Specific Air Pollutants Linked to Asthma Attacks in Urban Children

In a study of children living in urban neighborhoods across the United States, nearly 30% of asthma attacks were non-viral and linked to specific air pollutants and ozone layer, emphasizing the need to reduce elevated levels of air pollution to counteract respiratory illnesses among children and young adults.

“The strong association this study demonstrates between specific air pollutants among children in impoverished urban communities and non-viral asthma attacks further augments the evidence that reducing air pollution would improve human health,” said Hugh Auchincloss, MD, acting director of the National Institute of Allergy and Infectious Diseases (NIAID), part of National Institutes of Health (NIH), in a statement.

This retrospective data analysis study was published in The Lancet Planetary Health, and is the first of its kind to link specific air pollutants in urban areas todistinct changes in the airways during an asthma attack.

In this study, the researchers examined air pollution levels to the prevalence of non-viral asthma attacks among a cohort of 208 children aged 6-17 living in low-income urban areas across the US, who were diagnosed with exacerbation-prone asthma between October 7, 2015, and October 18, 2016.

Another group included 419 children aged 6-20 living in similar areas with persistent allergic asthma between October 23, 2006, and March 25, 2008.

From both cohorts, a total of 357 (213 males, 144 females) participants were included in the analysis.

The researchers followed these children prospectively for up to 2 respiratory illnesses or approximately 6 months, whichever occurred first.

The researchers identified that increased air quality index values, measured by fine particulate matter and ozone, were associated with increased asthma attacks, and decreases in pulmonary function that occurred in the absence of a viral infection.

Furthermore, these air pollutants were associated with altered gene expression in coordinated inflammatory pathways with increased epithelial induction of tissue kallikreins, mucus hypersecretions, and barrier functions with increased type-2 inflammation.

As a result, nearly 30% of asthma attacks found in participants were non-viral and linked to elevated air pollutants, which is 2-3 times the proportion seen in non-urban children, according to previous reports.

Although the researchers acknowledged that this study was limited given its observational nature, they believe that the findings of this study provide insight and inform novel asthma management strategies for children living in low-income urban areas.

The researchers called for future development and testing to examine if the prevention of reduction of specific air pollutants would result in lower cases of non-viral asthma attacks in children.

Treatments to specifically counteract elevated pollution levels as well as personalized air pollutant level monitoring devices are some possible solutions that were suggested by the researchers.

“Our findings suggest that moderate increases in local air pollution relative to the US national air quality standards adversely affect these [low-income urban] susceptible populations,” wrote the researchers of this study. “This association suggests either that exposure to mixtures of pollutants over several days at low concentrations can trigger exacerbations or that high AQI levels exist in these urban communities but are not well captured by regionally reported AQI values on the basis of EPA monitors and public data.”

Reference

Altman MC, Kattan M, O'Connor GT, et al. Associations between outdoor air pollutants and non-viral asthma exacerbations and airway inflammatory responses in children and adolescents living in urban areas in the USA: A retrospective secondary analysis. Lancet Planetary Health. 2023;7(1). doi:10.1016/s2542-5196(22)00302-3