Asthma Associated with Greater Air Particulate Matter, Ozone in Urbanized Areas

New research was conducted regarding air pollution and other elements affecting asthma cases in urbanized settings.

Asthma exacerbations and diminished pulmonary function were associated with higher air quality index ratings resulting mostly from higher particulate matter (PM) 2.5 and ozone (O3) concentrations, according to new findings.1

This research was conducted to address the severe increases in asthma for children in urban areas, to assess the effects of regional pollutants, lung functioning, and other elements in the absence of a virus in the respiratory system.

The study was authored by Matthew C. Altman, MD, from the Systems Immunology Division of the Benaroya Research Institute in Seattle.

“We aimed to investigate the associations between regional air pollutant concentrations, respiratory illnesses, lung function, and upper airway transcriptional signatures in children with asthma, with particular focus on asthma exacerbations occurring in the absence of respiratory virus,” Altman and colleagues wrote.

Research and Methods

The investigators conducted a retrospective data analysis, using information from the MUPPITS1 cohort and using the ICATA cohort to determine the validation of their findings.2,3

In the MUPPITS1 group, the research team had assessed 208 children (ages 6 to 17) who were residents of urban areas over 9 American cities and had exacerbation-prone cases of asthma. The study involved monitoring the participants during their respiratory illnesses.

The investigators used data from the 419 participants between the ages of 6 and 20 in the ICATA group. Each of these recruited participants across 8 American cities had reported having persistent allergic asthma.

The team also noted that they had included participants from the ICATA group with nasal samples that had been taken during an illness or visit, and they included MUPPITS1 participants who had determined that they had a respiratory illness at any point during their follow-up times.

In order to conduct their research, the investigators utilized the Environmental Protection Agency’s air pollutant concentrations and air quality index values for PM 2.5, PM 10, O3, NO2, SO2, CO, and Pb during the time periods of the 2 cohorts.

The team then matched values and concentrations, working to determine what were the associations between regional asthma exacerbations, concentrations of air pollutants, pulmonary function, respiratory illnesses, and upper airway transcriptional signatures.

Study Results

The investigators ended up concluding that of each of the study participants in both cohorts that were analyzed, higher air quality index values—which had been promoted significantly by higher O3 and PM 2.5 concentrations—had a strong association with exacerbations of asthma.

The team also concluded that the exacerbations were strongly associated with diminished pulmonary function for participants, which they noted had happened without a provoking viral infection.

The investigators added that “individual pollutants were significantly associated with altered gene expression in coordinated inflammatory pathways, including PM 2.5 with increased epithelial induction of tissue kallikreins, mucus hypersecretion, and barrier functions and O3 with increased type-2 inflammation.”

Overall, the data led the investigators to the conclusion, for asthma exacerbations in younger urban residents, pollution in the air is a major independent risk factor. They added that air pollution was found to be linked to asthma exacerbations in specific inflammatory pathways.

The investigators noted that additional research into the aforementioned mechanistic pathways may help asthma prevention and management in the future.


  1. 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. The Lancet Planetary Health.
  2. Altman MC, Gill MA, Whalen E, et al. Transcriptome networks identify mechanisms of viral and nonviral asthma exacerbations in children. Nat Immunol. 2019; 20: 637-651.
  3. Busse WW, Morgan WJ, Gergen PJ, et al. Randomized trial of omalizumab (anti-IgE) for asthma in inner-city children. N Engl J Med. 2011; 364: 1005-1015