Effectiveness of air purifier on health outcomes and indoor particles in homes of children with allergic diseases in Fresno, California: A pilot study

Enhancing indoor air quality and cardiopulmonary health in patients with asthma by photocatalytic oxidation and filters air cleaner

BACKGROUND

Air purifiers can enhance indoor air quality and health outcomes, and studies have primarily focused on filters and particulate matter (PM) in households. Photocatalytic oxidation (PCO) is a promising technique for eliminating gaseous pollutants and bioaerosols. However, no field study was conducted in household. Therefore, this study evaluated the effects of the PCO and PCO + filters intervention on indoor air pollutants and cardiopulmonary endpoints in households.

METHODS

A randomized, double-blind crossover clinical trial was conducted. Indoor air pollutants, including PM, bioaerosols, and gaseous pollutants and cardiopulmonary endpoints including lung function, fractional exhaled nitric oxide (FeNO), respiratory symptoms, and blood pressure were assessed before and after intervention.

FINDINGS

This was the first study to evaluate the effects of PCO and PCO + filters interventions on indoor air pollutants and cardiopulmonary health in households. Indoor total volatile organic compounds (TVOC) and sulfur dioxides (SO2) significantly reduced after PCO intervention, however, we also observed the significant reduction in percentage of predicted values of forced vital capacity (FVC%) and forced expiratory volume in 3 s (FEV3%) and increased in FeNO after 13 days of PCO intervention. The PCO + filters intervention significantly reduced the levels of indoor PM1, PM2.5, PM4, PM10, total suspended particulate matter, ultrafine particles, airborne bacteria, fungi, endotoxin, mites, TVOC, nitrogen dioxide, and SO2, and marginal reduction in carbon monoxide. However, indoor carbon dioxide significantly increased after PCO/PCO + filters intervention. As for cardiopulmonary health, FVC%, and FEV1 % marginally increased 7 days after the PCO + filters intervention.

Indoor/Outdoor airborne microbiome characteristics in residential areas across four seasons and its indoor purification

Bioaerosols are more likely to accumulate in the residential environment, and long-term inhalation may lead to a variety of diseases and allergies. Here, we studied the distribution, influencing factors and diffusion characteristics of indoor and outdoor microbiota pollution in six residential buildings in Guangzhou, southern China over a period of one year. The results showed that the particle sizes of bioaerosol were mainly in the range of inhalable particle size (<4.7 μm) with a small difference among four seasons (74.61 % ± 2.17 %). The microbial communities showed obvious seasonal differences with high abundance in summer, but no obvious geographical differences. Among them, the bacteria were more abundant than the fungi. The dominant microbes in indoor and outdoor environments were similar, with Anoxybacillu, Brevibacillus and Acinetobacter as the dominant bacteria, and Cladosporium, Penicillium and Alternaria as the dominant fungi. The airborne microbiomes were more sensitive to temperature and particulate matter (PM2.5, PM10) concentrations. Based on the Sloan neutral model, bacteria were more prone to random diffusion than fungi, and the airborne microbiome can be randomly distributed in indoor and outdoor environments and between the two environments in each season. Bioaerosol in indoor was mainly from outdoor. The health risk evaluation showed that the indoor inhalation risks were higher than those outdoor. The air purifier had a better removal efficiency on 1.1-4.7 μm microorganisms, and the removal efficiency on Gram-negative bacteria was better than that on Gram-positive bacteria. This study is of great significance for the risk assessment and control of residential indoor bioaerosol exposure.

Feasibility of residential air quality monitoring to address asthma outcomes

Improving asthma outcomes for underserved populations can be addressed through interventions to improve indoor air quality (IAQ). New protocol for measuring IAQ and health outcomes are imperative given advances in IAQ monitoring technology and challenges in conducting intervention research in homes. In this pilot study HEPA air purifiers and HEPA vacuum cleaners were provided to five homes with children with asthma. For 6 weeks, eight common components of air quality were measured using a low-cost multi-channel air quality monitoring device, with data conveyed directly from participant homes via Wi-Fi connection. In conjunction with periodic surveys on asthma control, impact of asthma on quality of life and intervention compliance, outcomes compared IAQ, home characteristics, and asthma-related measures. This pilot study demonstrates the feasibility of a protocol to evaluate a dual component intervention to improve IAQ in homes, as measured with a low-cost air quality monitoring device.

Bronchiolitis recovery and the use of High Efficiency Particulate Air (HEPA) Filters (The BREATHE Study): study protocol for a multi-center, parallel, double-blind, randomized controlled clinical trial

BACKGROUND

Acute viral bronchiolitis is the most common reason for hospitalization of infants in the USA. Infants hospitalized for bronchiolitis are at high risk for recurrent respiratory symptoms and wheeze in the subsequent year, and longer-term adverse respiratory outcomes such as persistent childhood asthma. There are no effective secondary prevention strategies. Multiple factors, including air pollutant exposure, contribute to risk of adverse respiratory outcomes in these infants. Improvement in indoor air quality following hospitalization for bronchiolitis may be a prevention opportunity to reduce symptom burden. Use of stand-alone high efficiency particulate air (HEPA) filtration units is a simple method to reduce particulate matter ≤ 2.5 µm in diameter (PM2.5), a common component of household air pollution that is strongly linked to health effects.

METHODS

BREATHE is a multi-center, parallel, double-blind, randomized controlled clinical trial. Two hundred twenty-eight children < 12 months of age hospitalized for the first time with bronchiolitis will participate. Children will be randomized 1:1 to receive a 24-week home intervention with filtration units containing HEPA and carbon filters (in the child's sleep space and a common room) or to a control group with units that do not contain HEPA and carbon filters. The primary objective is to determine if use of HEPA filtration units reduces respiratory symptom burden for 24 weeks compared to use of control units. Secondary objectives are to assess the efficacy of the HEPA intervention relative to control on (1) number of unscheduled healthcare visits for respiratory complaints, (2) child quality of life, and (3) average PM2.5 levels in the home.

DISCUSSION

We propose to test the use of HEPA filtration to improve indoor air quality as a strategy to reduce post-bronchiolitis respiratory symptom burden in at-risk infants with severe bronchiolitis. If the intervention proves successful, this trial will support use of HEPA filtration for children with bronchiolitis to reduce respiratory symptom burden following hospitalization.

TRIAL REGISTRATION

NCT05615870. Registered on November 14, 2022.

A systematic review and meta-analysis of field studies of portable air cleaners: Performance, user behavior, and by-product emissions

Indoor air quality is important for the health of building occupants, and public interest in controlling indoor airborne pathogens increased dramatically with the COVID-19 pandemic. Pollutant concentrations can be controlled locally using portable air cleaners (sometimes called air purifiers), which allow occupants to apply air cleaning technology to meet their needs in the location and times that they find appropriate. This paper provides a systematic review of scientific literature that describes field studies of the effectiveness of portable air cleaners. Over 500 papers were considered, and 148 were reviewed in detail, to extract 35 specific research results (e.g., particulate removal performance) or characteristics (e.g., type of building). These were aggregated to provide an overview of results and approaches to this type of research, and to provide meta-analyses of the results. The review includes: descriptions of the geographical location of the research; rate of publications over time; types of buildings and occupants in the field study; types of air cleaner technology being tested; pollutants being measured; resulting pollutant removal effectiveness; patterns of usage and potential barriers to usage by occupants; and the potential for by-product emissions in some air cleaner technologies. An example result is that 83 of the 148 papers measured reductions in fine particulates (PM2.5) and found a mean reduction of 49 % with standard deviation of 20 %. The aggregated results were approximately normally distributed, ranging from finding no significant reduction up to a maximum above 90 % reduction. Sixteen of the 148 papers considered gaseous pollutants, such as volatile organic compounds, nitrogen dioxide, and ozone; 36 papers considered biological pollutants, such as bacteria, viruses, pollen, fungi, etc. An important challenge, common to several studies, is that occupants run the air cleaners for shorter periods and on low airflow rate settings, because of concerns about noise, drafts, and electricity cost, which significantly reduces air cleaning effectiveness.

Clinical Medicine and Climate Change

The health care system contributes substantially to global greenhouse gas emissions, a driver of climate change. At the same time, climate change has caused disruptions in health care delivery. In this article, the authors describe both how the health care industry contributes to climate change and how climate change affects patient care. The authors also provide clinical recommendations for health care practitioners to counsel patients on health effects of climate change and underscore the need for developing the workforce needed to respond to unique health care delivery challenges resulting from climate-related factors.

Protocol for the air purification for eosinophilic COPD study (APECS): a randomised controlled trial of home air filtration by HEPA

INTRODUCTION

Exposure to particulate matter (PM) pollution has been associated with lower lung function in adults with chronic obstructive pulmonary disease (COPD). Patients with eosinophilic COPD have been found to have higher levels of airway inflammation, greater responsiveness to anti-inflammatory steroid inhalers and a greater lung function response to PM pollution exposure compared with those with lower eosinophil levels. This study will evaluate if reducing home PM exposure by high-efficiency particulate air (HEPA) air filtration improves respiratory health in eosinophilic COPD.

METHODS AND ANALYSIS

The Air Purification for Eosinophilic COPD Study (APECS) is a double-blinded randomised placebo-controlled trial that will enrol 160 participants with eosinophilic COPD living in the area of Boston, Massachusetts. Real and sham air purifiers will be placed in the bedroom and living rooms of the participants in the intervention and control group, respectively, for 12 months. The primary trial outcome will be the change in forced expiratory volume in 1 s (FEV1). Lung function will be assessed twice preintervention and three times during the intervention phase (at 7 days, 6 months and 12 months postrandomisation). Secondary trial outcomes include changes in (1) health status by St. George's Respiratory Questionnaire; (2) respiratory symptoms by Breathlessness, Cough and Sputum Scale (BCSS); and (3) 6-Minute Walk Test (6MWT). Inflammatory mediators were measured in the nasal epithelial lining fluid (NELF). Indoor PM will be measured in the home for the week preceding each study visit. The data will be analysed to contrast changes in outcomes in the intervention and control groups using a repeated measures framework.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Institutional Review Board of Beth Israel Deaconess Medical Centre (protocol #2019P0001129). The results of the APECS trial will be presented at scientific conferences and published in peer-reviewed journals.

TRIAL REGISTRATION

NCT04252235. Version: October 2023.

Effectiveness of filtering or decontaminating air to reduce or prevent respiratory infections: A systematic review

Installation of technologies to remove or deactivate respiratory pathogens from indoor air is a plausible non-pharmaceutical infectious disease control strategy.

OBJECTIVE

We undertook a systematic review of worldwide observational and experimental studies, published 1970-2022, to synthesise evidence about the effectiveness of suitable indoor air treatment technologies to prevent respiratory or gastrointestinal infections.

METHODS

We searched for data about infection and symptom outcomes for persons who spent minimum 20 h/week in shared indoor spaces subjected to air treatment strategies hypothesised to change risk of respiratory or gastrointestinal infections or symptoms.

RESULTS

Pooled data from 32 included studies suggested no net benefits of air treatment technologies for symptom severity or symptom presence, in absence of confirmed infection. Infection incidence was lower in three cohort studies for persons exposed to high efficiency particulate air filtration (RR 0.4, 95%CI 0.28-0.58, p < 0.001) and in one cohort study that combined ionisers with electrostatic nano filtration (RR 0.08, 95%CI 0.01-0.60, p = 0.01); other types of air treatment technologies and air treatment in other study designs were not strongly linked to fewer infections. The infection outcome data exhibited strong publication bias.

CONCLUSIONS

Although environmental and surface samples are reduced after air treatment by several air treatment strategies, especially germicidal lights and high efficiency particulate air filtration, robust evidence has yet to emerge that these technologies are effective at reducing respiratory or gastrointestinal infections in real world settings. Data from several randomised trials have yet to report and will be welcome to the evidence base.

Health-based strategies for overcoming barriers to climate change adaptation and mitigation

Climate change poses an unequivocal threat to the respiratory health of current and future generations. Human activities-largely through the release of greenhouse gases-are driving rising global temperatures. Without a concerted effort to mitigate greenhouse gas emissions or adapt to the effects of a changing climate, each increment of warming increases the risk of climate hazards (eg, heat waves, floods, and droughts) that that can adversely affect allergy and immunologic diseases. For instance, wildfires, which release large quantities of particulate matter with a diameter of less than 2.5 μm (an air pollutant), occur with greater intensity, frequency, and duration in a hotter climate. This increases the risk of associated respiratory outcomes such as allergy and asthma. Fortunately, many mitigation and adaptation strategies can be applied to limit the impacts of global warming. Adaptation strategies, ranging from promotions of behavioral changes to infrastructural improvements, have been effectively deployed to increase resilience and alleviate adverse health effects. Mitigation strategies aimed at reducing greenhouse gas emissions can not only address the problem at the source but also provide numerous direct health cobenefits. Although it is possible to limit the impacts of climate change, urgent and sustained action must be taken now. The health and scientific community can play a key role in promoting and implementing climate action to ensure a more sustainable and healthy future.

Place-Based Strategies Addressing Neighborhood Environments to Improve Perinatal and Preterm Infant Outcomes

Preterm birth (defined as birth <37 weeks of gestation) is a significant health concern globally, with lasting implications for individuals, families, and society. In the United States, high preterm birth rates among Black and low-income populations likely result from differences in environmental exposures. Structural racism and economic disadvantage have led to unequal distribution of polluting industrial sites and roadways across society as well as differential access to health-promoting resources which contribute to preterm birth risk. Once born, preterm infants remain at risk for numerous environmentally responsive adverse health outcomes that affect growth and development throughout childhood and adulthood. In this commentary, we describe associations of neighborhood environments with pregnancy and preterm infant health outcomes and propose strategies to address harmful exposures that affect families across the lifespan.

Can individual protective measures safeguard cardiopulmonary health from air pollution? A systematic review and meta-analysis

Evidence supporting the effect of individual protective measures (IPMs) on air pollution is relatively scarce. In this study, we performed a systematic review and meta-analysis to investigate the effects of air purifiers, air-purifying respirators, and cookstove changes on cardiopulmonary health outcomes. We searched PubMed, Scopus, and Web of Science until December 31, 2022, 90 articles and 39,760 participants were included. Two authors independently searched and selected the studies, extracted information, and assessed each study's quality and risk of bias. We performed meta-analyses when three or more studies were available for each IPMs, with comparable intervention and health outcome. Systematic review showed that IPMs were beneficial in children and elderly with asthma along with healthy individuals. Meta-analysis results showed a reduction in cardiopulmonary inflammation using air purifiers than in control groups (with sham/no filter) with a decrease in interleukin 6 by -0.247 μg/mL (95% confidence intervals [CI] = -0.413, -0.082). A sub-group analysis for air purifier as an IPMs in developing counties reduced fractional exhaled nitric oxide by -0.208 ppb (95% confidence intervals [CI] = -0.394, -0.022). However, evidence describing the effects of air purifying respirator and cook stove changes on cardiopulmonary outcomes remained insufficient. Therefore, air purifiers can serve as efficient IPMs against air pollution. The beneficial effect of air purifiers is likely to have a greater effect in developing countries than in developed countries.

The efficacy of the Dyson air purifier on asthma control: A single-center, investigator-led, randomized, double-blind, placebo-controlled trial

BACKGROUND

Air pollution is associated with poor asthma outcomes. High-efficiency particulate air air purifiers may reduce air pollution and thus improve asthma outcomes. However, the efficacy of such devices for this purpose remains inconclusive.

OBJECTIVE

To investigate the effects of reducing the levels of pollutants on asthma outcomes in adults, using a novel Dyson high-efficiency particulate air air purifier.

METHODS

In a single-center, double-blinded, randomized controlled trial, participants (N = 50) were randomized at a 1:1 ratio to active filters (intervention) or to dummy filters (placebo) for a total of 78 weeks. The primary outcomes were the changes in Asthma Control Questionnaire 6 (ACQ6) and Asthma-specific Quality of Life Questionnaire (AQLQ) scores from baseline. The secondary outcomes were changes in indoor air pollution and lung function measurements. The coronavirus disease 2019 pandemic limited spirometry measurements to 2 time points and assessment of fractional exhaled nitric oxide and bronchial hyperresponsiveness to baseline only.

RESULTS

Air pollutant levels were significantly lower in the intervention group compared with the placebo group (P = .0003). Both groups had a significant improvement in their ACQ6 and AQLQ. However, there were no significant between-group differences in ACQ6, AQLQ, or spirometry, compared with baseline in multivariable repeated measures models.

CONCLUSION

The Dyson air purifier significantly improved air quality. However, there were no significant improvements in asthma control, quality of life, or measures of lung function in the intervention group compared with the control group despite improvements in indoor air quality. Larger, extended studies are required to confirm or refute these findings, especially given that the coronavirus disease 2019 pandemic prevented the procurement of detailed objective data.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04729530; ttps://clinicaltrials.gov/ct2/show/NCT04729530.

Changes in heart rate variability of healthy subjects shortly exposed to printing shop particles and the effect of air purifier intervention

Particulate matter (PM) released by printers may cause airway inflammation and cardiac electrophysiological changes. We conducted a two-stage crossover study to examine the association between short-term exposure to printing shop particles (PSPs) and the heart rate variability (HRV) among healthy volunteers, as well as to evaluate the effect of air purifier intervention. The on-site assessments of PSPs and individual HRV parameters of the volunteers were used to analyze the influence of size-fractionated PSPs and air purifier intervention on HRV at different lag times after PSPs exposure (0 min, 5 min, 15 min, and 30 min) by using the linear mixed-effects models. We observed that changes in 6 HRV parameters were associated with particle mass concentration (PMC) of PSPs, and changes in 8 HRV parameters were associated with particle number concentration (PNC) of PSPs. The sensitive HRV parameters were the square root of the mean of the sum of the squares of differences between adjacent NN intervals (rMSSD), NN50 count divided by the total number of all NN intervals (pNN50), normalized high frequency power (nHF), very high frequency power (VHF), normalized low frequency power (nLF), and the ratio of low frequency power to high frequency power (LF/HF). Most HRV parameters exhibited the strongest effect associated with PMC and PNC at a lag time of 30 min. The air purifier intervention markedly reduced the PNC and PMC of size-fractionated PSPs, enhanced 5 HRV parameters, and decreased the nLF and LF/HF. Our study suggests that short-term exposure to PSPs can affect HRV parameters, reflecting changes in cardiac autonomic nervous activity, and the use of an air purifier can reduce the concentration of PSPs and improve the autonomic nervous system activity of the exposed individuals.

Experimental and numerical analysis of indoor air quality affected by outdoor air particulate levels (PM1.0, PM2.5 and PM10), room infiltration rate, and occupants' behaviour

This study conducted an experimental analysis of how indoor air quality (IAQ) is influenced by the outdoor air pollutants levels, infiltration rate, and occupants' behaviours. The impacts of these factors on IAQ were analyzed using on-site measurements and numerical simulations. The results contribute to a better understanding of how to control the Indoor Particulate Level (IPL) for the specific conditions of the studied building. Results showed that occupant behaviour was the primary factor in determining the IPL, significantly changing the number of outdoor particles introduced to the building. Moreover, it was found that the IPL was exponentially correlated to the Outdoor Particulate Level (OPL). Based on numerical simulations, this study concluded that smaller particles do not always have more chance than larger particles of accessing the indoor environment through the building envelope. Meanwhile, a steady-state indoor particle concentration numerical model was established and verified using the 4-fold cross-validation method. Finally, simulation results identified that the room infiltration rate had a positive linear impact on IAQ if the OPL was under 30 μg/m³. This is because the increased air exchange rate can help to dilute indoor air pollutants when the outdoor air is relatively clean.

Lung Effects of Household Air Pollution

Biomass fuel smoke, secondhand smoke, and oxides of nitrogen are common causes of household air pollution (HAP). Almost 2.4 billion people worldwide use solid fuels for cooking and heating, mostly in low- and middle-income countries. Wood combustion for household heating is also common in many areas of high-income countries, and minorities are particularly vulnerable. HAP in low- and middle-income countries is associated with asthma, acute respiratory tract infections in adults and children, chronic obstructive pulmonary disease, lung cancer, tuberculosis, and respiratory mortality. Although wood smoke exposure levels in high-income countries are typically lower than in lower-income countries, it is similarly associated with accelerated lung function decline, higher prevalence of airflow obstruction and chronic bronchitis, and higher all-cause and respiratory cause-specific mortality. Household air cleaners with high-efficiency particle filters have mixed effects on asthma and chronic obstructive pulmonary disease outcomes. Biomass fuel interventions in low-income countries include adding chimneys to cookstoves, improving biomass fuel combustion stoves, and switching fuel to liquid petroleum gas. Still, the impact on health outcomes is inconsistent. In high-income countries, strategies for reducing biomass fuel-related HAP are centered on community-level woodstove changeout programs, although the results are again inconsistent. In addition, initiatives to encourage home smoking bans have mixed success in households with children. Environmental solutions to reduce HAP have varying success in reducing pollutants and health problems. Improved understanding of indoor air quality factors and actions that prevent degradation or improve polluted indoor air may lead to enhanced environmental health policies, but health outcomes must be rigorously examined.

Indoor Air Purification and Residents' Self-Rated Health: Evidence from the China Health and Nutrition Survey

Indoor air pollution is injurious to human health, even worse than outdoor air pollution. However, there is a lack of empirical evidence using large samples in developing countries regarding whether indoor air purification can improve human health by reducing indoor air pollutants. Using the data from the China Health and Nutrition Survey in 2015, this study analyzes the relationship between indoor air purification and residents' self-rated health. We apply the generalized ordered logit model and find that indoor air purification has a significantly positive effect on residents' self-rated health. This positive effect is limited to improving the probability of residents' health level being rated "good", and there is no significant movement between the two levels of "bad" and "fair". The results also show that, as an important source of indoor air pollutants, solid fuels used in cooking significantly reduced residents' self-rated health level. Additional results show the heterogeneity of the relationship between indoor air purification and resident health among groups with different characteristics. This study provides empirical evidence for further optimizing the indoor air environment.

Long-term evaluation of a low-cost air sensor network for monitoring indoor and outdoor air quality at the community scale

Given the growing interest in community air quality monitoring using low-cost sensors, 30 PurpleAir II sensors (12 outdoor and 18 indoor) were deployed in partnership with community members living adjacent to a major interstate freeway from December 2017- June 2019. Established quality assurance/quality control techniques for data processing were used and sensor data quality was evaluated by calculating data completeness and summarizing PM_2.5 measurements. To evaluate outdoor sensor performance, correlation coefficients (r) and coefficients of divergence (CoD) were used to assess temporal and spatial variability of PM_2.5 between sensors. PM_2.5 concentrations were also compared to traffic levels to assess the sensors' ability to detect traffic pollution. To evaluate indoor sensors, indoor/outdoor (I/O) ratios during resident-reported activities were calculated and compared, and a linear mixed-effects regression model was developed to quantify the impacts of ambient air quality, microclimatic factors, and indoor human activities on indoor PM_2.5. In general, indoor sensors performed more reliably than outdoor sensors (completeness: 73% versus 54%). All outdoor sensors were highly temporally correlated (r > 0.98) and spatially homogeneous (CoD<0.06). The observed I/O ratios were consistent with existing literature, and the mixed-effects model explains >85% of the variation in indoor PM_2.5 levels, indicating that indoor sensors detected PM_2.5 from various sources. Overall, this study finds that community-maintained sensors can effectively monitor PM_2.5, with main data quality concerns resulting from outdoor sensor data incompleteness.

Substantial health benefits of strengthening guidelines on indoor fine particulate matter in China

In 2020, China for the first time developed guidelines for indoor fine particulate matter (PM_2.5) in the draft document of indoor air standards, while the associated health implication remains unclear. Here, we first estimated the PM_2.5 associated premature deaths was 965 thousand in 2019, with the indoor PM_2.5 of outdoor origin accounting for 72.9%. Then, we examined the dynamic mortalities under a scenario matrix of 36 conditions, by incorporating various shared socioeconomic pathways in 2035, the draft guidelines and the contributions of ambient PM_2.5 to indoor exposure. Although it may be improbable, the averages of premature deaths associated with ambient PM_2.5 will be 1018-1361 thousand in 2035 when the worst-case scenario of guidelines mandating a yearly (rather than daily) indoor PM_2.5 concentration of 75 µg/m³, compared to the averages of estimation were 816-1304 thousand for better-case scenario of 35 µg/m³. Under these scenarios, the increase in the number of premature deaths was mainly driven by population aging. In 2035, an ambitious target of yearly indoor PM_2.5 concentrations of 15 µg/m³ is anticipated to reduce the number of deaths associated with ambient PM_2.5 by approximately 25% of the 2019 baseline. Stricter guidelines to restrict the indoor PM_2.5 concentrations are recommended to mitigate the mortality risk in the future.

Personal Interventions to Reduce Exposure to Outdoor Air Pollution

Unhealthy levels of air pollution are breathed by billions of people worldwide, and air pollution is the leading environmental cause of death and disability globally. Efforts to reduce air pollution at its many sources have had limited success, and in many areas of the world, poor air quality continues to worsen. Personal interventions to reduce exposure to air pollution include avoiding sources, staying indoors, filtering indoor air, using face masks, and limiting physical activity when and where air pollution levels are elevated. The effectiveness of these interventions varies widely with circumstances and conditions of use. Compared with upstream reduction or control of emissions, personal interventions place burdens and risk of adverse unintended consequences on individuals. We review evidence regarding the balance of benefits and potential harms of personal interventions for reducing exposure to outdoor air pollution, which merit careful consideration before making public health recommendations with regard to who should use personal interventions and where, when, and how they should be used. Expected final online publication date for the Annual Review of Public Health, Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Reducing particulates in indoor air can improve the circulation and cardiorespiratory health of old people: A randomized, double-blind crossover trial of air filtration

Exposure to indoor air particulate pollution increases respiratory and cardiovascular morbidity and mortality, especially in the elderly. To assess a short-term, indoor air filtration's potential benefit on circulatory and cardiopulmonary health among healthy older people, a randomized, double-blind crossover trial was conducted with 24 healthy residents of an aged-care center in Chongqing, China in 2020. Each room received a high-efficiency particulate air filter air purifier and a placebo air purifier for two days. Fifteen circulatory system biomarkers of inflammation, coagulation, and oxidative stress; lung function; blood pressure (BP); heart rate (HR) and fractional exhaled nitric oxide (FeNO) were measured end of each two days. Indoor air particulate pollution was monitored throughout the study period. Linear mixed-effect models were used to associate health outcome variables with indoor particles. This intervention study demonstrated that air filtration was associated with significantly decreased concentrations of inflammatory and coagulation biomarkers, but not of biomarkers of oxidative stress and lung function. Just 48 h of air filtration can improve the cardiopulmonary health of the elderly. Air purifiers may be a public health measure that can be taken to improve circulatory and cardiopulmonary health among older people.

A review on reducing indoor particulate matter concentrations from personal-level air filtration intervention under real-world exposure situations

Improving air quality in indoor environments where people live is of importance to protect human health. In this systematic review, we assessed the effectiveness of personal-level use of air filtration units in reducing indoor particulate matters (PM) concentrations under real-world situations following systematic review guidelines. A total of 54 articles were included in the review, in which 20 randomized controlled/crossover trials that reported the changes in indoor fine PM (PM_2.5 ) concentrations were quantitatively assessed in meta-analysis. Standardized mean differences (SMDs) were calculated for changes in indoor PM concentrations following air filtration interventions. Moderate-to-large reductions of 11%-82% in indoor PM_2.5  concentrations were observed with SMD of -1.19 (95% CI: -1.50, -0.88). The reductions in indoor PM concentrations varied by geographical locations, filtration technology employed, indoor environmental characteristics, and air pollution sources. Most studies were graded with low-to-moderate risk of bias; however, the overall certainty of evidence for indoor PM concentration reductions was graded at very low level. Considering the effectiveness of indoor air filtration under practical uses, socio-economic disparities across study populations, and costs of air filter replacement over time, our results highlight the importance of reducing air pollution exposure at the sources.

Assessing effectiveness of air purifiers (HEPA) for controlling indoor particulate pollution

The present study deals with an evaluation of the air purifier's effectiveness in reducing the concentration of different sized particulate matter (PM) and ions in the real-world indoor environment. Two types of air purifiers (API and APII) mainly equipped with High-Efficiency Particulate Air (HEPA) filters that differed in other specifications were employed in general indoor air and the presence of an external source (candles and incense). The gravimetric sampling of PM was carried out by SKC Cascade Impactor and further samples were analyzed for determining ions' concentration while real-time monitoring of different sized PM was done through Grimm Aerosol Spectrometer (1.109). The result showed that API reduced PM levels of different sizes ranged from 12-52% and 29–53% in general indoor air and presence of external source respectively. Concerning the APII, a higher decrease percent in PM level was explored in presence of an external source (52–68%) as compared to scenarios of general indoor air (37–64%). The concentrations of the ions were noticed to be decreased in all three size fractions but surprisingly some ions' (not specific) concentrations increased on the operation of both types of air purifiers. Overall, the study recommends the use of air purifiers with mechanical filters (HEPA) instead of those which release ions for air purification.

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Efficiency of air purifier (AP) in removing indoor air pollutants was observed.

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AP was more effective on small-sized particles than large ones.

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AP of large Clean Air Delivery Rate removed particulate and ions more effectively.

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APs with mechanical filters must be employed instead of ions generators.

The Effect of Particulate Matter Reduction by Indoor Air Filter Use on Respiratory Symptoms and Lung Function: A Systematic Review and Meta-analysis

PURPOSE

Exposure to particulate matter (PM) is a key public health issue, but effective intervention has not yet been established. A systematic literature review and meta-analysis has been conducted to assess the relationship between the use of air filters, one of the most commonly studied interventions, and respiratory outcomes in patients with chronic respiratory diseases.

METHODS

We systematically reviewed intervention studies on PM using PubMed, EMBASE, and Cochrane databases up to September 2019. Studies that included data on PM concentration changes and respiratory symptoms or lung function in patients with respiratory diseases were eligible for inclusion. Effect estimates were quantified separately using the random-effects model.

RESULTS

Six studies were included in the quantitative analysis. Air filter use reduced indoor PM2.5 by 11.45 µg/m³ (95% confidence interval [CI], 6.88, 16.01 µg/m³). Air filter use was not associated with improvements in respiratory symptoms in 5 of the 6 studies or significant changes in the predicted forced expiratory volume in one second (FEV1) (mean change, -1.77%; 95% CI, -8.25%, 4.71%). Air filter use was associated with improved peak expiratory flow rate by 5.86 (95% CI, 3.5, 8.19 of standardized difference).

CONCLUSIONS

The findings of this systematic review suggest that air filters may reduce indoor PM and increase peak expiratory rate in asthmatic patients. However, most studies showed no significant effects of air filters on respiratory symptoms or FEV1. Further studies in regions with high-density PM may provide additional information on this issue.

TRIAL REGISTRATION

PROSPERO Identifier: CRD42020156258.

Portable air purification: Review of impacts on indoor air quality and health

A systematic literature review was carried out to examine the impact of portable air purifiers (PAPs) on indoor air quality (PM_2.5) and health, focussing on adults and children in indoor environments (homes, schools and offices). Analysed studies all showed reductions in PM_2.5 of between 22.6 and 92.0% with the use of PAPs when compared to the control. Associations with health impacts found included those on blood pressure, respiratory parameters and pregnancy outcomes. Changes in clinical biochemical markers were also identified. However, evidence for such associations was limited and inconsistent. Health benefits from a reduction in PM_2.5 would be expected as the cumulative body of scientific evidence from various cohort studies shows positive impacts of long-term reduction in PM_2.5 concentrations. The current evidence demonstrates that using a PAP results in short-term reductions in PM_2.5 in the indoor environment, which has the potential to offer health benefits.

Nrf2 modulated the restriction of lung function via impairment of intrinsic autophagy upon real-ambient PM2.5 exposure

Compelling studies approve that fine particle matter (PM_2.5) exposure was associated with high risk of respiratory disorders. However, the available data assessing the detailed influence of PM_2.5 on lung was limited. To overcome the difficulty of inhalational PM_2.5 exposure, the real-ambient PM_2.5 exposure system was constructed. The mice were exposed to filtered air (FA) or real-ambient PM_2.5 (PM_2.5), and the adverse effect on lung was determined. Nuclear factor E2-related factor 2 (Nrf2) as a transcription factor, was reported to affect autophagy. Autophagy was proposed as a two-edge sword in respiratory disorders. Here, our data presented that PM_2.5 exposure dramatically reduced the lung function of WT mice rather than Nrf2^-/- mice. Consistently, thickened alveolar walls was observed in WT mice in PM_2.5 exposure group, whereas the histological phenotype of Nrf2^-/- mice exhibited no obvious alteration. Furthermore, PM_2.5 exposure triggered low-grade production of inflammatory profile in WT and Nrf2^-/- mice. Moreover, the protein levels of p62, Beclin1 and LC3B of WT mice rather than Nrf2^-/- mice were also altered in PM_2.5 exposure group. Taken together, the present study applied the real-ambient exposure system, revealed the adverse effect of air pollution on lung, and proposed the underlying mechanism.

Air pollution and indoor settings

Indoor environments contribute significantly to total human exposure to air pollutants, as people spend most of their time indoors. Household air pollution (HAP) resulting from cooking with polluting ("dirty") fuels, which include coal, kerosene, and biomass (wood, charcoal, crop residues, and animal manure) is a global environmental health problem. Indoor pollutants are gases, particulates, toxins, and microorganisms among others, that can have an impact especially on the health of children and adults through a combination of different mechanisms on oxidative stress and gene activation, epigenetic, cellular, and immunological systems. Air pollution is a major risk factor and contributor to morbidity and mortality from major chronic diseases. Children are significantly affected by the impact of the environment due to biological immaturity, prenatal and postnatal lung development. Poor air quality has been related to an increased prevalence of clinical manifestations of allergic asthma and rhinitis. Health professionals should increase their role in managing the exposure of children and adults to air pollution with better methods of care, prevention, and collective action. Interventions to reduce household pollutants may promote health and can be achieved with education, community, and health professional involvement.

Individual and population level protection from particulate matter exposure by wearing facemasks

Because of the severe air pollution in northern China, facemasks have gained popularity in this area in recent years. Although the results of previous studies have shown the effectiveness of wearing facemasks for intercepting particles, the individual differences and the overall health benefits of wearing facemasks have not been comprehensively documented. In this study, using both model and personal tests under various conditions, we test eight major brands of facemasks for their removal efficiencies (REs) of particulate matter (PM) in six size ranges (from 0.3 μm to >10 μm). The results are used to assess the overall exposure reduction at the individual and population levels in Beijing. We find significant differences in REs among PM sizes, facemask brands, pollution levels, and genders. Combining the information on the usage of various brands, facemask wearing rates, and PM_2.5 concentrations in the ambient and indoor air in this area, we evaluate the overall effect of facemask wearing on PM_2.5 exposure reduction. It is quantitatively demonstrated that because people spend most time indoors, facemask protection is limited. For facemask wearers, the overall exposure can be reduced by less than 20%, whereas the reduction rate is as low as 2.4 ± 1.6% for the entire adult populations even in the year with the highest level of pollution with an annual mean PM_2.5 concentration of 102 ± 98 μg∙m^-3. As a strategy of self-protection from long-term exposure to particulate matter, wearing facemasks outdoors is inferior to the installation of indoor air purifiers.

Association between Peak Expiratory Flow Rate and Exposure Level to Indoor PM2.5 in Asthmatic Children, Using Data from the Escort Intervention Study

Various studies have indicated that particulate matter <2.5 μm (PM2.5) could cause adverse health effects on pulmonary functions in susceptible groups, especially asthmatic children. Although the impact of ambient PM2.5 on children’s lower respiratory health has been well-established, information regarding the associations between indoor PM2.5 levels and respiratory symptoms in asthmatic children is relatively limited. This randomized, crossover intervention study was conducted among 26 asthmatic children’s homes located in Incheon metropolitan city, Korea. We aimed to evaluate the effects of indoor PM2.5 on children’s peak expiratory flow rate (PEFR), with a daily intervention of air purifiers with filter on, compared with those groups with filter off. Children aged between 6–12 years diagnosed with asthma were enrolled and randomly allocated into two groups. During a crossover intervention period of seven weeks, we observed that, in the filter-on group, indoor PM2.5 levels significantly decreased by up to 43%. (p < 0.001). We also found that the daily or weekly unit (1 μg/m³) increase in indoor PM2.5 levels could significantly decrease PEFR by 0.2% (95% confidence interval (CI) = 0.1 to 0.5) or PEFR by 1.2% (95% CI = 0.1 to 2.7) in asthmatic children, respectively. The use of in-home air filtration could be considered as an intervention strategy for indoor air quality control in asthmatic children’s homes.

Health Benefits of Air Pollution Reduction

Air pollution is a grave risk to human health that affects nearly everyone in the world and nearly every organ in the body. Fortunately, it is largely a preventable risk. Reducing pollution at its source can have a rapid and substantial impact on health. Within a few weeks, respiratory and irritation symptoms, such as shortness of breath, cough, phlegm, and sore throat, disappear; school absenteeism, clinic visits, hospitalizations, premature births, cardiovascular illness and death, and all-cause mortality decrease significantly. The interventions are cost-effective. Reducing factors causing air pollution and climate change have strong cobenefits. Although regions with high air pollution have the greatest potential for health benefits, health improvements continue to be associated with pollution decreases even below international standards. The large response to and short time needed for benefits of these interventions emphasize the urgency of improving global air quality and the importance of increasing efforts to reduce pollution at local levels.

Indoor air filtration could lead to increased airborne endotoxin levels

Stand-alone portable air purifiers (APs) have become an increasingly popular method of controlling individual inhalation exposure. Exposure to bacterial endotoxins has a causative role in respiratory inhalation health. Here, we studied the changes in endotoxin levels in indoor air before and after purification by a portable AP equipped with HEPA (high-efficiency particulate air) filters. An increase in endotoxins was observed when a previously used AP was turned on to clean the air. Replacing the HEPA filters in the AP helped to mitigate the increase in endotoxins of larger sizes but not endotoxins of smaller sizes. Consequently, the use of APs could lead to increased endotoxin deposition in airways, especially in the alveolar region. The endotoxin concentrations on the HEPA filters were well correlated with the free DNA concentrations on the HEPA filters. This correlation indicates that the disrupted bacteria, which released free DNA, could also release endotoxins, thus making HEPA filters a source of indoor airborne endotoxins. Our results illustrate a potential endotoxin inhalation risk associated with HEPA-APs as an air cleaning strategy and highlight the importance of composition-specific air cleaning while reducing the particle number/mass.

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

Few studies have investigated household interventions to enhance indoor air quality (IAQ) and health outcomes in relatively low-income communities. This study aims to examine the impact of the combined intervention with asthma education and air purifier on IAQ and health outcomes in the US-Mexico border area. An intervention study conducted in McAllen, Texas, between June and November 2019 included 16 households having children with asthma. The particulate matter (PM2.5) levels were monitored in the bedroom, kitchen, and living room to measure the IAQ for 7 days before and after the intervention, respectively. Multiple surveys were applied to evaluate changes in children's health outcomes. The mean PM2.5 levels in each place were significantly improved. Overall, they significantly decreased by 1.91 μg/m3 on average (p < 0.05). All surveys showed better health outcomes; particularly, quality of life for children was significantly improved (p < 0.05). This pilot study suggests that the combined household intervention might improve IAQ in households and health outcomes for children with asthma and reduce health disparities in low-income communities. Future large-scale studies are needed to verify the effectiveness of this household intervention to improve IAQ and asthma management.

Effects of Air Purifiers on Patients with Allergic Rhinitis: a Multicenter, Randomized, Double-Blind, and Placebo-Controlled Study

PURPOSE

Exposure to particulate matter (PM) is a well-known risk factor in the triggering and exacerbation of allergic airway disease. Indoor environments, where people spend most of their time, are of utmost importance. To assess the effects of air purifiers [equipped with high-efficiency particulate air (HEPA) filters] on allergic rhinitis (AR) in adult patients, we performed a multicenter, randomized, double-blind, and placebo-controlled study.

MATERIALS AND METHODS

Patients with house dust mite (HDM)-induced AR were randomly assigned to either active or mockup (placebo) air-purification groups. Two air purifiers (placed in living room and bedroom) were operated for 6 weeks in each home environment. The primary study endpoint was to achieve improvement in AR symptoms and medication scores. Secondary endpoints were to achieve improvement in the quality of life (QoL) and visual analog scale (VAS) scores, as well as in the indoor (bedroom and living room) concentrations of PM_2.5 and PM₁₀.

RESULTS

After 6 weeks of air purifier use, medication scores improved significantly in the active (vs. placebo) group, although subjective measures (symptoms, VAS, and QoL scores) did not differ. Bedroom PM_2.5 concentrations initially exceeded living room or outdoor levels, but declined (by up to 51.8%) following active purifier operation. Concentrations of PM_2.5 in living room and PM₁₀ in bedroom and living room were also significantly reduced through active purification.

CONCLUSION

The use of air purifiers with HEPA filters significantly reduced medication requirements for patients with HDM-induced AR and significantly lowered indoor PM_2.5 concentrations, regardless of room placement. Active intervention to reduce household air pollutants may help improve allergic airway disease (clinicaltrials.gov NCT03313453).

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

Importance

Fine particles (particulate matter 2.5 μm [PM2.5]), 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 PM2.5 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 PM2.5-removing device in the bedrooms of children with asthma.

Design, Setting, and Participants

Children 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 PM2.5 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 PM2.5 concentrations were moderately high, ranging from 28.6 to 69.8 μg/m3 (median, 53 μg/m3). During true filtration, bedroom PM2.5 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 PM2.5 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 PM2.5 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.

Trial Registration

ClinicalTrials.gov Identifier: NCT03282864.

Personal strategies to minimise effects of air pollution on respiratory health: advice for providers, patients and the public

As global awareness of air pollution rises, so does the imperative to provide evidence-based recommendations for strategies to mitigate its impact. While public policy has a central role in reducing air pollution, exposure can also be reduced by personal choices. Qualified evidence supports limiting physical exertion outdoors on high air pollution days and near air pollution sources, reducing near-roadway exposure while commuting, utilising air quality alert systems to plan activities, and wearing facemasks in prescribed circumstances. Other strategies include avoiding cooking with solid fuels, ventilating and isolating cooking areas, and using portable air cleaners fitted with high-efficiency particulate air filters. We detail recommendations to assist providers and public health officials when advising patients and the public regarding personal-level strategies to mitigate risk imposed by air pollution, while recognising that well-designed prospective studies are urgently needed to better establish and validate interventions that benefit respiratory health in this context.

Effects of the Use of Air Purifier on Indoor Environment and Respiratory System among Healthy Adults

Air purifiers have become popular among ordinary families. However, it remains controversial whether indoor air purification improves the respiratory health of healthy adults. A randomized crossover intervention study was conducted with 32 healthy individuals. The subjects were categorized into two groups. One group continuously used true air purifiers, and the other followed with sham air purifiers for 4 weeks. Following this first intervention, all the subjects underwent a 4-week washout period and continued with the second 4-week intervention with the alternate air purifiers. We collected fine particulate matter (PM) ≤ 2.5 µm in aerodynamic diameter (PM2.5), coarse particulate matter between 2.5 and 10 µm in aerodynamic diameter (PM10–2.5) and ozone (O₃). The subjects’ pulmonary function and fractional exhaled nitric oxide (FeNO) were measured during the study period. The indoor PM2.5 concentrations decreased by 11% with the true air purifiers compared to those with sham air purifiers. However, this decrease was not significant (p = 0.08). The air purification did not significantly improve the pulmonary function of the study subjects. In contrast, an increase in the indoor PM10–2.5 and O₃ concentration led to a significant decrease in the forced expiratory volume in one second (FEV_1.0)/forced vital capacity (FVC) and maximal mid-expiratory flow (MMEF), respectively. In conclusion, air purification slightly improved the indoor PM2.5 concentrations in ordinary homes but had no demonstrable impact on improving health.

Evaluation of the effectiveness of a portable air cleaner in mitigating indoor human exposure to cooking-derived airborne particles

Gas cooking is an important source of airborne particulate matter (PM) indoors. Exposure to cooking-derived PM can lead to adverse human health impacts on non-smokers, especially in poorly-ventilated residential homes. Most of the previous studies on gas cooking emissions mainly focused on fine particles (PM_2.5) with little information on their size-fractionation. Moreover, studies dealing with mitigation of indoor human exposure to cooking-derived PM are currently sparse. Therefore, a systematic study was conducted to investigate the characteristics of PM_2.5 and size-fractionated PM derived from five commonly used cooking methods, namely, steaming, boiling, stir-frying, pan-frying and deep-frying in a poorly-ventilated domestic kitchen under controlled experimental conditions. Additionally, an indoor portable air cleaner was employed as a mitigation device to capture cooking-derived PM and improve indoor air quality (IAQ). Results revealed that the oil-based deep-frying cooking released the highest airborne particles which were about 170 folds higher compared to the baseline levels for PM_2.5 mass concentrations. The use of the air cleaner showed a statistically significant (p < 0.05) reduction in the indoor PM_2.5 levels. Moreover, PM_<0.25 (particles with diameter ≤ 250 nm) showed a very high mass concentration (378.2 μg/m³) during deep-frying, raising human health concern. A substantial reduction (~60-85%) in PM_<0.25 mass concentrations and their total respiratory deposition doses (RDD) in the human respiratory tract was observed while using the air cleaner during the five cooking methods. Furthermore, morphological characteristics and the relative abundance of trace elements in cooking-derived PM were also investigated. This study provides useful insights into the assessment and mitigation of indoor human exposure to cooking-derived PM.

Effects of Indoor Air Purifiers on Children with Asthma

PURPOSE

To evaluate the effects of air purifiers on the concentrations of indoor air pollutants and on asthma control in children.

MATERIALS AND METHODS

In this randomized crossover trial, daily use of an air purifier filter was compared with a matched placebo with the filter off. Thirty elementary school students who had asthma were enrolled and randomly allocated to one of two groups. The primary endpoints were changes in indoor air quality, asthma severity, lung function, airway inflammatory, urine microbiome, and phthalate after the installation of air purifiers. PM_2.5 and CO₂ were measured as indoor air pollutants. Asthma severity was assessed in terms of both symptom and medication scores acquired using a daily questionnaire. The higher the score, the better the symptom or the less frequent the use of medication. Peak expiratory flow rate and fractional exhaled nitric oxide were also measured.

RESULTS

The mean age of the enrolled patients was 9.2±1.98 years. The mean concentration of PM_2.5 was 17.0 μg/m³ in the filter-off condition, but significantly lower at 9.26 μg/m³ in the filter-on condition. Medication scores were 6.9 for the filter-off and 7.12 for the filter-on conditions, reflecting a statistically significant decrease in the frequency of medications used during air purifier operation. Bacterial richness, as determined using the Chao 1 index, was markedly lower in the filter-on than the filter-off condition.

CONCLUSION

This study suggests that air purifiers benefit medication burden in children with asthma by reducing PM_2.5 levels.

Environmental Factors as Modulators of the Relationship between Obstructive Sleep Apnea and Lesions in the Circulatory System

Obstructive sleep apnea (OSA) is a growing social problem, particularly in well-developed countries. It has been demonstrated that obstructive sleep apnea is a significant risk factor for cardiovascular diseases, including arterial hypertension, ischemic heart disease, heart failure, rhythm/conduction disturbances, as well as cerebral stroke. The pathophysiology of these diseases is complex and multifactorial. We present the current state of research on behavioral and environmental factors that influence the relationship between OSA and cardiovascular changes. We discuss the relationship between obesity, alcohol, sedatives, environmental tobacco smoke, allergic diseases and environmental pollution on the one hand and OSA on the other. In this context, the environment should be considered as an important modulator of the relationship between OSA and cardiovascular diseases.

Fine Particulate Matter (PM2.5) is a Risk Factor for Dermatitis by Promoting the Expression of Thymic Stromal Lymphopoietin (TSLP) in Keratinocytes

Aim:

Common indoor pollutants, as fine particulate matter (PM2.5), can damage people's health and cause skin allergies. However, it remains unknown which common pollutants can lead to allergy, such as, in children atopic dermatitis, and what is the key molecule. This study aimed to investigate the thymic stromal lymphopoietin (TSLP) produced from keratinocytes after environmental pollutant stimulation.

Methods:

PAM212 cells were treated by several pollutants, including PM2.5, formaldehyde, m-xylene, and 1,2,4-trimethylbenzene, and tried to analyze their relationships. The mRNA expression level of TSLP was determined by qPCR. The protein level of TSLP was detected by ELISA analysis.

Results:

The mRNA expression of TSLP was significantly up-regulated when PAM212 cells were stimulated by PM2.5 at 25 μg/ml for 12 h. Meanwhile, the protein level of TSLP in culture supernatant was increased. However, TSLP protein production was not detected in culture supernatant treated with formaldehyde, m-xylene, and 1, 2, 4-trimethylbenzene.

Conclusion:

PM2.5 promotes the expression of TSLP and may aggravate allergic response using this pathway.

HEPA filtration improves asthma control in children exposed to traffic-related airborne particles

Traffic-related airborne particles are associated with asthma morbidity. The aim of this study was to assess the impact of a high-efficiency particulate air (HEPA) filtration on the concentrations of traffic particles and the resultant effect on children with asthma. Forty-three children with asthma were enrolled in this double-blind, placebo-controlled crossover design. A HEPA air cleaner or a placebo "dummy" was placed in participants' homes for four weeks, interrupted by a one-month washout period, before crossing over to the other treatment arm for four weeks. Air sampling and health outcomes, including asthma control (ACQ) and quality of life (AQLQ) measures, were completed prior to and at the end of each treatment arm. Indoor concentrations of traffic particles were significantly reduced with the HEPA treatment but not with the "dummy" treatment. In participants with poorly controlled asthma and lower quality of life at baseline, ACQ and AQLQ scores were significantly improved (1.3 to 0.9, P = .003 and 4.9 to 5.5, P = .02, respectively) following the HEPA treatment. In this study, HEPA filtration is associated with improved clinical outcomes and quality of life measures in children with uncontrolled asthma.

The severity of lung injury and metabolic disorders induced by ambient PM2.5 exposure is associated with cumulative dose

Lots of epidemiological and experimental studies have found that ambient fine particulate matter (PM_2.5) exposure is associated with the development of cardiopulmonary diseases, obesity and diabetes. This study focused on the effects of cumulative PM_2.5 exposure on pulmonary and systemic inflammation and insulin resistance. Thirty-two 6-week-old male Balb/c mice were randomly divided into four groups (FA, PM, WEEK and DAY groups) and were continuously or intermittently exposed to concentrated PM_2.5 or filtered air (FA) for four weeks using Shanghai Meteorological and Environmental Animal Exposure System ("Shanghai-METAS"). The levels of IL-6 and TNF-α in serum, bronchoalveolar lavage fluid (BALF), lung tissues and white adipose tissue (WAT) were measured. Meanwhile, the expression of NF-κB and phosphor-NF-κB in lung tissue was detected by Western blot. Glucose tolerance and insulin resistance were also determined at the end of exposure. The results found that the mice in PM group displayed moderate inflammatory cell infiltration in lung, whereas the mice in WEEK and DAY groups displayed slight inflammatory cell infiltration in lung. Compared with the mice in FA group, the mRNA expressions of IL-6 and TNF-α in lung tissue and WAT significantly increased in the mice of PM group. Importantly, IL-6 and TNF-α mRNA expressions in PM group were higher than those in WEEK and DAY groups. The protein expression of phospho-NF-κB in lung tissue showed that PM group showed the activation of NF-κB, which was higher than that in the WEEK and DAY groups. Meanwhile, the mice in PM group showed more severe glucose tolerance and insulin resistance than that in the WEEK and DAY groups. The results suggested that the reduction of PM_2.5 cumulative exposure may alleviate pulmonary and adipose inflammation, insulin resistance and glucose tolerance impairment. The results provided a clue that the interruption of ambient PM_2.5 exposures by systems such as indoor air purification could be of benefit to people's health.

Effectiveness of Using Enhanced Filters in Schools and Homes to Reduce Indoor Exposures to PM2.5 from Outdoor Sources and Subsequent Health Benefits for Children with Asthma

Filters can reduce indoor concentrations of particulate matter (PM_2.5), but their benefits have not been well-characterized. This study investigates exposure, health, and cost impacts of high efficiency filters in homes and schools, focusing on the asthma-related outcomes. Reductions in indoor exposures to PM_2.5 from outdoor sources with enhanced filters (e.g., MERV 12) are estimated using probabilistic indoor air quality models, and avoided health impacts are quantified using health impact assessment. These methods are applied using data from Detroit, Michigan, an urban region with elevated asthma rates. Replacing inefficient filters with enhanced filters in schools would reduce the PM_2.5-attributable asthma burden by 13% annually, with higher benefits for more efficient filters. Marginal costs average $63 per classroom or $32 per child with asthma per year. In homes, using efficient furnace filters or air cleaners yields 11 to 16% reductions in the asthma burden with an annualized marginal costs of $151-494 per household. Additional benefits include reductions in health risk for adults and lower exposures to other contaminants such as PM from indoor sources. On the basis of the included health outcomes, efficient filters in schools in particular is a potentially cost-efficient way to reduce the asthma-related health burden for children.