Different cardiorespiratory effects of indoor air pollution intervention with ionization air purifier: Findings from a randomized, double-blind crossover study among school children in Beijing

Abstract

Indoor air pollution is associated with numerous adverse health outcomes. Air purifiers are widely used to reduce indoor air pollutants. Ionization air purifiers are becoming increasingly popular for their low power consumption and noise, yet its health effects remain unclear. This randomized, double-blind crossover study is conducted to explore the cardiorespiratory effects of ionization air purification among 44 children in Beijing. Real or sham purification was performed in classrooms for 5 weekdays. Size-fractionated particulate matter (PM), black carbon (BC), ozone (O3), and negative air ions (NAI) were monitored, and cardiorespiratory functions were measured. Mixed-effect models were used to establish associations between exposures and health parameters. Real purification significantly decreased PM and BC, e.g. PM0.5, PM2.5, PM10 and BC were dereased by 48%, 44%, 34% and 50% respectively. O3 levels were unchanged, while NAI was increased from 12 to 12,997 cm-3. Real purification was associated with a 4.4% increase in forced exhaled volume in 1 second (FEV1) and a 14.7% decrease in exhaled nitrogen oxide (FeNO). However, heart rate variability (HRV) was altered negatively. Interaction effects of NAI and PM were observed only on HRV, and alterations in HRV were greater with high NAI. Ionization air purifier could bring substantial respiratory benefits, however, the potential negative effects on HRV need further investigation.

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

“…Notably, the level of exposures may play crucial roles in the health effects of NI. Beneficial effects of NIs have been observed when the NI levels were comparable to those from the forest environment, 15 while adverse effects were documented for extremely high NI levels when generated by NIAPs 14,18 . In the present study, NI exposure duration was longer and NI levels were substantially higher as compared to a natural forest or oceanic exposure scenario and even to those used in previous studies of pure NI generated under laboratory conditions.…”

“…The modern negative ion air purifier (NIAP) technology, on the contrary, does not generate ozone but produce substantial amount of negative air ions. Negative ions have been credited with “mysterious” health benefits such as promoting physiological health and boosting immune systems 13,14 . A limited number of studies indeed have shown some health benefits of short‐term exposures to “pure” negative ions, when the technology was not used to remove airborne particles, in humans and animals 15‐17 …”

“…Given that a number of previous HEPA filtration interventions have been conducted in young and healthy adults to assess the effects on cardiorespiratory health outcomes, we carried out this study of a same design (ie, crossover intervention with NIAPs) in healthy college students. Compared to the previous study in children, 14,18 the present study substantially expanded outcome measures, allowing an assessment of cardiovascular risk factors that would be difficult to measure in children.…”

Individual- and Household-Level Interventions to Reduce Air Pollution Exposures and Health Risks: a Review of the Recent Literature

“…There were also no effects of IG use on measures of lung function, vascular tone, arterial stiffness, or inflammation. In a similar study of 44 children in Beijing classrooms, Dong et al [68] reported that 5 days of IG use decreased PM 2.5 and BC, improved lung function and reduced airway inflammation, but did not alter blood pressure. However, the study also found that negative ions were associated with detrimental effects on HRV.…”

An inversion model for estimating the negative air ion concentration using MODIS images of the Daxing’anling region

“…Besides, negative oxygen ions can improve people's sleep quality and blood circulation, enhance cardiopulmonary functions, aerobic metabolism, and recovery after movements, as well as cure pneumoconiosis by integrating with low load aerobic Yoga [11][12][13][14][15]. An NAI generator can eliminate particulate matters in the atmosphere while filtering and inactivating aerosolized viruses [16][17][18][19]. Therefore, an investigation of the NAI concentration is of great significance for human physical and mental health and the improvement of air quality.…”