Continuous in-home PM2.5 concentrations of smokers with and without a history of respiratory exacerbations in Iowa, during and after an air purifier intervention

Abstract

Background: Americans spend most of their time indoors. Indoor particulate matter (PM) 2.5 µm and smaller (PM_2.5) concentrations often exceed ambient concentrations. Therefore, we tested whether the use of an air purifying device (electrostatic precipitator, ESP) could reduce PM_2.5 in homes of smokers with and without respiratory exacerbations, compared with baseline.

Methods: We assessed PM_2.5 concentrations in homes of subjects with and without a recent (≤3 years) history of respiratory exacerbation. We compared PM_2.5 concentrations during 1 month of ESP use with those during 1 month without ESP use.

Results: Our study included 19 subjects (53-80 years old), nine with a history of respiratory exacerbation. Geometric mean (GM) PM_2.5 and median GM daily peak PM_2.5 were significantly lower during ESP deployment compared with the equivalent time-period without the ESP (GSD = 0.50 and 0.37 µg/m³, respectively, p < 0.001). PM_2.5 in homes of respiratory exacerbators tended (p < 0.14) to be higher than PM_2.5 in homes of those without a history of respiratory exacerbation.

Conclusions: Subjects with a history of respiratory exacerbation tended to have higher mean, median, and mean peak PM_2.5 concentrations compared with homes of subjects without a history of exacerbations. The ESP intervention reduced in-home PM_2.5 concentrations, demonstrating its utility in reducing indoor exposures.

Novelty of study: Our work characterizes PM air pollution concentrations in homes of study subjects with and without respiratory exacerbations. We demonstrate that PM concentrations tend to be higher in homes of participants with respiratory exacerbations, and that the use of an inexpensive air purifier resulted in significantly lower daily average PM concentrations than when the purifier was not present. Our results provide a helpful intervention strategy for purifying indoor air and may be useful for susceptible populations.

Keywords: Air pollution (or Air quality); Environmental monitoring; Exposure assessment; Particulate matter; Pulmonary disease.

Figure 1.

Log-transformed PM_2.5 concentrations during and after ESP deployment. Each line connects a single subject’s PM_2.5 without and with an ESP. Differences in PM_2.5 before- and after- ESP deployment were significant, except for the mean daily peak PM_2.5.

Figure 2.

Average daily, average peak daily, and median peak daily PM_2.5 concentrations, grouped by respiratory exacerbation status; to be considered within the exacerbator group, subjects had experienced ≥1 exacerbation per year within the previous three years (2015–2017), while non-exacerbators had not experienced any exacerbations within the prior three years. The box plots represent the interquartile range (Q1-Q3, or 25–75 percentile) and lines inside indicate means. Whiskers represent 95% confidence intervals.