Children’s Environmental Health in Michigan

Respiratory Health and Asthma: Criteria Air Pollutants

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Children are particularly vulnerable to outdoor air pollutants because they breathe more rapidly, take in more air per pound of body weight, have narrower airways that are more susceptible to irritation and obstruction, and tend to spend more time outdoors for physical activity than adults do (AAP 2003). In fact, one study found that, on average, children are engaged in outdoor physical activity up to five times longer than adults (Wiley et al. 1991a; Wiley et al. 1991b), thus increasing the potential for exposure to outdoor air pollutants compared to adults.

Recent studies have reported a significant association between various outdoor air pollutant levels and a diverse array of preventable respiratory illnesses such as reduced lung function, inflammation of the lungs, asthma attacks, which can lead to excess respiratory hospital admissions, and even premature death. Furthermore, some studies have found associations between health outcomes and pollution levels that are in compliance with current air quality standards (Gent et al. 2003; Trasande and Thurston 2005). Hospital admissions for asthma have been shown to increase when outdoor air pollution levels are elevated, especially in urban areas, and respiratory illnesses caused or exacerbated by exposure to outdoor air pollutants can result in increased school absenteeism (AAP 2003; Bener et al. 2007; Gilliland et al. 2001). In children, acute health effects that are associated with exposure to outdoor air pollution include wheezing, coughing, transient decreases in lung function, lower respiratory tract infections, and other negative effects on respiratory health. (AAP 2003; Tzivian 2011). Also, children with asthma are more susceptible to the effects of air pollution, and can experience more serious symptoms than other children.

Residents in some parts of Michigan experience significantly worse air quality than residents in most other parts of the country due to air pollution. The American Lung Association (ALA) ranked Wayne County, Michigan, as the ninth most polluted county in the country for short-term, fine particulate matter pollution, known as PM2.5, particles that are less than 2.5 micrometers in size. “Short-term” refers to data collected at a specific time, as opposed to “long-term” data that indicate overall background levels. PM10 refers to “inhalable course particles” ranging from 2.5 to 10 micrometers (microns) in diameter, while PM2.5 refers to “fine particulate matter” 2.5 micrometers in diameter or less (about ¼ the size of a grain of salt) (EPA 2009). According to the ALA’s report “State of the Air: 2007,” the people of Wayne County, an area with a population of approximately 2 million people, were greatly affected by a range of respiratory illnesses in the year 2005 including:

  • 49,427 cases of pediatric asthma
  • 130,544 cases of adult asthma
  • 59,355 cases of chronic bronchitis
  • 25,424 cases of emphysema

In addition, the ALA’s report “State of the Air: 2007” ranked the Grand Rapids-Muskegon-Holland metropolitan area of Michigan as the 24th most polluted area in the country for ozone pollution. The ALA report showed that the population in this area, a population of approximately 1.3 million, was also, greatly affected by a range of related respiratory illnesses in 2005 including:

  • 31,283 cases of pediatric asthma
  • 87,591 cases of adult asthma
  • 39,147 cases of chronic bronchitis
  • 16,094 cases of emphysema

Children in Michigan have the potential to be exposed to a variety of different air pollutants. Given the multitude of health effects that may be associated with exposure to outdoor air pollutants and the vulnerability of children to these types of exposure, it is critical to evaluate means of reducing exposures to hazardous air pollution. This section on outdoor air pollutants addresses sources, exposures, and respiratory health effects associated with three classes of outdoor air pollutants: diesel exhaust, certain pesticides, and the six air pollutants that are considered to be “criteria air pollutants” under the National Ambient Air Quality Standards – carbon monoxide, lead, nitrogen dioxide, particulate matter (PM10 and PM2.5), ozone, and sulfur dioxide.

The following three sections of this chapter will investigate these pollutants, provide analysis of the effectiveness of policy measures in Michigan and other states and recommend best practices for addressing outdoor air quality issues in Michigan.


American Academy of Pediatrics (AAP). 2003. Pediatric Environmental Health, 2nd ed. American Academy of Pediatrics. ISBN:1-58110-111-2. American Lung Association (ALA). 2007. State of the Air: 2007. Downloaded from:

Bener A, Ehlayel M, Sabbah A. 2007. The pattern and genetics of pediatric extrinsic asthma risk factors in polluted environment. European Annals of Allergy and Clinical Immunology 39(2): 58-63.

Gent JF, Triche EW, Holford TR, et al. 2003. The Association of Low Level Ozone and Fine Particles with Respiratory Symptoms in Children with Asthma. Journal of the American Medical Association 290:1859-67.

Gilliland FD, Berhane K, Rappaport EB, Thomas DC, Avol E, Gauderman WJ, et al. 2001 The effects of ambient air pollution on school absenteeism due to respiratory illnesses. Epidemiology 12(1):43-54.

Tzivian L. 2011. Outdoor air pollution and asthma in children. Journal of Asthma 48(5): 470-81.

Trasande L, Thurston G. 2005. The Role of Air Pollution in Asthma and Other Pediatric Morbidities. Journal of Allergy and Clinical Immunology 115:689-99. United States Environmental Protection Agency. 2009. Particulate Matter. Accessed August 25, 2009 at:

Wiley JA, Robinson JP, Cheng YT, et al. Study of children’s activity patterns. Sacramento (CA): Survey Research Center, University of California, California Air Resources Board; 1991a. Final report contract no. A733–149.

Wiley JA, Robinson JP, Piazza T, et al. Activity patterns of California residents. Sacramento (CA): Survey Research Center, University of California, California Air Resources Board; 1991b. Final report contract no. A6-177-33-149.