What is asthma?
Asthma is a condition characterized by inflammation of the lining of the airways and intermittent spasm of the underlying smooth muscle. The symptoms include shortness of breath, chest tightness, cough and wheezing. When a person has asthma, the breathing tubes are sensitive. Breathing tubes can react to smoke, pollen, dust, air pollution, allergies or many other triggers. In most people, the effects of asthma is reversible with inhalers or rest (depending on the degree of bronchoconstriction during the attack). An asthmatic person will often have normal lung function between attacks. To learn more about asthma, click here.
How many people are affected by asthma?
Asthma can develop at any age. Approximately 14.6 million people have asthma and 1.4 million of those people are 65 or older.
What is occupational asthma?
Occupational asthma is asthma that is caused or exacerbated by agents in the workplace.
More is known about the cause of occupational asthma (occupational asthma) than other forms of asthma. Asthma is often the result of allergy to an inhaled dust or vapor in the workplace. Its symptoms include cough, wheeze, chest tightness and shortness of breath which often improves on weekends, days off work, or longer holiday.
Causative agents for occupational asthma include:
- Isocyanates (e.g. in twin-pack spray paints)
- Hardening/curing agents e.g. anhydridess
- Rosin (colophony) fumes from soldering flux
- Dusts from various cereals (including flour)
- Animals such as mammals (rats, mice) but also arthropods (such as locusts)
- Wood dusts – various e.g. Canadian red cedar
- Aldehydes e.g. formaldehyde or glutaraldehyde
- Cyanoacrylates (as in “superglue”)
Fire fighters that were not asthmatic before employment, but developed asthma in their work, should be evaluated for possible causes. Occupational asthma and other reactive airway diseases (RADS) may result from exposure to chemicals, hazardous spills, and combustion smoke. The contribution to the causation of asthma by irritant gases such as sulfur dioxide, nitrogen dioxide and ozone is still unclear, although it is known that these substances can certainly aggravate symptoms in those who are already asthmatic.
In the home, exposure to allergens from house dust mites can be a contributing factor in the development of asthma as well as a cause of its symptoms. Other allergens from pollen, molds, animal dander etc can cause asthmatic symptoms. Outside the home in the general environment increase in asthmatic symptoms has been attributed to exposure to soy bean dust and to rape seed oil.
Can asthma be treated?
Yes, asthma can be successfully treated. Most of the time it is reversible with medication. There are many types of asthma medications.
There are two main categories of medications: controllers, and relievers. Relievers are medications that can help relieve asthmatic symptoms. Controllers are medications that prevent the occurrence of these attacks.
Relievers are medications that provide immediate relief for asthma symptoms. Examples of relievers that are use commonly are inhaled beta-agonists such as: Albuterol (Proventil, Ventolin), Pirbuterol (Maxair Autohaler). Two to six inhalations of the drug from a metered dose inhaler can be used as needed for acute symptoms or pre-exercise to block exercise-induced bronchoconstriction (tightening of the bronchial tubes).
Controllers are medications that are used daily to control and prevent asthma attacks. Controller medications can be in the form of daily inhalers or pills.
Inhaled corticosteroids. There are many brand names of inhaled steroid of varying potency. Beclomethasone diproprionates, fluticasone (Flovent), and budesonides (Plumicort or Turbuhaler) are common generic names for these inhaled steroids.
Leukotriene modifiers include montelukast and zafirlukast, and zileuton are indicated for long-term control and prevention of symptoms in patients. There is at least some additive effect with inhaled corticosteroids. No toxicity or drug interactions has been described. Since some of these drugs are new, long term side effects may not been well-studied. Zileuton may cause side-effects associated with elevation of liver enzymes.
Systemic corticosteroids (prednisone). Higher doses of prednisone may be used in the emergency room or in the hospital for asthma attacks that are very severe and that may turn out to be an impending or actual respiratory failure. For outpatient use, patients may be continued on that for sometime as part of the maintenance therapy if their asthma is bad enough. Side effects may develop during the course of therapy. These may include insomnia, mood or behavior changes, musculoskeletal pains, or bloating. Dosage should be continued until the patient is free from symptoms and signs of asthma. The mean duration of therapy is 7 days, with a usual range of 5 to 10 days. Dosage should be discontinued without tapering.
When used as maintenance medication, dosages of 20 to 40 mg of prednisone or prednisone on alternate mornings are generally needed and tolerated. Dosing should begin high and then be reduced to the lowest dose consistent with control of asthma. Sometimes, your physician may use this medication for short term and then substitute it with inhaled corticosteroid, or increased the dose of your inhaled corticosteroid as they are similar in terms of therapeutic effect but with lesser side-effects than systemic corticosteroids.
Salmeterol (Serevent and Diskus or salmeterol with fluticasone (Advair Diskus). These are long-acting beta agonist. Salmeterol is used for the purpose of bronchodilation (opening up of the narrowed airways). However, the half-life of this medication is long so it is not use to provide acute relief. It is used as a supplement bronchodilator for people who needed frequent use of beta-agonist to control their symptoms. It is also perscribed for those who have night time symptoms that are not controlled by the current medications.
Anticholinergic drugs (e.g., atropine and ipratropium bromide, Atrovent) block reflex bronchoconstriction due to irritants or to reflux esophagitis. The role of anticholinergics in day-to-day treatment of asthma has not been defined.
Inhalers: There are many ways of delivering these medications. Inhalers (Figure 1) or puffers are the most common form of delivering medication. If the attacks are severe enough, nebulizers (Figure 2) may be use as delivery device to get the medications down deeper into your lungs.
How do I monitor my symptoms?
A peak flow meter is a device that measures how well air moves out of your lungs. During an asthma episode, the airways of the lungs usually begin to narrow slowly. A peak flow meter may indicate a narrowing of the airways hours—sometimes even days—before asthma symptoms occur. A peak flow meter is most helpful for patients who must take asthma medicine daily.
Taking medicine early (before symptoms), may stop the episode quickly and avoid severe asthma episode. Peak flow meters are also used to check the severity of asthma. Peak flow meter and daily diary have been proven to be useful to:
- Learn what makes your asthma worse
- Decide if your treatment plan is working
- Help your doctor decide when to add or stop medicine and to track the status of your asthma
- Decide when to seek emergency care if your peak flow drops to a dangerous zone
Figure 4 A Peak Flow Meter that help guides patient self-monitoring of asthma severity.
How to find your personal best peak flow number?
Your personal best peak flow number is the highest peak flow number you can achieve over a 2- to 3-week period when your asthma is under good control. Good control is when you feel good and do not have any asthma symptoms.
Each patient’s asthma is different, and your best peak flow may be higher or lower than the peak flow of someone of your same height, weight, and sex. This means that it is important for you to find your own personal best peak flow number. Your treatment plan will be based on your own personal best peak flow number.
To find out your personal best peak flow number, take peak flow readings:
- At least twice a day for 2 to 3 weeks.
- When you wake up and between noon and 2:00 p.m.
- Before and after you take your short-acting inhaled beta2-agonist for quick relief, if you take this medicine.
- As instructed by your doctor.
The Peak Flow Zone System
Once you know your personal best peak flow number, your doctor will give you the numbers that tell you what to do. The peak flow numbers are put into zones that are set up like a traffic light. This will help you know what to do when your peak flow number changes. For example:
Green Zone (more than ___ L/min [80 percent of your personal best number]) signals good control. No asthma symptoms are present. Take your medicines as usual.
Yellow Zone (between ___ L/min and ___ L/min [50 to less than 80 percent of your personal best number]) signals caution. You must take a short-acting inhaled beta2 -agonist right away. Also, your asthma may not be under good day-to-day control. Ask your doctor if you need to change or increase your daily medicines.
Red Zone (below ___ L/min [50 percent of your personal best number]) signals a medical alert. You must take a short-acting inhaled beta2 -agonist (quick-relief medicine) right away. Call your doctor or emergency room and ask what to do, or go directly to the hospital emergency room. Record your personal best peak flow number and peak flow zones in your asthma diary.
Fire fighting and asthma
Fire fighters are exposed to smoke and other toxicants as part of their job. Smoke contains particulates and gases that are irritating to the lungs and upper respiratory tract. These irritants are the products of combustion from both synthetic (plastics) as well as natural products (wood). Monitoring data indicates that fire fighters can be exposed to a whole host of respiratory toxicants including hydrogen chloride, phosgene, sulfur dioxide, aldehydes and particulates. Smoke-induced airway hyper-responsiveness can exacerbate the symptoms of wheezing in fire fighters with asthma.
What is COPD?
Chronic obstructive pulmonary disease (COPD), also called chronic obstructive lung disease, is a syndrome that includes both chronic bronchitis and emphysema. In most patients these two diseases occur together, although there may be more symptoms of one than the other. Most patients with these diseases have a long history of heavy cigarette smoking, or familial alpha 1 -antitrypsin deficiency. It is estimated that 80-90% of COPD cases are caused by cigarette smoking. However, there are also other causes of COPD. Exposure to coal mine dust, cotton dust, silica, and grain dust are known causes of occupational COPD.
Emphysema is irreversible lung damage that occurs when the walls between the lung’s air sacs lose their ability to stretch and recoil. They then become weakened and break. Elasticity of the lung tissue is lost, trapping air in the air sacs and limiting the ability exchange oxygen and carbon dioxide. When emphysema is the severe enough, the support structure of the airways is lost and obstruction of the airflow is evident. Symptoms can include cough, shortness of breath, and a limited exercise tolerance.
Smoking has been proven to cause and accelerate the decline in lung function in people with COPD. Air pollution has also been shown to be harmful to people with chronic lung disease, especially exposure to particulate air pollution (diesel exhaust). Air pollution can trigger asthmatic attacks or exacerbate COPD. Agents thought to be responsible for these harmful effects include nitrogen dioxide, sulfur dioxides, ozone, and particulates from fuel combustion and vehicles.
Are there medications for COPD?
Yes. Most people with asthma can be treated very successfully with inhalers (or puffers) or pills. Treatment plans will have to be worked out with your doctors. However, with COPD, most of the changes may be irreversible. Inhalers or pills can help with symptomatic relief but may not be able to reverse the damage that has already been done. Asthma and COPD do not go away by themselves. They require an understanding of the disease and monitoring of airway function (either through peak flow meters or spirometry).
Treatment for COPD
There is no specific treatment to cure or reverse the damage of COPD. The goal of COPD treatment is to provide relief of symptoms and prevent progression of the disease. A treatment regimen will include stop smoking, the use of bronchodilator drugs (inhalers or pills), antibiotics, and breathing exercise (pulmonary rehabilitation).
For severe COPD, your physician may recommend lung transplantation at a major medical center. Prevention of COPD is more important, as there is no treatment for end-stage COPD. Prevention strategies will include smoking cessation, avoidance of exposure to air pollution, use of SCBA for fire fighting, and maintaining good health to fight off respiratory tract infections.
Fire fighters and COPD
Fire fighters should undergo annual spirometry as part of an annual physical examination, as recommended by the IAFF/IAFC Fire Service Joint Labor Management Wellness Fitness Initiative. Early signs of decline in lung function and problems with airway diseases, such asthma or COPD, may be encountered as part of the medical surveillance programs. In many instances, especially with firefighters who smoke, symptoms and signs of COPD may be ignored by the patients until they develop irreversible damage.
Depending on when the diagnosis is made and how aggressively fire fighters can change exposures and behaviors, further decline in lung function can be slowed. The use of self-contained breathing apparatus (SCBA) by firefighters can also slowed down the progression by preventing inhalation of pulmonary irritants and reduce the risk of smoke inhalation injuries. However, smoking cessation is often the most important factor in preventing further decline of lung function.
Asthma and COPD are classified as Category B medical conditions under NFPA 1582, Standard on Medical Requirements for Firefighters. Category B conditions mean that the severity of the health condition is the determining factor in ones’ ability to function as a fire fighter. So, detecting and managing asthma and COPD before these diseases get to the point where they interfere with the ability to perform the duties of fire fighting is very important.
Self-contained breathing apparatus (SCBA) has dramatically reduced the incidence and severity of smoke inhalation injury among structural firefighters.
Figure 6 shows an example of a full SCBA suit.
Special circumstance: Wild land fire fighting
Wild land firefighters are not likely to experience the extreme acute exposure that structural fire fighters. However, they are still chronically exposed to multitudes of contaminants that are products of combustion of natural materials, including carbon monoxides, sulfur dioxides, particulate matter of variable composition, aldehydes, and polyaromatic hydrocarbons (PAHs). They may also be exposed to substances such as lead or herbicides that may have been deposited on foliage. Ground dust and naturally occurring silica or asbestos may also be a hazard. Coupled with the effects of those chemicals that were used as fire-retardant to fight fires, gasoline and other fuels used for intentional burning, the range of exposure of wild land firefighters may be more diverse.
Smoke inhalation can cause airway injury and caused an acute decline in pulmonary functions. Temporary increase in airway responsiveness has been reported in association with acute exposure to fire smoke. This is also true with structural fire fighting. Repeated exposures to smoke may contribute to an excess in annual decline in lung function compared to the normal population. In wild land fire fighting, exposures may be more centered across a fire season (typically May through November). Studies of wild land fire fighters noted significant cross-season increases in eye irritation and wheezing symptoms correlated with the fire fighting activities. Studies have also observed a decline in average FEV1 and FVC cross-seasonally.
Self-contained breathing apparatuses used by structural fire fighters have not been feasible in wild land fire environment. Existing air-purifying respirators have been recommended for exposure control in combination with continuous CO monitoring that can activate the alarm when a threshold level is exceeded.
General information of Asthma and COPD for the public and References:
10. Raven, PB., Davis TO., Shafer CL., Linnebur AC., 1977. Maximal stress test performance while wearing a self-contained breathing apparatus. J. Occup. Med. 19: 802-806.
11. Szeinuk J., Beckett, WS., Clark N., and Hailoo W. Medical Evaluation for Respirator Use. Am J of Ind Med 37; 142-157 (2000).