Indoor and Outdoor Air Pollution Create Health Disparities for Rural Patients with Asthma

Children of the Navajo Nation have particularly high prevalence and severity of asthma. Andrew H. Liu, MD, of the Children’s Hospital Colorado, shared reasons why, as well as information about a new initiative to intervene during a session at the 2018 AAAAI Annual Meeting.

Navajo Nation is a sovereign nation of Native American within the United States; the territory covers about 27,000 square miles and encompasses parts of Utah, Arizona, and New Mexico. Its population is approximately 250,000, about 40% of which falls below the poverty line. Navajo Nation’s population is made up of 44% children, who experience asthma at a rate of 13% compared with 8.6% of US children.

Dr. Liu presented data from a review article published in 2018 in the Annals of the American Thoracic Society by Lowe et al that examined environmental risk factors for asthma in this population. One key factor was indoor pollutants from burning coal. Many Navajo families live in hogans—small, one-room, nonventilated structures. Although most have wood-burning stoves, coal is the preferred material to burn. However, coal burns hotter than wood, which causes cracking in the stoves that are generally 10 years old; consequently, many families have stoves that are damaged and poorly ventilated.

Additional irritants that increase risk and severity are:

  • Dust/dust storms
  • Coal plants
  • Diesel fumes—Navajo Nation children spend 4-6 hours per day riding buses to school, and buses are not regulated
  • Aeroallergens
  • Mold and dampness
  • Tobacco
  • Metals
  • Respiratory viruses—Navajo Nation children have higher susceptibility to respiratory syncytial virus

In addition to the individual exposure issues, Dr. Liu encouraged the audience to think about the added effects of age of exposure (infants breathe faster, for example), dose of exposure, combinations of exposures (which can exponentiate toxicity), and increased susceptibility due to genetics or other reasons like underlying disease.

Dr. Liu then reviewed the work of Aaron Kobernick, MD, MPH, an allergist and immunologist in Utah who spent four years in the Chinle chapter of Navajo Nation to study asthma in the population. Dr. Kobernick assessed many facets, finding that low numbers of Navajo Nation children are receiving guideline-based care; most are not adhering to treatment; and healthcare professionals need significant support to address gaps in care. Those findings will be published this year.

A current six-year project funded by the National Heart, Lung, and Blood Institute is supporting investigators and programs to improve asthma control in the population. Essential to the “Asthma Empowerment” project have been many community engagement meetings and a “circuit rider”—Peter Nez, a member of Navajo Nation who is also member of the research team and serves as a cultural link between the two.

The initiative is also implementing an asthma toolkit program to teach caregivers how to diagnose and manage asthma and asthma education and care coordination through public and private schools in three Navajo Nation chapters.

The second half of the presentation, delivered by Anahi Yáñez, MD, of the Research Center for Allergy and Respiratory Diseases in Buenos Aires, Argentina, addressed the effects of air pollution and climate change on the incidence of respiratory allergic diseases in Latin America. The area incudes 20 countries and 600,000 million people, including about 40 million of whom have asthma.

According to the International Study of Asthma and Allergies in Childhood, asthma prevalence in children varies widely in Latin America, but most areas have a rate of current symptoms and lifetime asthma of ≥15%. Although all regions are affected, she said, low-income populations experience the most impact.

Although not many studies on the topic have been performed in Latin America, Dr. Yáñez said, research has revealed a significant rise in the prevalence of allergic respiratory diseases and bronchial asthma over the past two decades. The upturn appears to be related to an increase in the atmospheric concentration of gases and breathable particulate matter, she said. The ESCALE study, for example, confirmed ambient concentrations of particulate matter and ozone and their effects on mortality from respiratory diseases. Dr. Yáñez reviewed literature to highlight the significant atmospheric pollutants in the open air, specifically particulate matter, ozone, sulfur dioxide, nitrogen, carbon monoxide, and lead.


Dr. Yáñez also reviewed the effects of indoor air pollution in Latin America, particularly indoor smoke. She emphasized that the effects are largely dependent on type of fuel, type of stove, location of stove, kitchen location, ventilation, and amount of time spent in polluted environments (e.g., women and young children who spend more time in the home tend to have more exposure). Also highlighted were the possible inflammatory effects of combined exposures to air pollution and allergens, such as microscopic particles released by plants, specifically pollen and soybean hull in rural areas.


Due to the lack of studies but the serious effects of exposure, Dr. Yáñez urged attendees to conduct research on the topic and then implement interventional and environmental policies.


Presentation 2305: Indoor and Outdoor Air Pollution Create Health Disparities for Rural Asthma Patients