Environmental Triggers of Asthma Gaynor Govias BSc BEd CAI
Environmental Triggers of Asthma Third Edition Gaynor Govias, B. Sc., B. Ed., CAI
Gaynor D. Govias Environmental Triggers of Asthma Third edition 2014 The Asthma Education Clinic Ltd. All rights reserved. No portion of this book may be reproduced or transmitted in any form or by any means without the written permission of the publisher first being obtained. Cover artwork 2005 Aim Creations. Used with permission. The Asthma Education Clinic Ltd. 1328, 5328 Calgary Trail Edmonton, Alberta T6H 4J8 Canada www.asthmaed.com ISBN 1-896291-58-9
Contents Foreword 1 Air Pollution 3 Airborne pollution 3 Air pollution and asthma 5 The Great Outdoors 6 Pollens 6 Molds 6 Weather 7 Smog 7 Cold air 7 Indoor Allergens 7 Pets 8 Mold 8 House dust 8 Cockroach 9 Rodents 10 Latex 10 Volatile Organic Compounds 11 Formaldehyde 13 Environmental tobacco smoke 13 Indoor Contaminants 15 Bioaerosols 15 Improving Air Quality 16 Abbreviations 17 References 18
Environmental Triggers of Asthma Foreword The Guidelines for the Treatment of Asthma all place emphasis on control of the environment. This is the first step in managing asthma, and it should be done even before medication is prescribed. The triggers for asthma exacerbations lie in each individual s environment, and hence reduction in exposure and elimination of triggers (where possible) is a high priority. Some triggers are obvious, but individuals with asthma nonetheless have to be detectives to discover all the triggers in their environment (home, school and/or work) that are the cause of their asthma exacerbations. This is not an easy task the biphasic nature of asthma means that symptoms can occur both immediately (and then disappear with or without medication), or can also occur or re-appear several hours later with greater intensity. A Patient Diary in which patients keep brief notes about their daily activities, the foods they eat, the places they visit, and the possibly new things they have done each day can be very helpful. It can help patients determine their triggers, and it can help the health professional. The health professional can also help patients by taking a careful history, pointing out some of the more common triggers, and assuring the individual that environmental control is essential to managing asthma. This reference booklet discusses the most common environmental triggers of asthma. The asthma educator should however remember that new pollutants from new industrial processes are being added to our environment regularly, and that even seemingly innocent environments such as a lovely house that was unknowingly built over a toxic dump can harbour triggers.
Environmental Triggers of Asthma 3 Air Pollution Air pollution has serious health consequences. According to the World Health Organization, at least 2.4 million people die each year from causes directly related to such pollution. Of these deaths, 1.5 million are attributed to indoor air pollution. Health Canada s pyramid showing the effects of air pollution on the general population are shown in Figure 1. Effects of Air Pollution Mortality Hospital admissions Emergency Room Visits Physician Office Visits Reduced Physical Performance Medication Use Symptoms Impaired Pulmonary Function Subclinical Effects Percentage of Population Affected Severity of Effect Figure 1: Health Canada pyramid showing effects of air pollution The relation of air pollution to asthma is complex and confusing. There are clear indicators that an increase in pollution affects asthma. 1,2 Air pollution results in: decreased pulmonary function increased bronchial hyperresponsiveness (BHR) increased use of medication increased symptoms inflammatory and immune system changes increased emergency room visits increased hospital admissions and altered allergen response. 1,3 The confusion with regard to air pollution is that it does not seem to cause asthma. A series of studies in unified Germany has helped in studies of asthma and pollution. The old West Germany was very similar to North America in many respects, including affluence and a strong environmental lobby. In the old (Communist) East Germany there were many heavy industries and private homes burning solid fuel. These contributed to pollution of both the indoor and the outdoor environment. Both countries (East and West Germany) had a similar ethnic mix. In East Germany, non-specific symptoms (cough and bronchitis) were common. However, asthma incidence was higher in the less polluted, more affluent, West Germany. Studies 4,5 have shown that environmental control leads to a reduction in allergen exposure which results in reduced symptoms, reduced medication usage and reduced bronchial hyperresponsiveness. The environment can be categorized into two zones that of the outdoor and that of the indoor environment. It is obvious that the two are not independent of each other, that each affects and influences the other and much of what is said pertaining to the outdoor environment applies perhaps in an even more concentrated form to the indoor environment. Airborne pollution Air is comprised of many gases including oxygen and nitrogen, as well as biological particles such as dust, pollen, mold, spores, fungi, etc. Air pollution refers to the ozone, acidic and particulate matter content of air. Polluted air encourages photochemical reactions to take place so that nitrogen oxides, organic vapours, hydrocarbons, radiation and other reagents interact to produce ozone. 3 Thus polluted air is a combination of ozone, nitric oxide, nitric dioxide, sulphur dioxide, acid aerosols and particulate matter. Each causes its own problems. Ozone Ozone is considered a secondary component of air pollution. It develops over a period of time through the interaction between hot weather and pollutants from vehicle emissions. Being a gas, it moves easily with the wind; as a result, high ozone levels can be found not only within the source cities where it is created, but also in rural areas downwind of those cities. At low concentrations, ozone causes irritation of the eyes, nose and throat; headaches; nausea; and coughing. At higher concentrations it has been known to impair lung function 6,7 by reducing forced vital capacity (FVC), forced expiratory volume in one second (FEV 1 ) and peak expiratory flow rate (PEFR). It also results in altered macrophage activity and immune function that could reduce resistance to infection. 8 Ozone causes an early inflammatory response and cell recruitment 2,3, increasing inflammatory agents such as neutrophils, prostaglandin E 2 and F 2, and thromboxane B 2. As a potent oxidant that is insoluble in water, it is deposited all the way down into the peripheral airways.