This article is more than 5 years old. Information may no longer be current.

Improved air quality decreases symptoms of bronchitis

Patients with and without asthma showed significant decreases in symptoms of bronchitis when exposed to lower concentrations of ozone, nitrogen dioxide and particular matter with an aerodynamic diameter of < 10 μm and < 2.5 μm, according to recent research.

“Decreases in ambient concentrations of nitrogen dioxide, ozone, [particulate matter, aerodynamic diameter < 10 μm] PM₁₀, and PM_2.5 were associated with statistically significant decreases in bronchitic symptoms in children with and without asthma,” Kiros Berhane, PhD, from the department of preventive medicine at the University of Southern California in Los Angeles, California, and colleagues wrote in their study. “While the study design does not establish causality, the findings support potential benefit of air pollution reduction on asthma control.”

Berhane and colleagues evaluated three cohorts of 4,602 pediatric patients between the ages of 5 years and 18 years across three different time periods of 1993 to 2001, 1996 to 2004 and 2003 to 2012, according to the abstract. Of these patients, there were 2,268 girls (49.3%) and 2,081 Hispanic white patients (45.2%) with data from at least two annual questionnaires. Nineteen percent of patients (n = 892) had asthma at 10 years of age.

The researchers analyzed the average concentrations of ozone, nitrogen dioxide and particulate matter with an aerodynamic diameter < 2.5 μm (PM_2.5) and < 10 μm (PM₁₀) across eight Southern California communities. They found an odds ratio (OR) of 0.79 for symptoms of bronchitis in children with asthma at 10 years for nitrogen dioxide (95% CI, 0.67-0.94), as well as a median reduction of 4.9 parts per billion (ppb) and an absolute decrease in prevalence of 10.1%, according to the abstract. The odds ratio for ozone was 0.66 (95% CI, 0.50-0.86) with a median reduction of 3.6 ppb and an absolute decrease in prevalence of 16.3%. The odds ratio for PM_2.5 was 0.68 (95% CI, 0.53-0.86) with a median reduction of 6.8 μg/m3 and an absolute decrease in prevalence of 15.4%, while the odds ratio for PM₁₀ was 0.61 (95% CI, 0.48-0.78) with a median reduction of 5.8 μg/m3 and an absolute decrease in prevalence of 18.7%.

In a subset of 3,710 pediatric patients without asthma, there was an odds ratio for nitrogen dioxide of 0.84 (95% CI, 0.76-0.92), an odds ratio for PM_2.5 of 0.79 (95% CI, 0.69-0.91), an odds ratio for PM₁₀ of 0.8 (95% CI, 0.70-0.92) and an odds ratio of 0.85 for ozone (95% CI, 0.74-0.97), according to the abstract. Among these patients, there was an absolute decrease in prevalence for nitrogen dioxide of 1.8%, a decrease of 2.3% for PM_2.5, a decrease of 2.2% for PM₁₀ and a decrease of 1.7% for ozone. Berhane and colleagues noted these associations were similar at age 15 years. – by Jeff Craven

Disclosure: The researchers report no relevant financial disclosures.