she was affected by her asthma and since she has all types of asthma (allergic, virus and exercise induced asthma) it is more likely that she will suffer from it.

"Therese" and I myself didn't show any big variations of our PEF value. This could be due to that I only have allergic asthma and that is triggered by dust mites, which obviously don't live outside. Thus I am not affected by it and since I take my medicine it is no surprise that my PEF value stays somewhat constant. Therese on the other hand has mostly exercise induced asthma but since she too takes her medicine regularly her PEF value is also somewhat constant.

Graph 2: For each temperature the PEF value directly before and after exercise is shown which allows one to see increases or no change at all in the PEF value

The humidity was also measured but since it was no great change in humidity (36%-46%) I chose not to display this in a graph. However the temperature and its respective humidity value are displayed in the following table.

Table 1: The humidity and temperature for each experiment that was carried out

Comparing the differences of the PEF value directly before and after exercise for each individual to each other we can see some correlations but not much. We can see that a decrease could be seen in all participants, greater for some and less for some, when the temperature was 15,2 °C. Another decrease for almost all participants was when the temperature was 19,0 °C. This of course doesn't suggest any major correlations since it depends on other factors too. The experiment performed when it was 16,6°C was carried out inside which could result in the fact that the air is not ventilated and thus we all experienced the air to be stifling. However when looking at the humidity it wasn't particularly dry which expel any correlation.

According to theory, which says that when the temperature is low (around 0°C) and the air is dry the PEF value will be affected in a negative way, it will decrease. The PEF value recorded for 0°C should therefore be the lowest. However the results say differently. This could be due to the fact that the humidity was as high as 39% which is very similar to the other values of humidity. This could suggest a correlation between temperature and humidity. That if the temperature and the humidity is both low an effect in the PEF value can be seen.

Unfortunately there isn't any more correlation between the different graphs and thus there is no more correlation between the effect of temperature and humidity on the PEF value. However according to theory one's asthma do get worse at high temperatures, which I guess is at 30°C. It is also affected by the humidity, very humid or very dry air will affect one's asthma too. Cold temperatures, below zero degrees, are also something that will worsen one's asthma. These conditions also apply to ‘healthy' persons.

Errors and weaknesses

There are numerous errors with the experiment, mostly due to the fact that some variables are not controllable. For example the fact that a virus can affect one's asthma is established but one is not able to control the fact that a participant can be infected and thus it will affect the results. Other variables that I was unable to control were the temperature and humidity of the air, I couldn't change the dependent variable as I liked. Looking at my data the temperatures are pretty close to each other, except for the zero degrees. The humidity showed no big changes and thus it doesn't give a good view on how the PEF value actually will vary, according to theory. I know from my own experience, and through theory, that the PEF value will be affected by cold weather, such as zero or minus degrees. The humidity, as mentioned before, was close in value thus it didn't give a good overview since an effect in the PEF value will only be noticeable when the it is very humid, about 60-70%, or when it is very dry air, probably below 25%.

Some other weaknesses with the experiment is the fact that Emy, the healthy participant, didn't have the same blowing technique due to the simple fact that she has never done this ...