Skip Navigation

Your Environment. Your Health.




woman giving young girl an asthma treatment

What is asthma?

Asthma is an inflammatory disease of the lung. This inflammatory process can occur along the entire airway from the nose to the lung. Once the airway becomes swollen and inflamed, it becomes narrower, and less air gets through to the lung tissue. This causes symptoms like wheezing, coughing, chest tightness, and trouble breathing. During an asthma attack, the muscles around the airways tighten up and the asthma symptoms become even worse than usual.

Once considered a minor ailment, asthma is now the most common chronic disorder in childhood. The prevalence of asthma has progressively increased over the past 15 years. In the United States alone, nearly 40 million people — 13.3 percent of adults and 13.8 percent of children — have been diagnosed with asthma.

Does asthma run in families?

Asthma does run in families, which suggests that genetics play an important role in the development of the disease. If one or both parents have asthma, the child is much more likely to develop the condition — this is known as genetic susceptibility. An NIEHS study of 615 Mexico City families showed that variations in two genes, ORMDL3 and GSDML, were associated with an increased risk of childhood asthma. These results confirm a similar study conducted among European populations.

Simple steps for decreasing indoor allergens:

  • Encase mattresses, pillows, and box springs in allergen-impermeable covers
  • Replace carpeting with smooth surfaces such as hardwood or vinyl
  • Steam clean carpets and floor mats every 8 weeks
  • Vacuum carpets and upholstered furniture every week
  • Wash sheets and blankets in hot water every week

Are allergies related to asthma?

Asthma can be triggered by substances in the environment called allergens. Indoor allergens from dust mites, cockroaches, dogs, cats, rodents, molds, and fungi are among the most important environmental triggers for asthma.

NIEHS scientists, along with researchers from the U.S. Department of Housing and Urban Development, conducted an extensive survey known as the National Survey of Lead Hazards and Allergens in Housing, which showed that 46 percent of the homes had dust mite allergens high enough to produce allergic reactions, while nearly 25 percent of the homes had allergen levels high enough to trigger asthma symptoms in genetically susceptible individuals. The survey also showed that nearly two-thirds of American homes have cockroach allergens.

What can I do to reduce allergens and asthma attacks?

NIEHS scientists identified several strategies that reduce indoor allergens and asthma symptoms — cockroach extermination, thorough professional cleaning, and in-home visits to educate the occupants about asthma management. Using these strategies, cockroach allergens were reduced by 84 percent, well below the threshold for producing asthma symptoms.

Other research showed that some simple steps — washing bedding in hot water; putting allergen-impermeable covers on pillows, box springs, and mattresses; and vacuuming and steam cleaning carpets and upholstered furniture — can significantly reduce dust mite allergen levels.

smog city
Children living within 150 meters of a freeway were more likely to be diagnosed with asthma than children who lived further away.

What about the air pollution outside? 

While much of the asthma research has focused on indoor allergens, scientists know that outdoor pollution also plays a major role. NIEHS-funded researchers at the Keck School of Medicine of the University of Southern California studied air pollution in 10 Southern California cities and found that children living within 150 meters of a freeway were more likely to be diagnosed with asthma than children who lived further away. The researchers also found that children who had higher levels of nitrogen dioxide in the air around their homes were more likely to develop asthma symptoms. Nitrogen dioxide is one of many pollutants emitted from motor vehicles.

Scientists with the Columbia Center for Children’s Environmental Health found that New York City mothers who were exposed during pregnancy to both polycyclic aromatic hydrocarbons, air pollutants from gasoline and other fossil fuels, and secondhand tobacco smoke had children who were more likely to have asthma.

Research conducted by NIEHS-funded scientists at Yale University also suggests that asthmatic children who use medication to control asthma symptoms are particularly vulnerable to the effects of ground-level ozone, a highly reactive form of oxygen that is a primary ingredient of urban smog.

This content is available to use on your website.
Please visit NIEHS Syndication to get started.

Impacts of Climate Change on Human Health in the United States: A Scientific Assessment

Impacts of Climate Change on Human Health in the United States: A Scientific Assessment

Climate change is affecting the health of Americans. As the climate continues to change, the risks to human health will grow, exacerbating existing health threats and creating new public health challenges. This assessment significantly advances what we know about the impacts of climate change on public health, and the confidence with which we know it. While all Americans will be affected by climate change, the report recognizes populations of concern, such as children, the elderly, outdoor workers, and those living in disadvantaged communities, who are disproportionately vulnerable.

Read the full report online
Video: Impacts of Climate Change on Human Health in the United States: A Scientific Assessment

Content courtesy of the Centers for Disease Control and Prevention (CDC)

Health Studies & Clinical Trials 

What NIEHS is Doing on Asthma 

Research Groups and Efforts

General Information 

Using Inhalers -Video tutorial on model differences and proper usage

For Educators 

Related Topics 

Research Links 

  • Eckel SP, et al., 2011. Residential Traffic-Related Pollution Exposures and Exhaled Nitric Oxide in the Children’s Health Study. Environ Health Perspect 119(10): 1472-1477. [Abstract]
  • Henderson SB, et al., 2011. Three Measures of Forest Fire Smoke Exposure and Their Associations with Respiratory and Cardiovascular Health Outcomes in a Population-Based Cohort. Environ Health Perspect 119(9): 1266-1271. [Abstract]
  • Karine A, et al., 2011. Application of Computational Systems Biology to Explore Environmental Toxicity Hazards. Environ Health Perspect 119(12): 1754-1759. [Abstract]
  • Lobdell DT, et al., 2011. Feasibility of Assessing Public Health Impacts of Air Pollution Reduction Programs on a Local Scale: New Haven Case Study. Environ Health Perspect 119(4): 487-493. [Abstract]
  • Rappold AG, et al., 2011. Peat Bog Wildlife Smoke Exposure in Rural North Carolina Is Associated with Cardiopulmonary Emergency Department Visits Assessed through Syndromic Surveillance. Environ Health Perspect 119(10): 1415-1420. [Abstract]
  • Roda C, et al., 2011. Formaldehyde Exposure and Lower Respiratory Infections in Infancts: Findings from the PARIS Cohort Study. Environ Health Perspect 119(11): 1653-1658. [Abstract]
  • Rosa MJ, et al. 2011. Prenatal exposure to polycyclic aromatic hydrocarbons, environmental tobacco smoke and asthma. Respir Med 105(6):869-876. [Abstract]
  • Spira-Cohen A, et al., 2011. Personal Exposures to Traffic-Related Air Pollution and Acute Respiratory Health among Bronx Schoolchildren with Asthma. Environ Health Perspect 119(4): 559-565. [Abstract]
  • Wu H, et al. 2009. Genetic variation in ORM1-like 3 (ORMDL3) and gasdermin-like (GSDML) and childhood asthma. Allergy 64(4):629-635. [Abstract]
  • Gauderman WJ, et al. 2005. Childhood asthma and exposure to traffic and nitrogen dioxide. Epidemiology 16(6):737-743. [Abstract]
  • Arbes SJ Jr, et al. 2003. Abatement of cockroach allergen (Bla g 1) in low-income, urban housing: A randomized controlled trial. J Allergy Clin Immunol 112(2):339-345. [Abstract]
  • Arbes SJ Jr, et al. 2003. House dust mite allergen in U.S. beds: Results from the First National Survey of Lead and Allergens in Housing. J Allergy Clin Immunol 111(2):408-414. [Abstract]
  • Gent JF, et al. 2003. Association of low-level ozone and fine particles with respiratory symptoms in children with asthma. JAMA 290(14):1859-1867. blastocyst development. Cell Stem Cell. 14(5):575-91. [Abstract]
  • Vojta PJ, et al. 2001. Effects of physical interventions on house dust mite allergen levels in carpet, bed, and upholstery dust in low-income, urban homes. Environ Health Perspect 109(8):815-819. [Abstract]

Share This Page:

Page Options:

Request Translation Services