The Association Between Air Pollution and Hospitalization of Patients With Idiopathic Pulmonary Fibrosis in Chile: A Daily Time Series Analysis.

Background: Idiopathic pulmonary fibrosis (IPF) causes progressive dyspnea, hypoxemia, and death within a few years. Little is known about the effect of air pollution on disease exacerbations.

Research Question: Are acute increases in air pollution a risk factor for hospitalization of patients with a primary diagnosis of IPF.

Study Design And Methods: Hospital admissions for IPF are coded J84.1 by the International Classification of Disease, 10th Revision. Using ambient air pollution and climate data from seven air monitoring stations distributed in the seven urban centers in Santiago, Chile, along with daily patient hospitalization data from 2001 to 2012, a linear association between daily ambient air pollution and daily J84.1 hospital admissions was tested using generalized linear models.

Results: Average pollutant levels for all regions were as follows: carbon monoxide was 0.96 ppm, ozone was 64 ppb, nitrogen dioxide (NO) was 43 ppb, sulfur dioxide was 9 ppb, particulate matter < 2.5 μm in diameter was 29 μg/m and particulate matter < 10 μm in diameter (PM) was 67 μg/m. For the combined Santiago area, relative risk estimates of J84.1 hospitalizations for all pollutants (except ozone), adjusted for age, sex, and weather were statistically significant. In the two-pollutant models, the significance of NO and PM persisted despite adjustments for each of the other measured pollutants.

Interpretation: Our findings suggest that acute increases in air pollution are a risk factor for hospitalization of patients with a primary diagnosis of IPF.