Cardiopulmonary Benefits of Reducing Indoor Particles
Cardiopulmonary Benefits of Reducing Indoor Particles
Study participants were 25 females and 10 males with a mean age of 23 ± 2 years and an average body mass index of 22 kg/m. All participants completed this study. According to the self-administrated questionnaire, they stayed indoors almost the entire time and stayed within the central urban area of Shanghai during the washout period. Furthermore, all participants remained healthy throughout the study period.
Before the intervention, the average PM2.5 concentration was comparable between the 2 groups. PM2.5 concentration was reduced markedly within the first 4 h of using the true air purifiers and remained stable over the rest of the 48-h period (Figure 1); in contrast, PM2.5 concentration in the sham-purification group was barely reduced, which suggests that closing the windows and doors did not efficiently block the penetration of outdoor PM2.5.
(Enlarge Image)
Figure 1.
Time-Varying PM2.5 Concentration in Outdoor Air, Sham-Purified Indoor Air, and True-Purified Indoor Air
The hourly concentrations in sham-purified air and true-purified air are the arithmetic averages of measurements in all dormitory rooms for a group. The hourly concentrations in outdoor air were measured on the rooftop of 1 dormitory building. PM2.5 = particulate matter <2.5 μm in aerodynamic diameter.
Table 1 summarizes the indoor and outdoor air pollutant concentrations and meteorologic parameters during the study periods. The average outdoor concentrations of PM2.5 were 103 μg/m, which were much higher than those in North America and Western Europe. The indoor PM2.5 concentration in rooms with a sham air purifier (96.2 μg/m) was only slightly lower than outdoor levels. In contrast, the mean PM2.5 concentration in rooms with a true air purifier was greatly reduced to 41.3 μg/m, 57% lower than the concentration of the sham group.
There were appreciable decreases in the levels of circulating biomarkers, BP, and FeNO in the true-purified air scenario compared with the sham-purified air scenario (Table 2); however, the differences in lung function indicators between the 2 scenarios were not significant. The Wilcoxon rank sum tests did not show any statistically significant differences in any of the health indicators between orders (p values ranging from 0.11 to 0.93), which suggests that there were no order effects or interactions between period and order.
Overview. In the mixed-effect model analysis, compared with participants in the sham purification group, those assigned to true air purification showed decreased levels of 4 blood biomarkers, BP, and FeNO, although nonsignificant improvement was also observed for lung function and several other blood biomarkers (Central Illustration, Table 3).
(Enlarge Image)
Central Illustration.
Air Purifiers and Cardiopulmonary Benefits: Percent Change in PM2.5 and Associated Cardiopulmonary Health Indicators Comparing the True-Purified Air Scenario to the Sham-Purified Air Scenario
Different colors represent different indicators of exposure and health: green = PM2.5; salmon = blood inflammation; gray = blood coagulation; blue = vasoconstriction; purple = lung function; yellow = blood pressure; and orange = respiratory inflammation. ACE = angiotensin-converting enzyme; CD40L = CD40 ligand; CRP = C-reactive protein; FeNO = fractional exhaled nitric oxide; FEV1 = forced expiratory volume in 1 s; FVC = forced vital capacity; MCP = monocyte chemoattractant protein; PAI = plasminogen activator inhibitor; PEF = peak expiratory flow; PM2.5 = particulate matter <2.5 μm in aerodynamic diameter; TNF = tumor necrosis factor; t-PA = tissue plasminogen activator.
Cardiovascular Health. All biomarkers of systematic inflammation, coagulation, and vasoconstriction decreased in response to the air purification intervention, although not all decreases were statistically significant. The intervention had significant effects on 3 of 8 inflammation markers and 1 of 4 coagulation markers and no significant effects on 2 vasoconstriction markers. The magnitude of the effects varied by biomarkers. For example, the intervention led to a significant geometric mean decrease of 17.5% (95% CI: 5.5% to 30.8%) in MCP-1, 68.1% (95% CI: 44.3% to 81.7%) in interleukin-1β, 32.8% (95% CI: 5.3% to 67.5%) in myeloperoxidase, and 64.9% (95% CI: 30.3% to 82.3%) in sCD40L. Systolic and diastolic BP were decreased significantly by 2.7% (95% CI: 0.4% to 5.1%) and 4.8% (95% CI: 1.2% to 8.5%) in geometric mean, respectively. However, pulse pressure was not altered with the introduction of air purifiers.
Respiratory Health. FeNO level was decreased significantly by 17.0% (95% CI: 3.6% to 32.5%) in geometric mean in the air purification intervention group. There was some indication of improved lung function associated with this intervention, but no evidence of statistical significance was observed.
Sensitivity Analysis. Overall, as indicated in Table 4, the sensitivity analysis showed positive associations of continuous exposure to indoor PM2.5 with circulating biomarkers, BP, and FeNO and inverse but nonsignificant associations with lung function. Inconsistent with the main analyses, lower indoor PM2.5 exposure was significantly associated with lower diastolic BP but not systolic BP; furthermore, unlike the main analyses, PM2.5 was inversely associated with tissue plasminogen activator, but its association with MCP-1 did not reach statistical significance.
Results
Descriptive Statistics
Study participants were 25 females and 10 males with a mean age of 23 ± 2 years and an average body mass index of 22 kg/m. All participants completed this study. According to the self-administrated questionnaire, they stayed indoors almost the entire time and stayed within the central urban area of Shanghai during the washout period. Furthermore, all participants remained healthy throughout the study period.
Before the intervention, the average PM2.5 concentration was comparable between the 2 groups. PM2.5 concentration was reduced markedly within the first 4 h of using the true air purifiers and remained stable over the rest of the 48-h period (Figure 1); in contrast, PM2.5 concentration in the sham-purification group was barely reduced, which suggests that closing the windows and doors did not efficiently block the penetration of outdoor PM2.5.
(Enlarge Image)
Figure 1.
Time-Varying PM2.5 Concentration in Outdoor Air, Sham-Purified Indoor Air, and True-Purified Indoor Air
The hourly concentrations in sham-purified air and true-purified air are the arithmetic averages of measurements in all dormitory rooms for a group. The hourly concentrations in outdoor air were measured on the rooftop of 1 dormitory building. PM2.5 = particulate matter <2.5 μm in aerodynamic diameter.
Table 1 summarizes the indoor and outdoor air pollutant concentrations and meteorologic parameters during the study periods. The average outdoor concentrations of PM2.5 were 103 μg/m, which were much higher than those in North America and Western Europe. The indoor PM2.5 concentration in rooms with a sham air purifier (96.2 μg/m) was only slightly lower than outdoor levels. In contrast, the mean PM2.5 concentration in rooms with a true air purifier was greatly reduced to 41.3 μg/m, 57% lower than the concentration of the sham group.
There were appreciable decreases in the levels of circulating biomarkers, BP, and FeNO in the true-purified air scenario compared with the sham-purified air scenario (Table 2); however, the differences in lung function indicators between the 2 scenarios were not significant. The Wilcoxon rank sum tests did not show any statistically significant differences in any of the health indicators between orders (p values ranging from 0.11 to 0.93), which suggests that there were no order effects or interactions between period and order.
Regression Results
Overview. In the mixed-effect model analysis, compared with participants in the sham purification group, those assigned to true air purification showed decreased levels of 4 blood biomarkers, BP, and FeNO, although nonsignificant improvement was also observed for lung function and several other blood biomarkers (Central Illustration, Table 3).
(Enlarge Image)
Central Illustration.
Air Purifiers and Cardiopulmonary Benefits: Percent Change in PM2.5 and Associated Cardiopulmonary Health Indicators Comparing the True-Purified Air Scenario to the Sham-Purified Air Scenario
Different colors represent different indicators of exposure and health: green = PM2.5; salmon = blood inflammation; gray = blood coagulation; blue = vasoconstriction; purple = lung function; yellow = blood pressure; and orange = respiratory inflammation. ACE = angiotensin-converting enzyme; CD40L = CD40 ligand; CRP = C-reactive protein; FeNO = fractional exhaled nitric oxide; FEV1 = forced expiratory volume in 1 s; FVC = forced vital capacity; MCP = monocyte chemoattractant protein; PAI = plasminogen activator inhibitor; PEF = peak expiratory flow; PM2.5 = particulate matter <2.5 μm in aerodynamic diameter; TNF = tumor necrosis factor; t-PA = tissue plasminogen activator.
Cardiovascular Health. All biomarkers of systematic inflammation, coagulation, and vasoconstriction decreased in response to the air purification intervention, although not all decreases were statistically significant. The intervention had significant effects on 3 of 8 inflammation markers and 1 of 4 coagulation markers and no significant effects on 2 vasoconstriction markers. The magnitude of the effects varied by biomarkers. For example, the intervention led to a significant geometric mean decrease of 17.5% (95% CI: 5.5% to 30.8%) in MCP-1, 68.1% (95% CI: 44.3% to 81.7%) in interleukin-1β, 32.8% (95% CI: 5.3% to 67.5%) in myeloperoxidase, and 64.9% (95% CI: 30.3% to 82.3%) in sCD40L. Systolic and diastolic BP were decreased significantly by 2.7% (95% CI: 0.4% to 5.1%) and 4.8% (95% CI: 1.2% to 8.5%) in geometric mean, respectively. However, pulse pressure was not altered with the introduction of air purifiers.
Respiratory Health. FeNO level was decreased significantly by 17.0% (95% CI: 3.6% to 32.5%) in geometric mean in the air purification intervention group. There was some indication of improved lung function associated with this intervention, but no evidence of statistical significance was observed.
Sensitivity Analysis. Overall, as indicated in Table 4, the sensitivity analysis showed positive associations of continuous exposure to indoor PM2.5 with circulating biomarkers, BP, and FeNO and inverse but nonsignificant associations with lung function. Inconsistent with the main analyses, lower indoor PM2.5 exposure was significantly associated with lower diastolic BP but not systolic BP; furthermore, unlike the main analyses, PM2.5 was inversely associated with tissue plasminogen activator, but its association with MCP-1 did not reach statistical significance.
Source...