National Childhood Asthma Prevention Campaign
The Environmental Council of the States (ECOS)
National Childhood Asthma Prevention Campaign
Click here for A Report from the Working Group of Representatives from State Health and Environmental Agencies on Strategies to Reduce Environmental Factors that Contribute to Asthma in Children
Click here for the Toolbox of Resources for State Agencies
Click here for the ECOS Resolution on Reducing Environmental Factors that Affect Asthma in Children
Click here for a Matrix of State Programs related to asthma
The Environmental Council of the States (ECOS) is working with the Association of State and Territorial Health Officials (ASTHO) on a project related to the prevention and reduction of childhood asthma triggered or aggravated by indoor and outdoor environmental conditions. This project will build upon the work currently underway at ECOS and ASTHO, utilizing the childhood asthma information being collected through the Children's Environmental Health Profiles.
Over the course of several months, a workgroup developed a vision statement, goals and draft action agenda. The documents were proposed for discussion in a groundbreaking meeting that took place in San Diego, CA in August 2001, titled "Catching Your Breath: A conference for leaders of state environment and health agencies." Over a hundred representatives from thirty-nine States (fifty-two state environment and health departments), two federal agencies and nine other organizations participated in this meeting, the first that brought together state environment and health officials to discus children's asthma. The participants agreed on the proposed goals, vision statement and the topic areas for the action agenda, and urged for continuing collaboration among environment, health, education, housing and other relevant state departments.
At the 2001 Annual Meeting, ECOS passed a resolution endorsing the goals and vision statement. To further elaborate the action agenda, the state workgroup divided it into four workable sections with specific topics: asthma data, indoor environments, outdoor environments, and schools and child care settings. This gave the States an opportunity to discuss specific differences between health and environmental systems, something rated as highly important during the San Diego meeting. During 2002, the workgroup met five times to discuss the specific topics and then wrap-up the recommendations from each meeting into a single document.
The final Report from the Working Group of State Health and Environment Agencies - "CATCHING YOUR BREATH: Strategies to Reduce Environmental Factors that Contribute to Asthma in Children" has been released. The report contains a vision statement and action agenda developed by representatives from environmental and health agencies, and identifies steps states can take to address childhood asthma in homes, schools, childcare centers and outdoor environments. It is intended to serve as a blueprint for States and describe fruitful areas for action, and not to bind states to specific commitments. Some states may address some areas while other states emphasize others, based on distinct needs.
ECOS has sponsored five state pilots on childhood asthma in Wyoming, Wisconsin, and California (with funding from EPA Headquarters), as well as in Idaho and Oregon (with funding from EPA Region 10). To qualify for the grant awards, the applicants had to prove that the state environmental agency and the public health department would collaborate substantially toward the completion of the project. The pilots address various areas pertaining to childhood asthma, such as in-home exposures to environmental triggers of asthma, disseminating information regarding forecasts of unhealthy air quality, measuring PM outdoor air at schools and establishing associations with increased asthma exacerbations, reducing idling around schools, assembling data sets consisting of health, environmental, and housing information for use with spatial analytic tools to identify patterns or risk factors correlated with higher rates of asthma prevalence and morbidity. All pilots will be completed in 2004
Childhood Asthma Tool Box
Toolbox of Resources for State Health and Environment Agencies
State environmental agencies and state health agencies are working together to develop strategies to reduce childhood asthma. This site provides links to resources for states -- including both background information and examples of useful and informative tools, products, and initiatives. Short executive briefing materials are shown as "one-pagers."
The topics addressed at this site are:
What is asthma and why do kids get it?
American Lung Association.
Overview of Childhood Asthma
Short introduction to what asthma is, how it affects the lungs, how episodes are triggered
US Environmental Protection Agency Office of Children's Health Protection.
Asthma and Upper Respiratory Diseases
Discusses allergic and non-allergic triggers for asthma and possible environmental causes.
What triggers asthma attacks?
Asthma and Environmental Triggers (Connecticut Department of Public Health)
What is the monetary cost of asthma in children?
National Center for Education in Maternal and Child Health, Georgetown University. Lauren Raskin, (Feb. 2000)
Breathing Easy: Cost of Asthma http://www.ncemch.org/policy/asthma.html#The Cost of Asthma
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How many people have asthma in the US?
Nearly one in thirteen children in the US have asthma, and this percentage is growing more rapidly in preschool age children than in any other group. (2)
Is asthma increasing?
Asthma is increasing in the US and around the world. The National Heart, Lung, and Blood Institute reports that the prevalence of asthma around the world has doubled in the last 15 years (1). In the US, the Centers for Disease Control estimates that prevalence among persons up to 17 years old increased about 5% per year from 1980 to 1995. (4)
In the US, the rates of deaths from asthma, hospitalizations and visits to emergeny rooms have been increasing for more than 20 years, particularly among children and African Americans. Since 1979-1982, the death rate for blacks has increased 71% while for whites it increased 41% (1).
What kind of data do we have about how many people have asthma and whether this is increasing?
Data about asthma is more limited than data for many other important diseases.
It is difficult or impossible to estimate the annual incidence of asthma in the US. "Incidence" means the number of new cases diagnosed over the period of a year. Looking at the incidence of a disease is the best way to determine how the frequency of the disease changes over time.
Asthma is usually presented as "prevalence." This means the number of people who have the disease in a population at a particular point in time. Prevalence is a less informative way of looking at changes in the rate of disease because it depends on two factors -- how many people get the disease and how long they have the disease. It is harder to see changes in frequency when looking at prevalence numbers than when looking at incidence numbers.
What are the main data sources for asthma?
Data about asthma is usually one of these four sources:
Death certificate or vital statistics -- this source is useful for looking at he number of cases of asthma that were not managed successfully through medical care, but it is not a very good indicator of how the frequency of the disease is changing because most people do not die of asthma, and in many cases deaths represent a failure of care. Almost all states report mortality data, and there is a national data system for this information -- the National Vital Statistics System maintained by the National Center for Health Statistics.
The Healthy People 2010 project reports that the rate of asthma deaths in children are 2.1 per million for children under 5 and 3.3 per million for children from 5 to 14. The goal is to reduce these rates. (3)
Hospital discharges or hospitalization data -- this source provides information about the number of cases of asthma that were serious enough to require admission to a hospital. These cases represent serious cases of asthma. The frequency of hospital discharge or hospitalization is also influenced by access to care. Those without health insurance are less likely to be admitted to the hospital than others. Several states consider hospital discharge or hospitalization data.
The Healthy People 2010 project reports that the rate of asthma hospitalizations in children under 5 are 45.6 per 10,000 and 12.5 per 10,000 for children over 5 and adults. The goal is to reduce these rates. The national data system is the National Hosptial Dischrage Survey conducted by the National Center for Health Statistics. (3)
Emergency room visits for asthma -- this source provides information about the number of cases of asthma that required treatment at an emergency room. This represents serious cases of asthma in general. However, some uninsured people are likely to be treated in an emergency room who might have been admitted to a hospital if they had health insurance. Also, people who do not receive regular medical care and assistance to manage their asthma on a day to day basis are more likely than others with similar severity of asthma to end up in an emergency room. So, people without good access to medical care are likely to be over-represented in emergency room visit statistics.
For environmental studies, investigators generally view emergency room visits as the most sensitive indicator of adverse environmental conditions that contribute to disease on a daily basis. A few states consider emergency room visits data.
The Healthy People 2010 project reports that the rate of ER visits for children under 5 was 150 per 10,000 and 71.1 per 10,000 for children over 5 and adults. The goal is to reduce these rates. The national data source is the National Hospital Ambulatory Medical Care Survey conducted by the National Center for Health Statistics. (3)
Health Survey Data - Surveys of people to ask them about their health are conducted by agencies such as the National Center for Health Statistics.
The National Health Interview Survey asks questions about asthma. It is used as a source of national estimates of the prevalence of asthma. This survey does not break down data by state and does not interview enough people to allow for state level estimates.
The Behavioral Risk Factors Surveillance Survey (BRFSS) focuses largely on asking people about their own actions that may affect their health. It asks questions about how much people smoke and how much they exercise, for example. The survey is conducted at the state level and produces information for individual states. A module of questions about asthma have been developed for this survey, and some states have reported that they will be including these questions in future surveys.
School surveys - School districts in some states collect some information about asthma. There does not appear to be a standard format for this data. It appears that schools in some states may report asthma cases that are treated by school nurses and other states may survey students or parents about asthma and report something more like prevalence estimates.
Health care utilization data - Data provided through the health care system can be used to estimate asthma incidence or prevalence, as well as severity. This requires that all medical treatment information for a defined population be available in a standard format. This is the case for populations who have government health services, such as those who receive Medicaid. The records of health care for Medicaid-eligible persons can be used to estimate asthma. Several states look at this type of data. Information from health insurance services made available to children outside Medicaid might also be possible to use for this purpose.
What are the priorities for tracking of asthma?
Several studies that have considered how to improve the current system suggest that a national system would be a priority. At present, different states look at different kinds of data. It does not appear that state efforts are converging toward any particular approach to improving data collection and tracking.
Health Track, a project of the Pew Trusts, recommended a national tracking system for asthma, as have several other strategy documents.
1. National Institutes of Health. National Heart, Lung, and Blood Insitute. 2001. Data release for World Asthma Day, May 2001.
2. President's Task Force on Environmental Health Risks and Safety Risks to Children. Asthma and the Environment: A Strategy to Protect Children. Revised May 2000.
3. US Department of Health and Human Services. Tracking Healthy People 2010. Section 24 - Respiratory Diseases. November 2000. http://www.cdc.gov/nchs/hphome.htm.
4. CDC. Measuring childhood asthma prevalence before and after the 1997 redesign of the National Health Interview Survey -- United States. Mortality and Morbidity Weekly Report. 49(40): 908-911. October 13, 2000. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm4940a2.htm
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What strategies have been developed to address asthma at the international level?
The World Health Organization works with health authorities around the world to improve management of asthma in children and to prevent attacks. The most recent strategy document from WHO was issued in 1999 and addresses a wide array of topics. (1) This strategy focused primarily on research needs but also recommended that environmental tobacco smoke be avoided; that children with asthma avoid dust mite and animal dander; that patient education programs be used to increase knowledge about asthma and management.
What strategies have been developed to address asthma in the US?
The federal agencies worked on a strategy to address environmental factors that contribute to asthma, issued in 2000. (2) Key recommendations include:
>> more research to find environmental factors that contribute to onset of asthma and to develop strategies to improve quality of life for people with asthma; >> expanded state and local public health action towards education, tracking of disease, and coalitions for prevention; >> reduction of children's exposures to asthma triggers such as environmental tobacco smoke in their homes; >> continued reductions in outdoor air pollution; >> establishing school-based programs to reduce triggers in schools and assist children to manage asthma and participate in activities; >> to reduce disparate impact of asthma on children of color and improve asthma management for children within the Medicaid program.
The strategy included, as guiding principles, a commitment to focus on disproportionate impacts of asthma on children of color and those living in poverty and emphasis on partnerships and community-based programs
What kind of strategies have been proposed for the Catching Your Breath Conference?
The focus of the conference is to look at strategies for how state health authorities and state environmental authorities can work together toward prevention of asthma attacks.
The focus of this conference is complementary to work to improve medical management and treatment of asthma and the sponsoring organizations stand in support of these efforts.
A steering committee of state agency representatives have worked with staff from the Environmental Council of the States (ECOS), the Association of State and Territorial Health Officials (ASTHO), and the US Environmental Protection Agency, and with a contractor to analyze what states are doing now to address asthma in children and to identify possible opportunities for integration of health and environment efforts.
One of the purposes of the conference is to work on the vision statement and action agenda.
What will happen after the meeting?
The work completed at the Catching Your Breath conference will be sent back to ECOS and ASTHO for further review and consideration, through the normal process of these organizations.
1. World Health Organization. Prevention and Allergy and Asthma Interim Report. Based on WHO Meeting on the Primary Prevention of Asthma. 5-6 December 1999, Geneva. Management of Noncommunicable Diseases Department, Chronic Respiratory Diseases and Arthritis. 1999. http://www.ginasthma.com/
2. President's Task Force on Environmental Health Risks and Safety Risks to Children. Asthma and the Environment: A Strategy to Protect Children. Revised May 2000.
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Coalitions to Address Asthma
Resources for state health and environment agencies working together to reduce asthma in children. Sponsored by ECOS
Resources for developing coalitions http://www.nhlbisupport.com/asthma/coalitioncorner/
Network of asthma coalitions http://www.nhlbisupport.com/asthma/coalitioncorner/roster.htm
Projects Funded to work on disparities in asthma http://hin.nhlbi.nih.gov/ast_maps/awardee.html
Links to State and Regional Coalitions
Arizona -- DC-ALA -- Chicago Asthma Consortium -- Chicago Asthma Blueprint in PDF format -- Idaho -- Mid-Atlantic Regional Initiative -- Michigan Coalitions-ALA -- Minnesota-ALA -- Oregon Asthma Network -- San Francisco Bay Area -- Texas Gulf Coast Asthma Coalition -- Dallas Asthma Coalition -- Washington State Asthma Coalition-ALA
Allies Against Asthma is a program funded by the Robert Wood Johnson Foundation to develop coalitions bringing together clinical and public health approaches to asthma. The principal focus is on improving management of asthma for individual patients. Eight communities received awards for planning projects. The project also includes a component for environmental and health policy initiatives. http://www.rwjf.org/app/rw_about_our_grantees/rw_gra_npo_detail.jsp?id=ZAP
The University of Michigan sponsors a web site that explains the project at http://www.asthma.umich.edu/
The University of Kansas sponsors a web site of tools for community coalition building at http://ctb.ukans.edu/services/AlliesAgainstAsthma/
This site has pages for capacity-building that include resources for developing leadership, assessing communities needs, and developing cultural competence and a troubleshooting guide for community oriented processes. Review the policies for use of these materials before using; most uses for non-profit purposes are authorized.
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Education Programs to Address Asthma and Triggers
National Asthma Education Program sponsored by the National Heart Lung and Blood Institute. Started in 1989 to improve the response to asthma. Focus is on effective control of asthma. Sponsors coalitions to pull together partners to help children and others with asthma. All major medical groups, public health groups, and agencies belong to this initiative. http://www.nhlbisupport.com
University of Montana
Instructional module on asthma. Extensive resources including transparencies and script for an educational program. http://www.montana.edu:80/wwwcxair/asthma.htm
Resources for educators on indoor air quality. Extensive resources. http://www.montana.edu:80/wwwcxair/train.htm
Indoor air quality home tour. Designed for homeowners. How to identify and solve indoor air quality problems. http://www.montana.edu:80/wwwcxair/home_tour.htm
Training manual: Healthy Indoor Air in America's Homes. Manual prepared by Extension. Portions are available on-line. Paper copy with accompanying materials can be ordered at this site. http://www.montana.edu:80/wwwcxair/notebook.html
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What is the role of schools in addressing asthma?
Schools can play several roles in addressing asthma.
First, children spend a significant amount of time at schools. Air quality and the presence of triggers in schools can affect the experience of asthma. Often because of deferred or inadequate maintenance, school buildings may be poor environments for children. One aspect of addressing asthma is to address the quality of the indoor environment in schools.
Second, schools can be a place where children with asthma experience asthma attacks. The response of school personnel to such attacks can make a big difference, and even be a matter of life and death. Proper training of school personnel, particularly school nurses, to respond to asthma is critical. Schools need to be fully integrated into the action plan to manage asthma for children.
Third, schools can be a source of education for both children and parents about asthma. School nurses may identify children who exhibit asthma symptoms and have not been diagnosed. Nurses and teachers may offer information to individuals or in a group situation about asthma and ways to control it.
Fourth, schools can help children manage their asthma so that they can take part in outdoor and sports activities. Specific resources are available to help school nurses and others with this.
What is the role of child care facilities?
Child care facilities can have certain aspects of homes, such as the presence of soft toys and other items that require special action to control asthma triggers. Resources are available to help parents evaluate child care facilities and to help the facilities address asthma.
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Indoor Environmental Triggers
What does "trigger" refer to?
The term "trigger" refers to something that contributes to an asthma attack in a person who already has asthma.
What are the principal indoor factors that affect asthma?
While there is no clear consensus about what causes asthma to develop in the first place, there is general agreement that certain triggers contribute to asthma stacks. Sometimes this is called exacerbation of asthma.
In the indoor environment, the following are generally recognized to be triggers of asthma attacks (1):
Environmental tobacco smoke (second-hand smoke) -- especially in young children (2)
Allergens produced by dust mites (2, 3)
Molds, fungus, dampness (4)
Allergens produced by cockroaches (5) (6)
Allergens produced by household pets, especially cats (7)
Nitrogen dioxide (NO2)
Not all asthmatics respond to all of these triggers.
What can be done to reduce the impact of these factors on children with asthma?
Many or all of these factors can be reduced or controlled, and this can improve the experience of people with asthma by reducing the frequency of attacks and/or need for medication or medical assistance (8, 9).
Home, school, and day care environments are all relevant targets for intervention efforts to reduce indoor factors.
The strategies that would be effective vary.
For environmental tobacco smoke, changes in individual behavior will obviously reduce the trigger in the home. Such changes are difficult to achieve.
For factors related to dampness, including molds and fungus, as well as cockroaches, repair or alternations to buildings may be needed to prevent the intrusion of water or insects, to improve ventilation, or to remove contaminated materials. These changes can require financial resources that may be beyond the means of many families, particularly low income families most likely to live in poor quality housing (10). Those most likely to be most in need of building alterations are least likely to be able to afford to pay for them or to need assistance in compelling landlords to do so. Participation by housing authorities and availability of funding to provide for repairs may be needed to solve these building factors.
Nitrogen dioxide usually originates indoors from poorly vented cooking or heating. Combustion fumes are associated with exacerbation of asthma (11). Reducing these exposures can require installation of ventilation to reduce indoor concentrations, which can cause a variety of health effects in addition to asthma.
Dust mites and pet allergens can be controlled through household practices including removal of materials that harbor the allergens, regular cleaning and washing of bedding materials, and covering mattresses and pillows in mite-proof covers (12, 13). Bare floors rather than carpets are recommended, though even this practice does not eliminate high dust mite levels in all cases (14). Reduction of humidity can reduce levels of dust mite allergen (15). Education of families can contribute to these practices.
To address indoor factors effectively requires participation of several sectors: health, housing, education, and environment (16).
Schools and day care facilities can also take steps to reduce triggers in their buildings.
1. Institute of Medicine. Clearing the Air: Asthma and Indoor Air Exposures. Washington, DC: National Academy Press, 2000.
2. Gold DR. Environmental tobacco smoke, indoor allergens, and childhood asthma. Environmental Health Perspectives 2000; 108 Suppl 4:643-51.
3. Sporik R, Platts-Mills TA, Cogswell JJ. Exposure to house dust mite allergen of children admitted to hospital with asthma. Clinical and Experimental Allergy 1993; 23:740-6.
4. Nicolai T, Illi S, von Mutius E. Effect of dampness at home in childhood on bronchial hyperreactivity in adolescence. Thorax 1998; 53:1035-40.
5. Potera C. Working the bugs out of asthma. Environmental Health Perspectives 1997; 105:1192-4.
6. Rosenstreich DL, Eggleston P, Kattan M, Baker D, Slavin RG, Gergen P, Mitchell H, McNiff-Mortimer K, Lynn H, Ownby D, Malveaux F. The role of cockroach allergy and exposure to cockroach allergen in causing morbidity among inner-city children with asthma. New England Journal of Medicine 1997; 336:1356-63.
7. Nelson HS, Szefler SJ, Jacobs J, Huss K, Shapiro G, Sternberg AL. The relationships among environmental allergen sensitization, allergen exposure, pulmonary function, and bronchial hyperresponsiveness in the Childhood Asthma Management Program. Journal of Allergy and Clinical Immunology 1999; 104:775-85.
8. Shapiro GG, Wighton TG, Chinn T, Zuckrman J, Eliassen AH, Picciano JF, Platts-Mills TA. House dust mite avoidance for children with asthma in homes of low-income families. Journal of Allergy and Clinical Immunology 1999; 103:1069-74.
9. Carswell F, Oliver J, Weeks J. Do mite avoidance measures affect mite and cat airborne allergens? Clinical and Experimental Allergy 1999; 29:193-200.
10. Kuster PA. Reducing risk of house dust mite and cockroach allergen exposure in inner-city children with asthma. Pediatric Nursing 1996; 22:297-303.
11. Ostro BD, Lipsett MJ, Mann JK, Wiener MB, Selner J. Indoor air pollution and asthma. Results from a panel study. American Journal of Respiratory and Critical Care Medicine 1994; 149:1400-6.
12. Vanlaar CH, Peat JK, Marks GB, Rimmer J, Tovey ER. Domestic control of house dust mite allergen in children's beds. Journal of Allergy and Clinical Immunology 2000; 105:1130-3.
13. Bahir A, Goldberg A, Mekori YA, Confino-Cohen R, Morag H, Rosen Y, Monakir D, Rigler S, Cohen AH, Horev Z, Noviski N, Mandelberg A. Continuous avoidance measures with or without acaricide in dust mite-allergic asthmatic children. Annals of Allergy, Asthma, and Immunology 1997; 78:506-12.
14. Chew GL, Burge HA, Dockery DW, Muilenberg ML, Weiss ST, Gold DR. Limitations of a home characteristics questionnaire as a predictor of indoor allergen levels. American Journal of Respiratory and Critical Care Medicine 1998; 157:1536-41.
15. Warner JA, Frederick JM, Bryant TN, Weich C, Raw GJ, Hunter C, Stephen FR, McIntyre DA, Warner JO. Mechanical ventilation and high-efficiency vacuum cleaning: A combined strategy of mite and mite allergen reduction in the control of mite-sensitive asthma. Journal of Allergy and Clinical Immunology 2000; 105:75-82.
16. Kattan M, Mitchell H, Eggleston P, Gergen P, Crain E, Redline S, Weiss K, Evans R, 3rd, Kaslow R, Kercsmar C, Leickly F, Malveaux F, Wedner HJ. Characteristics of inner-city children with asthma: the National Cooperative Inner-City Asthma Study. Pediatric Pulmonol 1997; 24:253-62.
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Outdoor Environmental Factors
What are the principal outdoor factors that affect asthma?
Certain outdoor environmental factors are thought to contribute to making asthma worse in people who already have the disease. Sometimes this is called exacerbation of asthma. The term "trigger" refers to something that contributes to an asthma attack in a person who already has asthma. Not all asthmatics respond to all triggers.
In the outdoor environment, both air pollutants (1) and biological allergens (pollens, fungus, molds) can make asthma worse. Pollutants include ozone, particulate matter, sulfur dioxide, carbon monoxide, and nitrogen dioxide. In addition, the World Health Organization identified traffic pollution as a causative influence for asthma (2), and diesel exhaust has also been identified as a possible concern (1, 3).
Biological allergens include pollens, molds, and fungi (4). Weather conditions including thunderstorms may particularly affect asthmatics (5, 6).
It is less certain what causes the onset of asthma in the first place. There is some evidence that exposure to ozone and biological allergens (particularly certain types of pollens) may contribute to the initial development of asthma, but there is no consensus in the scientific community about this. Environmental factors may contribute to the onset of asthma, probably in conjunction with other factors including genetic factors.
What Air Pollutants Are Thought to Exacerbate Asthma?
Many studies have reported that higher concentrations of air pollution are associated with higher frequency of asthma reported several ways -- as emergency room visits (7), hospitalizations or hospital discharges, use of medication, increased frequency of symptoms, increased visits to doctors' offices, or increased number of days of school or work missed. Decreased lung function is also reported in some studies.
The results of the studies are not completely consistent, in that not all studies find that the same pollutants are associated with the same effects. Some studies find effects of particulate matter; while other find effects of ozone. Moreover, some studies find no effect. Below, only positive studies are cited.
Particles in the air are often referred to as particulate matter or as total suspended particulates. Different studies measure studies of different sizes. "PM 10" refers to particles 10 microns or less in diameter, while "PM 2.5" refers to particles 2.5 microns or less.
Times Series Studies -- Many studies have reported higher frequency of asthma on or shortly after days when particulate matter in the air is high, including increased emergency room visits for adults in Seattle (8, 9) and California (10) and for children (11-13);
Panel Studies -- Studies that follow groups of people over time have reported increased symptoms or severity of asthma to be associated with higher exposures to particulate matter in adults (14), African-American children in Los Angeles (15), children in Southern California (16), fifth and sixth grade students in Utah (17), children in Vancouver (18), children in Seattle (19), and children in Mexico City (20). Some studies have found reduced lung function in children (20, 21) and in children over 15 (22), and particular susceptibility for asthmatic children (18).
Long-term Studies -- A few studies have reported an association between long-term exposures to PM 2.5 and increased severity or symptoms of asthma in adults (23) and in children (24).
Ozone is a gas that is formed from chemical reactions in the lower atmosphere in the presence of light. It is the pollutant most associated with "smog." Ozone at ground level causes adverse health effects, while ozone in the upper atmosphere protects the earth from radiation from the sun.
Times series studies -- Many studies have reported higher frequency of asthma on or shortly after days when ozone concentrations in the air are high, including increased emergency room visits for adults in Seattle (9) and for children (13, 25, 26) ; increased medication use for more severely asthmatic children (15); and increased visits to doctors' offices (27) .
Panel studies -- have reported higher exposures of ozone to be associated with diminished lung function in children over 15 (22) and increased severity of asthma symptoms for children in the US (16, 28), African-American children in Atlanta (29), children in Australia (30), and children in Mexico City (20). Effects in older children in San Diego were seen particularly when personal exposure to ozone was measured (21, 31). Asthmatics may be considered a susceptible population for effects of ozone (32)
Sulfur dioxide is a gaseous pollutant for which the primary sources are related to combustion.
On or shortly after days when particulate matter in the air was high, studies reported increased emergency room visits (11) ; and increased visits to doctors' offices (27) for asthma.
On or shortly after days when nitrogen dioxide in the air is high, studies have reported increased hospitalization or hospital discharges (33) and increased symptoms in African-American children (15). Some studies have looked at lung function and found that reduced lung function is associated with exposures to higher concentrations of particulate matter. Studies looking at long-term exposures to nitrogen dioxide have reported an association with increased severity or symptoms of asthma in adults (23) and children (24).
On or shortly after days when carbon monoxide in the air is high, studies have reported increased emergency room visits for adults (9) and children (12) and increased asthma symptoms in children (19). A study of long-term exposures reported an association with increased severity of asthma (23).
What Biological Allergens Exacerbate Asthma?
The outdoor biological allergens that are thought to exacerbate asthma are pollens, molds, and fungus
Pollens are released by plants and vary geographically according to the type of vegetation. Pollens are typically monitored by capture in traps placed on roofs, then identification and counting of pollen particles under a microscope (34). Improvements in both collection methods to collect a higher percentage of particles and of identification and counting methods, to better ascertain the amount of allergen contained in the sample, would improve the value of monitoring for prediction of impacts on asthmatics (34). Studies of the relationship between pollen exposures and asthma generally look at either the relationship between sensitization as determined by a skin test and the presence of asthma or exposure to pollen and asthma symptoms (34). The pollens typically identified may not represent those most important to exacerbation of asthma (35)
Higher exposure to certain molds (Alternaria and Cladosporium) was associated with increased symptoms in a panel of African-American children in Los Angeles (15)
A large study of outdoor concentrations of pollens and fungus, as well as air pollutants, found that emergency room visits were associated with higher concentrations of certain kinds of fungus but not pollens (36). A panel study of a few children found that higher concentrations of fungus, but not pollens, were associated with increases severity of symptoms in asthmatic children (4, 31), increased use of medication (4), and reduced lung function (4)
There is some evidence that the combination of air pollutants and bio allergens may interact to increase the effect on asthmatics. One study reported that exposure to pollens and air pollutants led to heightened response for ozone but not nitrogen dioxide (37).
1. D'Amato G, Liccardi G, D'Amato M. Environmental risk factors (outdoor air pollution and climatic changes) and increased trend of respiratory allergy. Journal of Investigational Allergology and Clinical Immunology 2000; 10:123-8.
2. WHO. WHO Prevention of Allergy and Asthma Interim Report. Geneva: World Health Organization, Management of Noncommunicable Diseases Department, Chronic Respiratory Diseases and Arthritis, 2000.
3. Nel AE, Diaz-Sanchez D, Li N. The role of particulate pollutants in pulmonary inflammation and asthma: evidence for the involvement of organic chemicals and oxidative stress. Current Opinion in Pulmonary Medicine 2001; 7:20-6.
4. Delfino RJ, Zeiger RS, Seltzer JM, Street DH, Matteucci RM, Anderson PR, Koutrakis P. The effect of outdoor fungal spore concentrations on daily asthma severity. Environmental Health Perspectives 1997; 105:622-35.
5. Girgis ST, Marks GB, Downs SH, Kolbe A, Car GN, Paton R. Thunderstorm-associated asthma in an inland town in southeastern Australia. Who is at risk? European Respiratory Journal 2000; 16:3-8.
6. Lewis SA, Corden JM, Forster GE, Newlands M. Combined effects of aerobiological pollutants, chemical pollutants and meteorological conditions on asthma admissions and A & E attendances in Derbyshire UK, 1993-96. Clinical and Experimental Allergy 2000; 30:1724-32.
7. Goldsmith JR, Friger MD, Abramson M. Associations between health and air pollution in time-series analyses. Arch Environ Health 1996; 51:359-67.
8. Schwartz J, Slater D, Larson TV, Pierson WE, Koenig JQ. Particulate air pollution and hospital emergency room visits for asthma in Seattle. American Review of Respiratory Disease 1993; 147:826-31.
9. Sheppard L, Levy D, Norris G, Larson TV, Koenig JQ. Effects of ambient air pollution on nonelderly asthma hospital admissions in Seattle, Washington, 1987-1994 [see comments]. Epidemiology 1999; 10:23-30.
10. Lipsett M, Hurley S, Ostro B. Air pollution and emergency room visits for asthma in Santa Clara County, California. Environmental Health Perspectives 1997; 105:216-22.
11. Chew FT, Goh DY, Ooi BC, Saharom R, Hui JK, Lee BW. Association of ambient air-pollution levels with acute asthma exacerbation among children in Singapore. Allergy 1999; 54:320-9.
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