Abstract
Background Particulate air pollution increases mortality and morbidity related to respiratory and cardiovascular diseases, especially for susceptible individuals such as the elderly, possibly through oxidative stress, systemic inflammation and endothelial dysfunction. In a previous study, 48 hours air filtration in the homes of 41 healthy subjects (60 to 75 years) reduced PM2.5 concentrations from 12.6 to 4.7µg/m3 and improved the microvascular function by 8%(Brauner et al., 2008). Aims In this study we examined potential beneficial effects of two weeks air filtration in the homes of an elderly population, including people taking vasoactive drugs. Methods Re-circulating custom built particle filtration units with or without the inclusion of a high-efficiency particle air (HEPA) filters were used in a randomized, double-blind, crossover intervention study in 27 homes with 48 nonsmoking subjects (51 to 81 years), exposed to consecutive 2-week periods of either particle-filtered or non-filtered air in their living and bedrooms. At the beginning of the study (baseline) and at day 2, 7 and 14 after each exposure scenario we measured blood pressure, microvascular- and lung function and collected saliva, urine and blood samples to quantify different hematological parameters and markers of inflammation, monocyte surface markers and oxidative stress. Results The inclusion of particle air filters changed the concentration of PM2.5 from approximately 8 to 4 µg/m3 and the ultrafine particle number count from 7669 to 5352 particles/cm3. No statistically significant effects of filtration were observed on microvascular- and lung function or the biomarkers we measured among all subjects or in the subgroups taking (n=15) or not taking vasoactive drugs (n=33). Conclusion With the exposure gradient achieved no beneficial effect of air filtration for two weeks could be documented in this elderly population, irrespective of use of vasoactive drugs.
Highlights
Exposure to particulate air pollution increases respiratory and cardiovascular morbidity and mortality, especially in elderly, possibly through inflammation and vascular dysfunction
The air filtration intervention in the 27 study homes resulted in a reduction of 30% in Particle number concentrations (PNC) in the living room and close to 50% of PM2.5 in both living room and bedroom (Table 2)
The reductions in polycyclic aromatic hydrocarbons (PAH), black carbon (BC) and ultraviolet-absorbing particulate matter (UVPM) were similar to the PM2.5 reduction
Summary
Exposure to particulate air pollution increases respiratory and cardiovascular morbidity and mortality, especially in elderly, possibly through inflammation and vascular dysfunction. Exposure to particulate air pollution increases mortality and morbidity related to respiratory and cardiovascular diseases especially among susceptible individuals such as the elderly and people with pre-existing lung- and heart disease [1]. The underlying biological mechanisms are considered to include oxidative stress and inflammation For cardiovascular disease these mechanisms include the pulmonary release of inflammatory and vasoactive molecules into the circulation, altered cardiac autonomic function, altered balance between coagulation and fibrinolysis, endothelial and microvascular dysfunction, atherosclerosis progression and plaque instability [2]. Biomarkers related to risk of cardiovascular and other diseases appear more strongly associated with personal exposure to particles than with ambient particulate air pollution levels [10,11]. Substantial reductions in exposure to particles can be achieved by portable air filtration units in the indoor environment allowing assessment of causality, understanding mechanistic endpoints, identification of relevant sources and development of large scale long-term interventions in relevant risk groups
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