William H. Bailey

Air ions and mood outcomes: a review and meta-analysis

BackgroundPsychological effects of air ions have been reported for more than 80 years in the media and scientific literature. This study summarizes a qualitative literature review and quantitative meta-analysis, where applicable, that examines the potential effects of exposure to negative and positive air ions on psychological measures of mood and emotional state.MethodsA structured literature review was conducted to identify human experimental studies published through August, 2012. Thirty-three studies (1957–2012) evaluating the effects of air ionization on depression, anxiety, mood states, and subjective feelings of mental well-being in humans were included. Five studies on negative ionization and depression (measured using a structured interview guide) were evaluated by level of exposure intensity (high vs. low) using meta-analysis.ResultsConsistent ionization effects were not observed for anxiety, mood, relaxation/sleep, and personal comfort. In contrast, meta-analysis results showed that negative ionization, overall, was significantly associated with lower depression ratings, with a stronger association observed at high levels of negative ion exposure (mean summary effect and 95% confidence interval (CI) following high- and low-density exposure: 14.28 (95% CI: 12.93-15.62) and 7.23 (95% CI: 2.62-11.83), respectively). The response to high-density ionization was observed in patients with seasonal or chronic depression, but an effect of low-density ionization was observed only in patients with seasonal depression. However, no relationship between the duration or frequency of ionization treatment on depression ratings was evident.ConclusionsNo consistent influence of positive or negative air ionization on anxiety, mood, relaxation, sleep, and personal comfort measures was observed. Negative air ionization was associated with lower depression scores particularly at the highest exposure level. Future research is needed to evaluate the biological plausibility of this association.

Validity of geographically modeled environmental exposure estimates

Abstract Geographic modeling is increasingly being used to estimate long-term environmental exposures in epidemiologic studies of chronic disease outcomes. However, without validation against measured environmental concentrations, personal exposure levels, or biologic doses, these models cannot be assumed a priori to be accurate. This article discusses three examples of epidemiologic associations involving exposures estimated using geographic modeling, and identifies important issues that affect geographically modeled exposure assessment in these areas. In air pollution epidemiology, geographic models of fine particulate matter levels have frequently been validated against measured environmental levels, but comparisons between ambient and personal exposure levels have shown only moderate correlations. Estimating exposure to magnetic fields by using geographically modeled distances is problematic because the error is larger at short distances, where field levels can vary substantially. Geographic models of environmental exposure to pesticides, including paraquat, have seldom been validated against environmental or personal levels, and validation studies have yielded inconsistent and typically modest results. In general, the exposure misclassification resulting from geographic models of environmental exposures can be differential and can result in bias away from the null even if non-differential. Therefore, geographic exposure models must be rigorously constructed and validated if they are to be relied upon to produce credible scientific results to inform epidemiologic research. To our knowledge, such models have not yet successfully predicted an association between an environmental exposure and a chronic disease outcome that has eventually been established as causal, and may not be capable of doing so in the absence of thorough validation.

Magnetic Field Exposures in the Electric Utility Industry Relevant to Occupational Guideline Levels

Abstract Several organizations have promulgated guidelines for occupational exposure to extremely low frequency magnetic fields. This article analyzes electric utility magnetic field occupational exposure data sets in order to characterize the types of workers, tasks, and environments that are associated with exposure at or near the guideline levels. The frequency and duration of magnetic field exposure of utility workers were examined for five data sets containing over 7000 workdays of measurements. Four of the data sets were from general surveys of worker exposure and the fifth was from a study of workers performing transmission and distribution live-line tasks. For job categories specific to the electric utility industry, exposure above 0.05 millitesla (mT) generally occurred during less than 1.0 percent of time at work and exposure above 0.2 mT generally occurred during less than 0.1 percent of work time. Although most periods of exposure above these magnetic field levels were brief, some lasted sever...

Air ions and respiratory function outcomes: a comprehensive review

BackgroundFrom a mechanistic or physical perspective there is no basis to suspect that electric charges on clusters of air molecules (air ions) would have beneficial or deleterious effects on respiratory function. Yet, there is a large lay and scientific literature spanning 80 years that asserts exposure to air ions affects the respiratory system and has other biological effects.AimsThis review evaluates the scientific evidence in published human experimental studies regarding the effects of exposure to air ions on respiratory performance and symptoms.MethodsWe identified 23 studies (published 1933–1993) that met our inclusion criteria. Relevant data pertaining to study population characteristics, study design, experimental methods, statistical techniques, and study results were assessed. Where relevant, random effects meta-analysis models were utilized to quantify similar exposure and outcome groupings.ResultsThe included studies examined the therapeutic benefits of exposure to negative air ions on respiratory outcomes, such as ventilatory function and asthmatic symptoms. Study specific sample sizes ranged between 7 and 23, and studies varied considerably by subject characteristics (e.g., infants with asthma, adults with emphysema), experimental method, outcomes measured (e.g., subjective symptoms, sensitivity, clinical pulmonary function), analytical design, and statistical reporting.ConclusionsDespite numerous experimental and analytical differences across studies, the literature does not clearly support a beneficial role in exposure to negative air ions and respiratory function or asthmatic symptom alleviation. Further, collectively, the human experimental studies do not indicate a significant detrimental effect of exposure to positive air ions on respiratory measures. Exposure to negative or positive air ions does not appear to play an appreciable role in respiratory function.

Biological effects of exposure to static electric fields in humans and vertebrates: a systematic review

BackgroundHigh-voltage direct current (HVDC) lines are the technology of choice for the transport of large amounts of energy over long distances. The operation of these lines produces static electric fields (EF), but the data reviewed in previous assessments were not sufficient to assess the need for any environmental limit. The aim of this systematic review was to update the current state of research and to evaluate biological effects of static EF.MethodsUsing the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) recommendations, we collected and evaluated experimental and epidemiological studies examining biological effects of exposure to static EF in humans (n = 8) and vertebrates (n = 40).ResultsThere is good evidence that humans and animals are able to perceive the presence of static EF at sufficiently high levels. Hair movements caused by electrostatic forces may play a major role in this perception. A large number of studies reported responses of animals (e.g., altered metabolic, immunologic or developmental parameters) to a broad range of static EF strengths as well, but these responses are likely secondary physiological responses to sensory stimulation. Furthermore, the quality of many of the studies reporting physiological responses is poor, which raises concerns about confounding.ConclusionThe weight of the evidence from the literature reviewed did not indicate that static EF have adverse biological effects in humans or animals. The evidence strongly supported the role of superficial sensory stimulation of hair and skin as the basis for perception of the field, as well as reported indirect behavioral and physiological responses. Physical considerations also preclude any direct effect of static EF on internal physiology, and reports that some physiological processes are affected in minor ways may be explained by other factors. While this literature does not support a level of concern about biological effects of exposure to static EF, the conditions that affect thresholds for human detection and possible annoyance at suprathreshold levels should be investigated.

Electromagnetic interference and exposure from household wireless networks

In the last few years, the use of wireless technology for household products has greatly increased, led by applications such as smart meters, Internet connected TVs, and Bluetooth links to home theater systems. In the coming years, it is almost certain that wireless technology will have a nearly ubiquitous presence in households through a variety of mundane household appliances, toys, and other consumer products. Yet, with this technology comes an increased perception of risk by end-users fueled by concerns about cancer and other health effects as well as concern about potential interference with life-saving products such as medical devices. This paper discusses concepts of radio frequency exposure and electromagnetic interference as they relate to the wireless communication networks that are likely to be used in household environments.

Measurements of Charged Aerosols Near

Current methods that assess the charge on aerosols downwind of transmission lines are not capable of determining the net charge per aerosol. A new method was used to measure the charge on aerosols upwind and downwind of two dc transmission lines in 38 measurement sessions and on aerosols in urban, suburban, and rural environments near Chicago, IL and Winnipeg, MB, Canada, in another 22 measurement sessions. The prevalence of charged aerosols around the dc lines and other environments was similar. Both upwind and downwind of the dc lines and in other environments, the distribution of the aerosol charge is bimodal, and the modal charge is one charge per aerosol. Downwind of the dc lines, the percent of aerosols with positive charge is reduced and the percent of aerosols with negative charge is increased. Despite this shift, the modal charge did not change and almost all aerosols carried fewer than 10 charges.

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Background The construction of high‐voltage direct current (HVDC) lines for the long‐distance transport of energy is becoming increasingly popular. This has raised public concern about potential environmental impacts of the static electric fields (EF) produced under and near HVDC power lines. As the second part of a comprehensive literature analysis, the aim of this systematic review was to assess the effects of static EF exposure on biological functions in invertebrates and plants and to provide the basis for an environmental impact assessment of such exposures. Methods The Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA) was used to guide the methodological conduct and reporting. Results Thirty‐three studies – 14 invertebrate and 19 plant studies – met the eligibility criteria and were included in this review. The reported behavioral responses of insects and planarians upon exposure strongly suggest that invertebrates are able to perceive the presence of a static EF. Many other studies reported effects on physiological functions that were expressed as, for example, altered metabolic activity or delayed reproductive and developmental stages in invertebrates. In plants, leaf damage, alterations in germination rates, growth and yield, or variations in the concentration of essential elements, for example, have been reported. However, these physiological responses and changes in plant morphology appear to be secondary to surface stimulation by the static EF or caused by concomitant parameters of the electrostatic environment. Furthermore, all of the included studies suffered from methodological flaws, which lowered credibility in the results. Conclusion At field levels encountered from natural sources or HVDC lines (< 35 kV/m), the available data provide reliable evidence that static EF can trigger behavioral responses in invertebrates, but they do not provide evidence for adverse effects of static EF on other biological functions in invertebrates and plants. At far higher field levels (> 35 kV/m), adverse effects on physiology and morphology, presumably caused by corona‐action, appear to be more likely. Higher quality studies are needed to unravel the role of air ions, ozone, nitric oxide and corona current on alterations in physiological functions and morphology. HighlightsEnvironmental impacts of static EF were assessed in invertebrate and plant studies.Invertebrates are able to perceive the presence of static EF near HVDC power lines.No evidence for adverse effects on physiological functions at HVDC field levels.Corona‐action appears to cause adverse biological effects at very high field levels.Methodological flaws in all reviewed studies lowered credibility in the results.

500-kV DC Transmission Lines and in Other Environments

IARC evaluation of ELF magnetic fields: Public understanding of the 0.4- μ T exposure metric

Systematic review of biological effects of exposure to static electric fields. Part II: Invertebrates and plants

BackgroundAir ions are molecules of air that have become ionized—that is, they have either lost or gained an electrical charge. Past speculation has suggested that exposure to positive air ions may be harmful to one’s health, while exposure to negative air ions may be associated with beneficial health effects. Air ions arise from natural sources as well as direct-current transmission lines and commercial ionizers. Several recent clinical studies have suggested therapeutic effects of air ions on various types of depression at exposure levels 10- to 1000-fold higher than most previous human studies. The aim of this study was to assess the evidence from studies of laboratory animals for beneficial or adverse effects of air ions on health.MethodsSixty-two studies (1935–2015) in nine topics areas were evaluated for quality and potential systematic bias by ARRIVE guidelines. Standardized mean differences or proportional differences between exposed and control groups were computed for 44 studies to quantitatively assess the strength of the evidence for exposure-related effects.ResultsMany of the studies were conducted before 1990 and exhibited various reporting and methodological deficiencies, including small sample size, failure to control for the influence of potential confounding variables, lack of randomized assignment to treatment groups and blinded analyses, and statistical errors relating to treating group-exposed animals as individuals. The highest quality studies consistently reported no effects of exposure on any of the endpoints examined. There were no evident dose–response relationships within or across studies.ConclusionsExperimental studies of laboratory animals exposed to positive and negative air ions for minutes to years over a five-log unit range of intensities did not suggest any consistent or reliable effects on measures of behavior, learning and memory, neurotransmitters, tracheal function, respiratory infection, cardiovascular function, reproduction and growth, carcinogenesis, or other health endpoints. These data do not provide evidence of adverse or beneficial effects of air ion exposure on health, and did not suggest any biological mechanism of interaction, except perhaps for mechanosensory stimulation of body surfaces by static electric fields at high air ion concentrations.