Environmental Exposures Linked to Worsening Asthma

The environment plays an important role in the severity and onset of asthma. Both indoors and outdoors, certain chemicals and biological agents (such as mold) in the air increase the risk of having an asthma attack. Some of these contaminants may actually cause asthma to develop.

Environmental tobacco smoke (ETS), or second hand smoke, has a major impact on asthma symptoms and asthma development. ETS brings on asthma attacks and makes a person with asthma more sensitive to other asthma triggers. In addition, ETS may actually cause the development of asthma in younger children.1, 2, 3, 4 Adding to this danger is the fact that the risk of developing asthma is greatly increased in children whose mothers smoke during pregnancy.5 This is particularly alarming since children are unable to avoid exposure to cigarette smoke from adults smoking in their homes or in cars where they are passengers.

Indoors, allergens produced by house dust mites, cockroaches, mold and pets trigger wheezing and other symptoms of asthma in those allergic to them. 6, 7, 8 House dust mites also cause the development of asthma and there is some evidence that cockroaches may as well.9 Some of these allergens are very common. For example, dust mites are found wherever common house dust is found, including bedding, upholstered furniture and carpeting. These allergens are often not only in homes, but schools as well, making it extremely difficult for children to avoid exposure.

People with asthma are also particularly sensitive to outdoor air pollution.10 Many common air pollutants, such as ozone, sulfur dioxide, and particulate matter (fine dust in air), irritate breathing passages and make asthma worse.11, 12 Indeed, ozone, an air pollutant, has been associated with the development of asthma in children who participate in outdoor sports.13 In addition, exposure to ozone or to particulate matter from diesel exhaust multiplies the impact of allergies on asthma.14, 15, 16 Diesel fuels more than 99% of US school buses, which transport 24 million students to school each day. Fine particulate concentrations on school buses have been found to be as much as 5-10 times higher than outdoor levels.17

Controlling Exposures Necessary for Reducing Asthma

The symptoms of asthma - wheezing, cough, and shortness of breath – can be greatly reduced by controlling environmental exposures. In several cases - environmental tobacco smoke, dust mites, cockroaches, and ozone exposure during exercise – steps to prevent exposure may even prevent asthma from developing.

Indoor exposure to allergens and pets has been linked to over 40% of the 4.6 million cases of doctor-diagnosed asthma among children and adolescents. If the cause of asthma in these cases is indeed these allergens, 2 million cases of asthma could be prevented – and $405 million saved annually - by eliminating exposure to cat, dust mite, cockroach and a common fungus called Alternaria. 18, 19

According to a 2003 report in the American Journal of Industrial Medicine Report, 23% of adult asthma can be attributed to workplace
exposures, especially in the cleaning, farming and transportation industries. Dr. Thomas H. Gassert from the Harvard School of Public Health published a study of workers diagnosed with occupational asthma in 1998.  He and his team of researchers conclude that the prevalence of asthma is "...unfortunate because occupational asthma is a preventable disease that often becomes chronic and may disable millions of people worldwide at considerable personal and social cost". They call for greater prevention efforts and quicker diagnosis and treatment by healthcare professionals.20  

Changes in housing maintenance and construction practices can greatly reduce asthma triggers by eliminating the conditions where allergens can get indoors, collect and/or grow. Practices such as those detailed in Healthy and Affordable Housing: Practical Recommendations for Building, Renovating, and Maintaining Housing: Before You Design, Build or Renovate 21 focus on dust and moisture control, ventilation, and integrated pest management. These aim to create healthier indoor environments in general, producing benefits for other environmentally related illnesses such as childhood lead poisoning as well as asthma.

In addition to building changes, families can make changes to further reduce exposure to dust and other indoor allergens. For example, use of special covers for pillows and mattresses and washing all bedding in hot water weekly can reduce asthma symptoms of children with mite allergen.22While steps like special cleaning may be effective, the time and money involved adds a burden to families, particularly those struggling with poverty or other stresses. The challenge remains to find effective ways to remove these very common allergens in ways that are reasonable for affected families.23

Outdoors, local, regional and national efforts are necessary to address the many varied and geographically diverse sources of pollutants that worsen asthma for millions of Americans. Despite the size and complexity of the problem of outdoor asthma triggers, parents and communities do have an opportunity to make a drastic change in children’s asthma by addressing diesel emissions, particularly from school buses. Exposures can be immediately reduced by controls on idling times and locations and limits on the amount of time students spend on buses.24Switching to natural gas school buses or retrofitting buses with emissions control technology in combination with use of ultra low sulfur fuels could have a powerful impact on air quality, reducing particulate as much as 83 – 93%.25The strong connection between the respiratory health of children and diesel emissions supports aggressive moves to new cleaner buses and cleaner fuels.

Web Resources

• A Study Links Trucks' Exhaust to Bronx Schoolchildren's Asthma

An article found in the NY Times, October 2006

• Asthma and Outdoor Air Pollution:  EPA Conference
  

• The Asthma and Environment Connection Bibliography (downloadable PDF document)

• The Asthma Epidemic

Abstract from The New England of Medicine

• About Children's Environmental Health
  http://www.cehn.org/cehn/Aboutceh.html
  
• America's Children and the Environment
  http://www.epa.gov/envirohealth/children
  
• Children's Health and the Environment: Resources for State Policy Makers

http://www.ncsl.org/programs/environ/envHealth/CHILDH.htm

• Current Air Quality Index

http://cfpub.epa.gov/airnow/

• Dampness/Mold has Significant Connection to Asthma

• U.S. Environmental Protection Agency, “Asthma Facts”
  http://www.epa.gov/asthma/about.html
  
• U.S. Environmental Protection Agency New England Region 1, “A Healthy Environment for our Future”
  http://www.epa.gov/region01/children/index.html
  
• Institute of Medicine's Report on Indoor Air Exposures and Asthma
  
• National Library of Medicine's community toxics site
  http://toxtown.nlm.nih.gov/
  
• Limiting Environmental Hazards and Pediatric Asthma Triggers
  http://www.childrenshealth.gov/topics/limiting_hazards.html
  
• National Institute of Environmental Health Sciences Asthma and Environment Studies

http://www.niehs.nih.gov/airborne/research/background.html

http://ehis.niehs.nih.gov/docs/2004/112-1/EHP112pa28PDF.PDF

Special Reports

• http://www.epa.gov/hhrp/files/CEH_Report_508.pdf
• The Health Effects of Wood Smoke by Environment and Human Health, Inc.

http://www.ehhi.org/woodsmoke/health_effects.html

• Risks to Asthma Posed by Indoor Health Care Environments

• Our Health and the Environment

• Surgeon General's Report on Secondhand Smoke (2006)
  http://www.surgeongeneral.gov/library/secondhandsmoke

• Indoor Air Pollution and California Policy Report

http://www.arb.ca.gov/research/indoor/ab1173/ab1173.htm

• Pollution and Children's Health -- AAHP

http://pediatrics.aappublications.org/cgi/reprint/114/6/1699.pdf

• ECOS/ASTHO Report on Strategies to Reduce Environmental Factors That Contribute to Asthma in Children
  http://ecosstage.forumone.com/files/868_file_1ASTHMAREPORTFINALDRAFT.pdf

• Short of Breath: Our Lack of Response to the Growing Asthma Epidemic and the Need for Nationwide Tracking Trust for America's Health, July 2001
  http://healthyamericans.org/topics/index.php?TopicID=4

Suggested Reading

1. Agency for Toxic Substances and Disease Registry (ATSDR).  Healthy Children-toxic environments.  Report of the Child Health Workgroup. Atlanta: USDHHS; 1997.
2. Amler RW, Smith L, editors.  Achievements in children's environmental health.  Atlanta: USDHHS, ATSDR, 2001
3. Bearer CF, "Environmental health hazards: how children are different from adults."  Future Child 1995;5(2):11-26.

5. Environmental Defense Fund. "Childhood Asthma and Poor Air Quality During Summer Months."

click here to see the Report

click here to see the Press Release

5. Etzel, RA, "How Environmental Exposures Influence the Development and Exacerbation of Asthma." Pediatrics: 2003, 112: 233-239.
6. Landrigan PJ, Carlson JE: "Environmental policy and children's health."  Future Child  1995;5(2):34-52.

7. New England Journal of Medicine, "The Effect of Air Pollution on Lung Development from 10 to 18 Years of Age". Volume 351:1057-1067, September 2004.