Association Between Bedroom Particulate Matter Filtration and Changes in Airway Pathophysiology in Children With Asthma

Abstract

IMPORTANCE Fine particles (particulate matter 2.5 μm [PM 2.5 ]), a ubiquitous air pollutant, can deposit in the small airways that play a vital role in asthma. It appears to be unknown whether the use of a PM 2.5 filtration device can improve small airway physiology and respiratory inflammation in children with asthma.OBJECTIVE To discover what pathophysiological changes in the small airways are associated with using a PM 2.5 -removing device in the bedrooms of children with asthma. DESIGN, SETTING, AND PARTICIPANTSChildren with mild or moderate asthma were enrolled in this double-blind, crossover study. The participants used a true filtration device and a sham filtration device in their bedrooms in a random order for 2 weeks each with a 2-week washout interval. The study was conducted in a suburb of Shanghai, China, during a low-ozone season.EXPOSURES Ozone and PM 2.5 were measured inside bedrooms and outside a window.MAIN OUTCOMES AND MEASURES Impulse oscillometry, spirometry, and fractional exhaled nitric oxide were measured at the beginning and the end of each intervention. Peak expiratory flow was measured twice daily at home. RESULTS Forty-three children (5-13 years old; 26 boys [60%]) participated. Outdoor 24-hour mean PM 2.5 concentrations were moderately high, ranging from 28.6 to 69.8 μg/m 3 (median, 53 μg/m 3 ). During true filtration, bedroom PM 2.5 concentrations were a mean (SD) of 63.4% (35.9%) lower than during sham filtration. Compared with sham filtration, true filtration was significantly associated with improved airway mechanics, reflected in a 24.4% (95% CI, 11.8%-37.1%) reduction in total airway resistance, a 43.5% (95% CI, 13.7%-73.3%) reduction in small airway resistance, a 22.2% (95% CI, 2.2%-42.2%) reduction in resonant frequency, and a 73.1% (95% CI, 0.3%-145.8%) increase in airway reactance. True filtration was also associated with significant improvements in fractional exhaled nitric oxide (a 27.6% [95% CI, 8.9%-42.4%] reduction) and peak expiratory flow (a 1.6% [95% CI, 0.8%-2.5%] increase). These improvements were significantly associated with bedroom PM 2.5 reduction. Improvements in small airway function were nonsignificant (8.4% [95% CI, −1.4% to 18.3%]) in all participants but significant (13.2% [95% CI, 1.2%-25.1%]) in participants without eosinophilic airway inflammation at baseline. No improvements were observed for forced vital capacity, forced expiratory volume during the first second, and the ratio of these in all participants or subgroups.CONCLUSIONS AND RELEVANCE Per these results, indoor PM 2.5 filtration can be a practical method to improve air flow in an asthmatic lung through improved airway mechanics and function as well as reduced inflammation. This warrants a clinical trial to confirm.

Real‐time measurements of PM2.5and ozone to assess the effectiveness of residential indoor air filtration in Shanghai homes

“…Nonetheless, our results indicate relatively low indoor O 3 concentrations underscoring the importance of indoor PM 2.5 exposures on the health of children with asthma in our study. Indeed, PM 2.5 and not O 3 was found to be related to lung inflammatory stress in our study group 41,42 …”

“…During this study, we also measured volatile organic compounds (VOCs) and aldehydes, 37,38 and used low flow rate (2‐4 lpm), filter‐based approaches to measure PM 2.5 mass, chemical composition, and toxicity 39,40 ; these measurements are discussed in other publications. In addition, health indicator measurements were taken before and after intervention, and the results are discussed elsewhere 41,42 …”

Assessing Impact of Household Intervention on Indoor Air Quality and Health of Children with Asthma in the US-Mexico Border: A Pilot Study

“…Our study has several limitations. Firstly, the total study period, including pre-and postintervention periods, was 15 days so that it might be a shorter time to see substantial changes in indoor air condition and participants' health outcomes when compared with other similar studies that had at least 4 weeks [40,45]. However, we observed a 12% significant reduction in the mean PM 2.5 level and some positive outcomes in children with asthma, providing a promising basis for future studies.…”

“…Fourth, due to the small sample size, we could not use the statistical model to adjust the characteristics of socioeconomic status, which may affect asthma severity. Given that similar studies included more than 40 participants [ 39 , 40 , 45 ], the future study should have more sample sizes to obtain better results by conducting a statistical analysis. However, the socioeconomic status of participating families in this study is homogeneous as low-education and low-income Hispanic population supported by public health insurance aid was recruited.…”

Negative ions offset cardiorespiratory benefits of PM 2.5 reduction from residential use of negative ion air purifiers

“…Previous studies have shown that high‐efficiency particulate air (HEPA) purifiers were effective in reducing indoor PM levels and improving occupants’ cardiopulmonary health 6‐12 . However, the effectiveness of HEPA purifiers relies on regular replacement of filters, which could be costly and time‐consuming.…”