Effects on eyes and nose in humans after experimental exposure to airborne office dust

The environment and dry eye-manifestations, mechanisms, and more

Dry eye disease (DED) is a multifactorial condition that often presents with chronic symptoms of pain (that can be characterized as "dryness," "burning," and "irritation," to name a few) and/or fluctuating or poor-quality vision. Given its multifactorial nature, several pathophysiologic mechanisms have been identified that can underlie symptoms, including tear film, ocular surface, and/or corneal somatosensory nerve abnormalities. Research has focused on understanding how environmental exposures can increase the risk for DED flares and negatively impact the tear film, the ocular surface, and/or nerve health. Given that DED is a common condition that negatively impacts physical and mental functioning, managing DED requires multiple strategies. These can include both medical approaches and modulating adverse environmental conditions, the latter of which may be a cost-effective way to avoid DED flares. Thus, an understanding of how environmental exposures relate to disease is important. This Review summarizes research on the relationships between environmental exposures and DED, in the hope that this information will engage healthcare professionals and patients to consider environmental manipulations in their management of DED.

Corrosion Inhibition and Disinfection of Heating and Cooling Water Systems Using In Situ Generated Hydrogen Peroxide

Aqueous solutions of MnCl2·4H2O and Tiron (disodium 4,5-dihydroxy-1,3-benzenedisulfonate) rapidly remove dioxygen (O2) from aqueous solution at a rate of ~20 mg∙ L -1 min-1 with turnover frequencies (TOFs) of up...

Impact of Air Pollution and Weather on Dry Eye

Air pollution has broad effects on human health involving many organ systems. The ocular surface is an excellent model with which to study the effects of air pollution on human health as it is in constant contact with the environment, and it is directly accessible, facilitating disease monitoring. Effects of air pollutants on the ocular surface typically manifest as dry eye (DE) symptoms and signs. In this review, we break down air pollution into particulate matter (organic and inorganic) and gaseous compounds and summarize the literature regarding effects of various exposures on DE. Additionally, we examine the effects of weather (relative humidity, temperature) on DE symptoms and signs. To do so, we conducted a PubMed search using key terms to summarize the existing literature on the effects of air pollution and weather on DE. While we tried to focus on the effect of specific exposures on specific aspects of DE, environmental conditions are often studied concomitantly, and thus, there are unavoidable interactions between our variables of interest. Overall, we found that air pollution and weather conditions have differential adverse effects on DE symptoms and signs. We discuss these findings and potential mitigation strategies, such as air purifiers, air humidifiers, and plants, that may be instituted as treatments at an individual level to address environmental contributors to DE.

Study of the neurotoxicity of indoor airborne nanoparticles based on a 3D human blood-brain barrier chip

BACKGROUND

There is growing public awareness regarding the health effects of indoor nanoscale particulate matter (INPM) since people spend the majority of their time indoors. INPM could have a direct entry route into the brain via the axons of the olfactory nerve and migrating across the blood-brain barrier (BBB). Using animals to explore this possibility is not a reliable method to fully demonstrate human physiological responses. We, therefore, set out to develop a human 3D functional blood-brain barrier model to examine the potential effects of INPM on the cerebral nervous system.

METHODS

Human astrocytes were co-cultured and human umbilical vein endothelial cells in 3D within a microfluidic chip to simulate the micro-complex physiological structure of the human BBB. This 3D human organotypic model has then been made to investigate any INPM-induced BBB dysfunction linked to potential cellular responses.

RESULTS

A 3D human functional blood-brain barrier was constructed in this study. We observed the translocation of INPM across the blood-brain barrier. The 3D human organotypic chip initially reflected damage to the nervous system with abnormal astrocyte proliferation and a decline in cell viability. We also looked at the behavior of oxidative stress-related biomarkers (ROS, GSH-Px, and MDA). INPM was implicated in aggravating inflammation via reactive oxygen species (ROS). The Keap1-Nrf2-ARE pathway is a key mechanism in cellular resistance to oxidative stress by mediating and activating a variety of antioxidant and detoxification enzymes. Following ROS accumulation, INPM induced abnormal expression of nuclear transcription factor Nrf2. This behavior disturbed the expression of, γ-glutamate synthase (γ-GCS) and heme oxygenase (HO-1), which further exacerbated the imbalance of the antioxidant system.

CONCLUSIONS

This functional 3D human organotypic chip effectively mimics the physiological response of the human BBB. The chip provides a micro-complex structure to simulate the internal environment of the human blood-brain barrier, and partially simulates the physiological responses of the BBB to INPM exposure. Based on this model, INPM was shown to affect the blood-brain barrier biofunction by disrupting the Keap1-Nrf2-ARE pathways.

Eyelid Disorders in Ophthalmology Practice: Results from a Large International Epidemiological Study in Eleven Countries

Purpose

Anecdotal evidence suggests that eyelid disorders are common, although estimates of prevalence vary. The current study determines the prevalence of eyelid disorders, meibomian gland dysfunction (MGD) and related diseases (specifically ocular surface disease) in a population of patients presenting for routine ophthalmologic consultations.

Methods

This cross-sectional epidemiologic survey evaluated patients presenting for routine ophthalmic visits. During the consultation an ophthalmologist completed a questionnaire, and each patient underwent an ophthalmic examination and completed a quality of life questionnaire.

Results

Three hundred forty-nine ophthalmologists, recruited from 11 countries, provided data on 6525 patients. Patients were predominantly females (61.6%). The mean age of the study population was 57.0 ± 17.6 years. Eyelid disorders were diagnosed in 5109 (78.3%) patients and were statistically associated with: atopic dermatitis, seborrheic dermatitis, dry eye, age-related macular degeneration, diabetes, cataract, allergy and MGD (P < 0.05, all associations). Eyelid abnormalities were identified in 59.6% of patients; conjunctival or corneal abnormalities were observed in 64.9% and 28.1% of patients, respectively. MGD was diagnosed in 54.3% patients and was statistically significantly associated with the presence of eyelid disorders and eyelid margin abnormalities (P < 0.001, both comparisons). Dry eye was diagnosed in 61.8% of patients. Concurrent dry eye and MGD were present in 67.6% of patients. Most patients reported some degree of impaired vision and daily/work activities related to dry eye. Impact on contact lens usage, emotions and quality of sleep was also reported. The effects on daily life were associated with the presence of MGD.

Conclusion

In conclusion, eyelid disorders were highly prevalent in this ‘real-world’ population of patients from ophthalmology clinics. Routine ophthalmologic consultations provide an opportunity to improve patient quality of life and to modify topical therapy in patients who may be predisposed to eyelid disorders.

Relationships Between Short-Term Exposure to an Indoor Environment and Dry Eye (DE) Symptoms

Air composition influences Dry Eye (DE) symptoms as demonstrated by studies that have linked the outdoor environment to DE. However, there is insufficient data on the effect of short-term exposure to indoor environments on DE symptoms. We conducted a prospective experimental research, in which an older building served as an experimental site, and a newer building served as the control site. Indoor air quality was monitored in both buildings. One-hundred-and-ninety-four randomly selected individuals were interviewed in the afternoon exiting the buildings and de-identified responses were recorded. Self-reported DE symptoms were modeled with respect to experimental and control buildings, adjusting for potential confounders. The experimental site had 2-fold higher concentration of airborne particulate matter (24,436 vs. 12,213 ≥ 0.5 µm/ft3) and microbial colonies (1066 vs. 400/m3), as compared to the control building. DE symptoms were reported by 37.5% of individuals exiting the experimental and 28.4% exiting the control building. In the univariate analysis, subjects exiting the experimental building were 2.21× more likely to report worsening of DE symptoms since morning compared to the control building (p < 0.05). When adjusting for confounders, including a history of eye allergy, subjects from the experimental building were 13.3× more likely to report worsening of their DE symptoms (p < 0.05). Our findings suggest that short-term exposure to adverse indoor environmental conditions, specifically air pollution and bioaerosols, has an acutely negative impact on DE symptoms.

Psychosocial perception of the effects of harmattan dust on the environment and health of building occupants in Maiduguri, Nigeria

Purpose

The purpose of this paper is to investigate the psychosocial perception of harmattan dust on building openings, health and housekeeping to determine the influence of the dust on building occupants.

Design/methodology/approach

Population-representative survey data were collected from Maiduguri, Northeastern Nigeria, through physical administration of questionnaires by assessing several variables. Statistical package SPSS 16.0 was used for the data analysis, which is mainly descriptive analysis in frequencies, percentages and means together with a repeated Pearson’s chi-square analysis to identify the relationship between the factors and the significance testing.

Findings

The results show that majority (94.3%) experienced dust problem in harmattan season, and a larger part (76.6%) confirmed that the dust penetrates through doors and windows. Higher percentage (91.2%) noticed that the dust particles on their floor/furniture surfaces, and on an average, people clean their houses three times daily in harmattan season. Majority (80.5%) of the respondents smell dust in the harmattan season, and greater part (77.9%) experienced health challenges in this season, of which 12.8% confirmed harmattan dust aggravates their asthma, 13.6% confirmed it causes headache, 3.1% confirmed it exacerbated pneumonia, 58.5% confirmed it causes coughing, 3.5% confirmed catarrh, 2.3% confirmed nasal/respiratory congestion, sneezing and bronchitis and 6.2% experienced eye problems. Moreover, the results indicate that number/types of openings in a building are significantly associated with factors including smelling dust in the harmattan season and health problem experienced because of dust indoors. The number of times people clean their homes/workplaces is significantly related to important variables such as experiencing dust problem in harmattan season and number/type of openings in a building. The results further established that the health problem experienced by people is significantly related to important variables including dust problem experienced in the harmattan season and type of openings in a room.

Originality/value

Harmattan dust is a serious challenge to health and well-being of building occupants in the study area. The built environment professionals need to optimize building openings for effective dust control indoors.

A Murine Model of Acute Allergic Conjunctivitis Induced by Continuous Exposure to Particulate Matter 2.5

Purpose

Several pieces of epidemiologic evidence have indicated PM2.5 (particulate matter with a diameter of 2.5 μm or less) as a causing factor of allergic conjunctivitis, but without experimental elucidation of mechanism. In the present study, PM2.5 in solution was directly applied to the mouse ocular surface to elucidate whether PM2.5 might cause allergic conjunctivitis, and its underlying mechanisms were analyzed.

Methods

ICR mice were challenged for 18 consecutive days with eye drops containing PM2.5 at 3.2, 6.4, and 12.8 mg/mL in 0.9% NaCl saline, along with the controls prepared in parallel without PM2.5 and another control group treated with both PM2.5 at 12.8 mg/mL and artificial tears. On day 19, the whole eyes and meibomian glands were harvested for histopathological analyses and assessment of clinical scoring, tear volume, tear breakup time, and tear ferning. Furthermore, goblet cells by periodic acid Schiff stain and infiltrated eosinophils by Giemsa stain were quantified and compared among study groups.

Results

Clinical scoring showed more eyelid edema, tearing, and scratching behaviors, with longer tear breakup time under the influence of increased PM2.5 concentrations. Tear ferning assay showed less tear crystal formation and decreased crystal branches after exposure to PM2.5. In addition, higher goblet cell density in the upper palpebral conjunctiva and extensive eosinophil infiltration in the entire conjunctiva and in the meibomian glands were induced by PM2.5.

Conclusions

These results demonstrate that PM2.5 can induce symptoms similar to clinical allergic conjunctivitis and that the murine acute allergic conjunctivitis model can be induced by direct exposure to PM2.5.

The mystery of dry indoor air - An overview

"Dry air" is a major and abundant indoor air quality complaint in office-like environments. The causality of perceived "dry air" and associated respiratory effects continues to be debated, despite no clear definition of the complaint, yet, has been provided. The perception of "dry air" is semantically confusing without an associated receptor but mimics a proto-state of sensory irritation like a cooling sensation. "Dry air" may also be confused with another common indoor air quality complaint "stuffy air", which mimics the sense of no fresh air and of nasal congestion. Low indoor air humidity (IAH) was dismissed more than four decades ago as cause of "dry air" complaints, rather indoor pollutants was proposed as possible exacerbating causative agents during the cold season. Many studies, however, have shown adverse effects of low IAH and beneficial effects of elevated IAH. In this literature overview, we try to answer, "What is perceived "dry air" in indoor environments and its associated causalities. Many studies have shown that the perception is caused not only by extended exposure to low IAH, but also simultaneously with and possibly exacerbated by indoor air pollutants that aggravate the protective mucous layer in the airways and the eye tear film. Immanent diseases in the nose and airways in the general population may also contribute to the overall complaint rate and including other risk factors like age of the population, use of medication, and external factors like the local ambient humidity. Low IAH may be the single cause of perceived "dry air" in the elderly population, while certain indoor air pollutants may come into play among susceptible people, in addition to baseline contribution of nasal diseases. Thus, perceived "dry air" intercorrelates with dry eyes and throat, certain indoor air pollutants, ambient humidity, low IAH, and nasal diseases.

Water extract of indoor dust induces tight junction disruption in normal human corneal epithelial cells

In corneal epithelium, tight junctions play a vital role in its barrier function. Human cornea is highly susceptible to damage by dust. Continued daily exposure to dust has been associated with increased risks of corneal injury. Studies demonstrated that water extract of dust induced cytotoxicity in human corneal epithelial cells (HCECs); however, its effects on corneal epithelial barrier function are unknown. In this study, we determined the concentrations of heavy metals in water extracts of dust, with office dust having higher concentrations of heavy metals than housedust, and Cu and Zn being highest among metals for both dust. Changes in barrier function and its associated mechanism after exposing HCECs to water extracts of dust at 48 μg/100 μ L for 7 d were evaluated. Water extracts of both dust caused decrease of TEER value (39-73%), down-regulation of gene expression related to tight junction and mucin (0.2-0.8 fold), and loss of ZO-1 immunoreactivity from cellular borders, with office dust having greater potential than housedust to disrupt corneal epithelial barrier function. Our data implied the importance to reduce heavy metals in dust to reduce their adverse impacts on human eyes.

Impact of cleanliness on the productivity of employees

Purpose

The purpose of this paper is to investigate whether the cleanliness of a work environment has influence on the productivity of employees working in office environments of non-profit organizations in The Netherlands.

Design/methodology/approach

In the study, an online survey (including questions about the perceived cleanliness) and two objective cleanliness assessment methods (particle counts and surface cleanliness) are used. The data are collected using an online questionnaire to determine the workers’ perception (of productivity and cleanliness) and to measure the cleanliness (visual assessment of the surface cleanliness and measured [dust] particle counts in the ambient air) at five different non-profit organizations in The Netherlands.

Findings

It is found that a higher objective cleanliness correlates significantly with a higher perceived productivity of employees working in office environments of non-profit organizations in The Netherlands. A higher measured cleanliness also correlates significantly with a higher work satisfaction level of employees working in office environments. Finally, a significant correlation is found between the satisfaction of employees with their work as a whole and the perceived productivity of the employees; a higher satisfaction leads to a higher perceived productivity.

Research limitations/implications

The cleanliness is measured in five non-profit organizations, so it is not possible to draw any strong generalization. Future studies are needed to confirm or contradict the findings in this research.

Practical implications

The results highlight the aspects of the cleanliness in the office environment that influence the perceived productivity. This concerns the measured cleanliness. Employees evaluate their own productivity lower at a higher level of particle counts in the ambient air in the office environment and when more dirt and stain are found on the surface (lower surface cleanliness). In response to these findings, it is recommended to carry out regular cleaning activities in the office environment where the employees perform their work. Overall, to maintain or achieve maximum personal productivity, a clean office environment is important.

Originality/value

This research is the first to identify the relationship between perceived productivity and measured cleanliness of the office environment.

Clinical and allergological analysis of ocular manifestations of sick building syndrome

PURPOSE

The disease concept of sick building syndrome (SBS) is still unclear. Ocular mucous membrane irritation is one of the major symptoms of SBS. However, the immunological aspects of the ocular complications of SBS are not yet clarified. The clinical and allergological aspects of SBS cases with ocular disorders with special reference to allergic conjunctival diseases (ACD) were analyzed, especially with respect to local immunological features.

METHODS

Twelve cases of SBS with ocular findings and 49 cases of ACD (allergic conjunctivitis [AC], atopic keratoconjunctivitis [AKC], and vernal keratoconjunctivitis [VKC]) for comparison were evaluated. The clinical findings in SBS and ACD were scored, and tear film breakup time (BUT) was measured. Cytokine (interferon-γ [IFN-γ], interleukin [IL]-2, IL-4, IL-5, IL-6, IL-8, and IL-13) concentrations in tears were analyzed by cytometric bead arrays. Eosinophil count in peripheral blood, total IgE in serum, and multiple allergen simultaneous test (MAST) for antigen-specific IgE were also measured.

RESULTS

In SBS, conjunctival lesions were observed in all cases, and corneal abnormalities were found in two-thirds of the cases. Limbal lesions were observed in 2 pediatric cases. Mean serum total IgE level in SBS was significantly higher than that in AC; however, it was significantly lower than that in AKC and VKC. Eosinophil count in peripheral blood and number of positive allergens in MAST were significantly lower in SBS than in AKC and VKC. Significant elevation of tear IL-4 was observed in SBS and ACD. However, in contrast to ACD, elevation of other cytokines in tears was not observed in SBS. Mean tear BUT in SBS was in the normal range.

CONCLUSION

From these results, SBS is thought to be partially induced by an allergic response. However, clinical dissociation of the ocular clinical findings and local immunological features in tear cytokines may suggest that SBS belongs to a different entity from ACD.

Molecular mechanisms of dust-induced toxicity in human corneal epithelial cells: Water and organic extract of office and house dust

Human corneal epithelial (HCE) cells are continually exposed to dust in the air, which may cause corneal epithelium damage. Both water and organic soluble contaminants in dust may contribute to cytotoxicity in HCE cells, however, the associated toxicity mechanisms are not fully elucidated. In this study, indoor dust from residential houses and commercial offices in Nanjing, China was collected and the effects of organic and water soluble fraction of dust on primary HCE cells were examined. The concentrations of heavy metals in the dust and dust extracts were determined by ICP-MS and PAHs by GC-MS, with office dust having greater concentrations of heavy metals and PAHs than house dust. Based on LC50, organic extract was more toxic than water extract, and office dust was more toxic than house dust. Accordingly, the organic extracts induced more ROS, malondialdehyde, and 8-Hydroxydeoxyguanosine and higher expression of inflammatory mediators (IL-1β, IL-6, and IL-8), and AhR inducible genes (CYP1A1, and CYP1B1) than water extracts (p<0.05). Extracts of office dust presented greater suppression of superoxide dismutase and catalase activity than those of house dust. In addition, exposure to dust extracts activated NF-κB signal pathway except water extract of house dust. The results suggested that both water and organic soluble fractions of dust caused cytotoxicity, oxidative damage, inflammatory response, and activation of AhR inducible genes, with organic extracts having higher potential to induce adverse effects on primary HCE cells. The results based on primary HCE cells demonstrated the importance of reducing contaminants in indoor dust to reduce their adverse impacts on human eyes.

Mechanisms of housedust-induced toxicity in primary human corneal epithelial cells: Oxidative stress, proinflammatory response and mitochondrial dysfunction

Human cornea is highly susceptible to damage by dust. Continued daily exposure to housedust has been associated with increasing risks of corneal injury, however, the underlying mechanism has not been elucidated. In this study, a composite housedust sample was tested for its cytotoxicity on primary human corneal epithelial (PHCE) cells, which were exposed to dust at 5-320μg/100μL for 24h. PHCE cell viability showed a concentration-dependent toxic effect, attributing to elevated intracellular ROS. Moreover, when exposed at >20-80μg/100μL, dust-induced oxidative damage was evidenced by increased malondialdehyde and 8-hydroxy-2-deoxyguanosine (1.3-2.3-fold) and decreased antioxidative capacity (1.6-3.5-fold). Alteration of mRNA expression of antioxidant enzymes (SOD1, CAT, HO-1, TRXR1, GSTM1, GSTP1, and GPX1) and pro-inflammatory mediators (IL-1β, IL-6, IL-8, TNF-α, and MCP-1) were also observed. Furthermore, the mitochondrial transmembrane potential was dissipated from 9.2 to 82%. Our results suggested that dust-induced oxidative stress probably played a vital role in the cytotoxicity in PHCE cells, which may have contributed to dust-induced impairment of human cornea.

Estimation of the in vitro eye irritating and inflammatory potential of lipopolysaccharide (LPS) and dust by using reconstituted human corneal epithelium tissue cultures

CONTEXT

Eye irritation is a common complaint in indoor environment, but the causes have still not been identified among the multiple exposures in house environments. To identify the potential environmental factors responsible for eye irritation and study the possible mechanisms, an in vitro model for eye irritation is suggested.

MATERIALS AND METHODS

In this study, reconstituted human corneal epithelium (HCE) tissue cultures were used to study the eye irritating and inflammatory potential of lipopolysaccharide (LPS) and dust. HCE tissue cultures were exposed to a range of concentrations of LPS for 6 h and dust for 24 h, respectively. After exposure, viability and secretion of interleukins (IL) IL-1β, IL-8, and tumor necrosis factor (TNFα) were examined. Histology was used to indicate the morphological changes after dust exposure.

RESULTS

Both LPS and dust affected HCE viability. There was an increased level of IL-8 after LPS exposure, while the concentrations of IL-1β and TNFα remained unaffected. Dust exposure resulted in an elevation of both IL-1β and IL-8, but not TNFα. Histology study showed increased vacuolization and reduced thickness after 24 h exposure to 5 mg/mL dust.

DISCUSSION AND CONCLUSION

LPS and dust showed in vitro eye irritating and inflammatory potential, and cytokines/chemokines like IL-1β and IL-8 may be involved in the mechanisms of eye irritation. The HCE tissue culture may be used as an in vitro model to study environmental exposure induced eye irritation and inflammation.

Evaluation of the tear film instability in children with allergic diseases

CONTEXT

The presence of dry eye syndrome (DES) in ocular allergic diseases was evaluated in several studies. Despite this, little exists about the tear film instability in atopic children including patients with allergic rhinitis (AR), allergic conjunctivitis (AC) and asthma. This is a study which presents intriguing findings regarding the relationship of tear film instability with clinical aspects in atopic children.

OBJECTIVE

To determine the tear film instability in children with AR, AC and asthma.

MATERIALS AND METHODS

One hundred and thirty-five consecutive children with AR, AC and asthma as study group and 45 children without any systemic and ocular abnormality as control group were included in the study. Skin prick tests, measurement of tear film breakup time (TFBUT), serum immunoglobulin E and eosinophil counts were performed in all patients. Also four subgroups of patients were designated as AR group (Group I), AC group (Group II), asthma group (Group III) and control group (Group IV).

RESULTS

Socio-demographic characteristics were similar except for family atopy between the groups (p > 0.05). The mean TFBUT was significantly lower in the study group (15.5 ± 4.4 s) than the control group (18.4 ± 2.9 s; p = 0.000). Also, there was no significant differences in the percentage of the patients who has TFBUT<10 s (p = 0.066). In logistic regression analysis, atopy was found to be the determinant of lower TFBUT (OR = 16.33, 95%; CI = 1.17 to 228.05, p = 0.03).

CONCLUSION

The presence of tear film instability was higher in children with AC, AR and asthma. This finding should be taken in consideration in atopic children.

Is household air pollution a risk factor for eye disease?

In developing countries, household air pollution (HAP) resulting from the inefficient burning of coal and biomass (wood, charcoal, animal dung and crop residues) for cooking and heating has been linked to a number of negative health outcomes, mostly notably respiratory diseases and cancers. While ocular irritation has been associated with HAP, there are sparse data on adverse ocular outcomes that may result from acute and chronic exposures. We consider that there is suggestive evidence, and biological plausibility, to hypothesize that HAP is associated with some of the major blinding, and painful, eye conditions seen worldwide. Further research on this environmental risk factor for eye diseases is warranted.

Allergic conjunctivitis and dry eye syndrome

BACKGROUND

Allergic conjunctivitis (AC) and dry eye syndrome (DES) are 2 of the most common anterior inflammatory disorders of the ocular surface and one does not preclude the coexistence of the other.

OBJECTIVES

To examine the potential overlap between AC and DES as comorbidities.

METHODS

Using the validated questionnaire known as Subjective Evaluation of Symptom of Dryness, we studied self-reported itchiness, dryness, and redness. In an outpatient optometric setting, 689 patients treated from January 1, 2007, to January 1, 2011, were surveyed for their ocular history and categorized according to their reported level of discomfort of itchiness, dryness, and redness.

RESULTS

Patients ranged in age from 5 to 90 years (median age, 25 years; 39.5% male; 60.5% female). In the studied 689 patients, clinically significant itchiness was found in 194 (28.2%), dry eyes in 247 (35.8%), and redness in 194 (28.2%). Symptom overlap was demonstrated in many of the patients. Of the 194 patients with itchiness, 112 (57.7%) had clinically significant dryness. In the 247 patients with dry eyes, 112 (45.3%) had clinically significant itch. Redness was apparent in 120 of the 194 patients with itch (61.9%) and 122 of the 247 patients with dryness (49.4%). Statistical analysis demonstrated that self-reported itchiness, dryness, and redness were not independent of each other (P<.001; Pearson χ(2) test). The odds of patients with "itchy eyes" also experiencing dry eyes were 2.11 times and the odds of these patients also experiencing redness were 7.34 times that of patients with nonitchy eyes.

CONCLUSIONS

Most patients with "itchy eyes" consistent with AC also have dry eyes and redness. These results suggest that some symptomatic patients concomitantly have features of AC and DES.

Ocular allergy

The eye is probably the most common site for the development of allergic inflammatory disorders, because it has no mechanical barrier to prevent the impact of allergens such as pollen on its surface. Physicians in various specialties and subspecialties who provide some form of primary care frequently encounter various forms of inflammation of the anterior surface of the eye that present as "red eye." However, the eye is rarely the only target for an immediate allergic-type response. Typically, many patients have other combinations of allergic disorders, such as rhinoconjunctivitis, rhinosinusitis, asthma, urticaria, or eczema. Even so, ocular signs and symptoms can frequently be the most prominent features of the entire allergic response for which a patient visits his or her physician. An improved differential diagnosis provides the basis for improved treatment algorithms. Over the past 20 years, we have witnessed an astonishing growth in therapeutic advances, ranging essentially from derivatives of simple aspirin to various newly developed biologic immunomodulatory agents, utilizing implantable drug-delivery devices that exceed the safety and efficacy of those available for other organ systems, and resorting to advanced surgical techniques for the correction of sight-threatening, disease-related complications. Overall, with the expanding knowledge base, the intricacy of ocular inflammation appears to be becoming ever more manageable and, with the team approach between the primary care physician, the ophthalmologist, and the clinical allergist/immunologist, the new "immuno-ophthalmology" approach improves patient outcomes.

Induction of GSNO reductase but not NOS in the lungs of mice exposed to glucan-spiked dust

Both in vivo and in vitro studies have suggested that airborne organic dusts may induce inflammatory responses in the lungs, characterized by typical patterns of cytokine up-regulation and secretion. Recent work showed that exposure to glucan-spiked dust might influence nasal and pulmonary function, without an accompanying inflammatory response. However, effects of glucan-spiked dust exposure on NOS and GSNO reductase (enzymes important to NO signaling) remain less clear. This study aims to determine the effects of simultaneous exposure to glucan-spiked dust on NO signaling pathway in the airway. Danish Office dust was spiked with 1% (1-3)-β-glucan (curdlan). Mice were exposed to 20 μL PBS (controls), 20 μL 25 μg/20 μL OVA and 20 μL 100 μg/20 μL glucan-spiked dust, respectively, daily for 12 days. NOS and GSNO reductase activity were measured in lung homogenate. Glutathione concentration and SOD activity in lung tissue were also determined to evaluate changes in oxidative stress. IL-6 concentration was measured in lungs to quantify the inflammatory response. Results showed that 12 day OVA and glucan-spiked dust exposure did not significantly influence NOS activity, GSH concentration, SOD activity, or IL-6 concentration. An insignificant increase in GSNOR activity and expression was observed in 12 day OVA-exposed mice, whereas glucan-spiked dust exposure significantly increased GSNOR activity and expression. Our results suggested that repeated glucan-spiked dust exposure to the airway could activate GSNO reductase but not NOS. Since GSNO reductase plays a pivotal role in NO signaling, these results may have clinical importance.

The effect of ozonization on furniture dust: microbial content and immunotoxicity in vitro

Moisture and mold problems in buildings contaminate also the furniture and other movable property. If cleaning of the contaminated furniture is neglected, it may continue to cause problems to the occupants even after the moisture-damage repairs. The aim of this study was to determine the effectiveness of high-efficiency ozone treatment in cleaning of the furniture from moisture-damaged buildings. In addition, the effectiveness of two cleaning methods was compared. Samples were vacuumed from the padded areas before and after the treatment. The microbial flora and concentrations in the dust sample were determined by quantitative cultivation and QPCR-methods. The immunotoxic potential of the dust samples was analyzed by measuring effects on cell viability and production of inflammatory mediators in vitro. Concentrations of viable microbes decreased significantly in most of the samples after cleaning. Cleaning with combined steam wash and ozonisation was more effective method than ozonising alone, but the difference was not statistically significant. Detection of fungal species with PCR showed a slight but nonsignificant decrease in concentrations after the cleaning. The immunotoxic potential of the collected dust decreased significantly in most of the samples. However, in a small subgroup of samples, increased concentrations of microbes and immunotoxicological activity were detected. This study shows that a transportable cleaning unit with high-efficiency ozonising is in most cases effective in decreasing the concentrations of viable microbes and immunotoxicological activity of the furniture dust. However, the method does not destroy or remove all fungal material present in the dust, as detected with QPCR analysis, and in some cases the cleaning procedure may increase the microbial concentrations and immunotoxicity of the dust.

Ambient sulphur dioxide exposure and emergency department visits for migraine in Vancouver, Canada

OBJECTIVES

Ambient exposure to sulphur dioxide (SO2) has been previously associated with emergency department (ED) visits for migraine headaches. In the present study, the objective was to examine the relationship between ED visits for migraine and ambient sulphur dioxide concentrations.

DESIGN AND METHODS

This was a time-series study of 1059 ED visits for migraine (ICD-9: 346) recorded at a Vancouver hospital between 1999 and 2003 (1 520 days). Air pollution levels of SO2 were measured by fixed-site monitoring stations. The generalized linear mixed models technique was applied to regress daily counts of ED visits for migraine on the levels of the pollutant after adjusting for meteorological conditions: temperature and relative humidity. The analysis was stratified by season and gender.

RESULTS

Positive and statistically significant correlations were observed for SO2 exposure and ED visits for migraine for females during colder months (October-March). The percentage increase in daily visits was 16.8% (95% CI: 1.2-34.8) for a 4-day average (of daily mean concentrations) SO2 level, for an interquartile range (IQR) increase of 1.9 ppb.

CONCLUSIONS

Our findings provide additional support for a consistent correlation between migraine headache and air pollution (SO2).

Nasal hyperresponders and atopic subjects report different symptom intensity to air quality: a climate chamber study

Short-term exposure to dust and dust added with beta-(1,3)-d-glucan or aldehydes may cause sensory reactions. In random order, we exposed 36 volunteers in a climate chamber to clean air, office dust, dust with glucan, and dust with aldehydes. Three groups of subjects were exposed, eleven were non-atopic with nasal histamine hyperreactivity, 13 were non-atopic, and 12 were atopic. Subjective ratings of symptoms and general health were registered four times during four 6-h exposure sessions. Six symptom intensity indices were constructed. The nasal hyperreactive group had a high and time-dependent increase of mucous membrane irritations, whereas the atopic group had a low and stable rate of irritations with exposure time, close to the reference group (P = 0.02 for differences between the groups with respect to time under exposure for Weak Inflammatory Responses and P = 0.05 for Irritative Body Perception, significance mainly because of the nasal hyperreactive group). Exposure to dust, with or without glucan or aldehydes, showed increased discomfort measured by the index for Constant Indoor Climate, and dust with glucan had a similar effect for the index for Lower Respiratory Effects. For Psychological and Neurological Effects these were dependent on group affiliation, thus preventing a uniform statement of exposure effects for all three investigated groups.

PRACTICAL IMPLICATIONS

Opportunities for identifying persons with high or low sensitivity to low-level exposures are important in preventive medicine and will reduce intra-group variability and thus increase the power of experimental and epidemiological studies searching for correlations between exposures and health effects. The contrast between nasal hyperreactive on one side and atopic and reference subjects on the other side is particularly important. The atopic group indicated a non-homogenous reaction depending on their hyperreactive status, a finding that could be important but needs further confirmation.

Effects on human eyes caused by experimental exposures to office dust with and without addition of aldehydes or glucan

Thirty-six volunteers (in three susceptibility groups: 11 subjects were non-allergic with nasal histamine hypersensitivity, 13 were non-allergic with normal sensitivity, and 12 were pollen allergic with or without nasal hypersensitivity) were exposed for three and a half hours in a climate chamber. Each subject was exposed to clean air (dust 45 +/- 38 microg/m(3) total suspended particle, TSP), house dust at 357 +/- 180 microg/m(3) TSP, house dust 382 +/- 175 microg/m(3) TSP with added glucan (50 ng/m(3)) and house dust 394 +/- 168 microg/m(3) TSP with added aldehydes corresponding to a gaseous phase of 300 microg/m(3) in the air. The study was explorative by nature. No significant effects of exposures as such were seen on break-up time, conjunctival epithelial damage score and Trolox Equivalent Antioxidant Capacity (TEAC) in tear film and subjective ratings. However, in TEAC a significant different time course was seen during exposures to aldehyde-containing dust indicating a subacute and late response to the exposures. Perceived eye irritation increased significantly during exposures to normal dust. The perception ratings were highly correlated, whereas no correlation was found between the subjective responses and the objective measurements.

PRACTICAL IMPLICATIONS

The findings indicate that measurement effects on the eyes are rather insensitive measures of short time effects of office dust exposures.

Inflammatory and allergic responses to airborne office dust in five human provocation experiments

Five studies on the effects of dust have been published from The Department of Environmental and Occupational Medicine, the University of Aarhus, Denmark. These five studies support that exposures to normal office dust for up to 5 h at concentration ranges occasionally seen in non-occupational indoor environments may cause health effects which can be measured both objectively and subjectively in healthy subjects and subjects with different types of hypersensitivity. In these five studies, the lowest observed effect level was indicated to be 75 microg/m3 (total suspended particulates). However, dust from different buildings may have different toxicity and some of the five studies had higher No Observed Effect Level (NOEL) than this value. The studies give strong evidence that dust exposures cause decreased tear film stability or break-up time and increased number of eosinophil cells in nasal lavages. There is also strong evidence that general well-being decrease during exposures. This is also reflected in increasing general irritation in eyes, nose, and throat. The combined findings support the theory that the subjects' responses to indoor dust exposures are caused by sensory perceptions, weak allergic, or weak inflammatory responses at or in the exposed tissues. More than one biological mechanism may be involved at the same time or subsequently. No signs of effects in non-exposed organs or tissues were seen, not even in sensitive persons.

PRACTICAL IMPLICATIONS

The studies indicate that dust exposures indoors may explain many reported symptoms and health effects and underlines the importance of source reduction.

Building-related symptoms and inflammatory potency of dust from office buildings

The aim was to investigate the association between building-related symptoms (BRS) in office buildings and the inflammatory potency of dust (PD). Furthermore, the association between dust potency and various building characteristics was investigated. Occupants of 22 office buildings received a retrospective questionnaire about BRS (2301 respondents). Dust was collected from groups of offices and building characteristics were recorded. The potency of a dust sample to induce interleukin-8 (IL-8) secretion from the lung epithelial cell line A549 was measured as the slope of the initial linear part of the concentration-response curve. Symptoms of the central nervous system (CNS) were associated with the potency of surface dust (OR = 1.4). This association may be due to an association between an index of CNS symptoms and dust potency in offices of 1-6 occupants (OR = 1.5). No single symptoms correlated with the potency of surface dust. The PD was not related to single building factors. The inflammatory PD may be used as an integrated proxy measure of biologically active compounds in dust, reflecting health relevant properties of the dust.

PRACTICAL IMPLICATIONS

The potency of surface dust may be used as a crude measurement of the chemical and biological exposures present in the building, and being associated with the development of central nervous system symptoms. However, additional research is needed to establish the predictive value of the potency of surface dust.

A Proposed Approach for Setting Occupational Exposure Limits for Sensory Irritants Based on Chemosensory Models

OBJECTIVES

Setting occupational exposure limits (OELs) for odorous or irritating chemicals is a global occupational health challenge. However, often there is inadequate knowledge about the toxicology of these chemicals to set an OEL and their irritation potencies are usually not recognized until they are manufactured or used in large quantities.

METHODS

In this paper, the importance of accounting for risk perception and communication; conditioned responses; and interindividual variability in tolerance, detection and susceptibility with respect to setting an OEL are discussed in relation to three chemosensory models. These parameters and models were then used to construct a flowchart-style methodology that can be used to set an OEL for a specific chemical.

RESULTS

The OEL identified for a chemical odorant or irritant will depend on the type of chemosensory effect that the chemical is likely to exhibit. For example, experience has shown that chemicals with a low odor threshold often require low OELs even though many are not toxic or do not cause irritation at those air concentrations.

CONCLUSION

In order to establish the appropriate OEL, organizations need to agree upon the percentage of the workforce that they are attempting to protect and the types of toxicological end points that are sufficiently important to protect against (e.g. transient eye irritation, enzyme induction or other reversible effects). This is particularly true for sensory irritants. The method described in this paper could also be extended to setting limits for ambient air contaminants where risk perception plays a dominant role in whether the public views the exposure as being reasonable or safe.

Persistent allergic rhinitis and indoor air quality perception--an experimental approach

In order to compare patterns of indoor air perception, including perceptions of temperature, air movement, indoor air quality (IAQ), mental concentration, and comfort, 33 subjects either with persistent allergic rhinitis or controls were exposed to different temperatures and constant relative humidity in an experimental office environment. Results were obtained by means of a self-administered visual analogue scale, analyzed using mean score comparisons and principal component analysis. At 14 degrees C, the rhinitis group reported higher scores for sensations of air dryness than controls. At 18 degrees C, in the rhinitis group, there was a correlation between dry, stagnant air, and difficult mental concentration. This group also correlated heat, dry air, and poor IAQ, in contrast to the control group, which correlated comfort, easy mental concentration, and freshness. At 22 degrees C, the rhinitis group correlated heat, dryness, stagnant air, and overall discomfort. This group also correlated non-dry air, freshness, and comfort, whereas the control group correlated heat, humidity, good indoor air, freshness, and comfort. This study suggests that the rhinitis group perceives indoor temperatures of 14 degrees C as dryer than controls do, and that at 18 and 22 degrees C this group positively correlates different adverse perceptions of IAQ. By means of a self-administered questionnaire in an experimental condition, the present study compares subjective patterns of indoor air perception from individuals with respiratory allergy (allergic rhinitis) to control individuals. It reports different patterns of perception of indoor air quality (IAQ) between the two groups, suggesting that allergic individuals could have different IAQ perception.

Interaction between ozone and airborne particulate matter in office air

This study investigated the hypotheses that humans are affected by air pollution caused by ozone and house dust, that the effect of simultaneous exposure to ozone and dust in the air is larger than the effect of these two pollutants individually, and that the effects can be measured as release of cytokines and changes of the respiratory function. Experimental exposures of eight atopic but otherwise healthy subjects were performed in a climate chamber under controlled conditions. The three controlled exposures were about 75 microg/m3 total suspended particulate matter, 0.3 p.p.m. ozone, and the combination of these. The exposure duration was 3 h. The outcome measures were interleukins and cells in nasal lavages (NAL), respiratory function, bronchial metacholine responsiveness, rhinometry symptoms and general well-being in a questionnaire and time course of general irritation on a visual analogue scale. Indications of interactions between exposure types were demonstrated for peak expiratory flow (PEF) (P<0.05) and for discomfort symptoms (P<0.03). Non-significant interactions were found for the concentration of interleukin-8 in NAL. The combined exposure was found to cause significantly more effects than either ozone exposures or dust exposures. This is interpreted as indications of a potentiation caused by the combined exposures to dust and ozone. The findings in this study are based on a limited number of subjects and thus should not be over-interpreted. However, they support the hypothesis that ozone at relatively high concentrations interacts with dust exposures to cause decrements in PEF and increase in discomfort measures.

PRACTICAL IMPLICATIONS

If confirmed at lower ozone and dust concentrations this finding could help to explain many problems with indoor air quality reported in offices throughout the world.

Quantitative determination of volatile organic compounds in indoor dust using gas chromatography-UV spectrometry

A novel technique, gas chromatography-UV spectrometry (GC-UV), was used to quantify volatile organic compounds (VOCs) in settled dust from 389 residences in Sweden. The dust samples were thermally desorbed in an inert atmosphere and evaporated compounds were concentrated by solid phase micro extraction and separated by capillary GC. Eluting compounds were then detected, identified, and quantified using a diode array UV spectrophotometer. Altogether, 28 compounds were quantified in each sample; 24 of these were found in more than 50% of the samples. The compounds found in highest concentrations were saturated aldehydes (C5-C10), furfuryl alcohol, 2,6-di-tert-butyl-4-methylphenol (BHT), 2-furaldehyde, and benzaldehyde. Alkenals were also found, notably 2-butenal (crotonaldehyde), 2-methyl-propenal (methacrolein), hexenal, heptenal, octenal, and nonenal. The concentrations of each of the 28 compounds ranged between two to three orders of magnitude, or even more. These results demonstrate the presence of a number of VOCs in indoor dust, and provide, for the first time, a quantitative determination of these compounds in a larger number of dust samples from residents. The findings also illustrate the potential use of GC-UV for analysing volatile compounds in indoor dust, some of which are potential irritants (to the skin, eyes or respiratory system) if present at higher concentrations. The potential use of GC-UV for improving survey and control of the human exposure to particle-bound irritants and other chemicals is inferred.

Ocular allergy and dry eye syndrome

PURPOSE OF REVIEW

Ocular allergy is a common clinical disorder that includes dry eye syndrome in its differential diagnosis. While ocular allergy treatments have continued to evolve since the early 1990s when the new prescription topical agents became available, there have been no major advances in the treatment of dry eye syndrome other than changes in the chemical structures of various artificial tear formulations. This review is timely and relevant due to the recent FDA approval of several new agents for the treatment of dry eye syndrome.

RECENT FINDINGS

The literature reviewed brings the practicing allergist/clinical immunologist up to date on the recent understanding that T-cell activation plays a key role in dry eye syndrome immunopathophysiology. In addition, the parallel novel treatment developments are discussed, including new formulations for tear substitutes, topical cyclosporine A and purinergic receptor (P2Y2) agonists.

SUMMARY

The recent developments bode well for patients who are referred for ocular allergy, including dry eye syndrome. A new formulation for a tear substitute that generates a 'soft gel' covering the ocular surface (in situ) is ideal for early forms of dry syndrome, while topical cyclosporine is the first new real prescription treatment for patients with moderate to severe forms of dry eye. Another potential agent to revolutionize the treatment of various disorders is based on the discovery of the purinergic receptor agonists. This is not only relevant for the production of mucin and the change in tear fluid content, but it may also have implications for other sinopulmonary disorders such as cystic fibrosis and chronic sinusitis.

Self-reported eye symptoms and related diagnostic findings--comparison of risk factor profiles

Profiles of factors affecting self-reported eye symptoms and objectively determined tear film characteristics have been examined and compared using data from 814 office workers. Multiple logistic regression analysis reveals significantly increased risks of subjective perception of eye symptoms for female gender, use of contact lenses and persons with health problems. A reduced break-up time (BUT) depends on personal criteria such as a history of eye disease and female gender. Age under 40 years, high relative humidity and formaldehyde exposure exceeding the 90th percentile are protective regarding BUT. For a thin lipid layer (as an indication of dry eyes) significantly increased risks are detected for high particle load, high endotoxin concentration and female gender. A thick lipid layer (as an indication of inflamed eyes) is significantly associated with a low educational level. The estimation of foam in the medial eye canthus seems to be unsuitable for evaluating indoor problems. The risk factor profiles agree on a few points only. The objectively examined thin lipid layer is the best eye-related indicator of the indoor environment. We therefore conclude that there is a need for the development and application of objective clinical methods for field monitoring in parallel with questioning.

PRACTICAL IMPLICATIONS

Self-reported eye symptoms in conjunction with indoor environmental problems should be validated by objective medical examinations such as semi-quantitative estimation of the superficial lipid layer, measurement of the break-up time or assessment of conjunctival epithelial damage. For unbiased proof of environmental impact, personal factors such as acute illness or low job satisfaction should be excluded. As a minimum requirement, measurements of particles, NO(2) and relative humidity (and if possible endotoxin) should be carried out to detect any indoor environmental reason for eye symptoms.

Respiratory effects of experimental exposure to office dust

The aim of this experiment was to test if healthy persons respond to exposures to normal office dust with objective or subjective effects in a dose-related way. If they did, the importance of their personal characteristics should be investigated. This paper presents the results related to respiratory effects caused by exposures to office dust. The experiment compared the responses of 24 healthy non-sensitive adult subjects with no known hyperreactivity to exposure to normal office dust in the air at 136 and 390 microg/m3 with their responses in clean air. The exposure duration was 5.25 h in a climate chamber under controlled conditions. The dust had no major identifiable specific reactive compounds. There were no direct effects of dust exposures on nasal lavages or rhinometry. The overall indications of the experiment are that healthy subjects without any hypersensitive reactions seem to respond to exposure to house dust without specific reactive components. The only effect indicated was on eosinophil cationic protein in nasal lavages and peak flow. A delayed effect on peak expiratory flow was observed the day after the exposure. Other effects were seen but in opposite direction of expectations. Several deviations from the original design of the experiment prevent any definitive conclusions from being made from these findings before they have been confirmed in future experiments to come.

PRACTICAL IMPLICATIONS

Reflecting the exploratory status of the study its major implication is to point at possible future hypotheses. The study implies that office dust may have an effect on occupants' lung function even at concentrations found in normal indoor environments. The influences of a multitude of response modifying variables were tested but no consistent pattern was found. The study does therefore not identify a specific risk group but suggests that among normal non-sensitized subjects most of the traditional risk factors can be rejected as single responsible risk factor.

Heating of indoor dust causes reduction in its ability to stimulate release of IL-8 and TNFalpha in vitro compared to non-heated dust

Dust is a major contaminant of the indoor air environment and may affect human health. Indoor dust accumulates on surfaces including heaters and light fixtures, and will be heated when these devices are used. Heat treatment of the dust may change its biologic properties and in this study we simulated the heat treatment with a dust-heating model (50-250 degrees C). The residual and the non-heated dust from seven samples were tested in cultures of fresh peripheral blood mononuclear cells and in A549 cell culture using the release of TNFalpha and IL-8, respectively, as effect indicators. The endotoxin-content and the particle size distribution of the residual and the non-heated dust suspensions were determined for some of the samples. We found that the residual dust had less ability to induce the release of TNFalpha and IL-8. The cytokine decline pattern was similar for all the dust tested and could partly be explained by the reduction in endotoxin content or possibly by inhibitory decomposition products. No correlation was found between the measured particle size distribution and the decreased cytokine levels. The results in this study suggest that the residual dust promotes reduced cytokine response and thereby a possibly lower inflammation reaction in the airways if suspended and inhaled compared with the non-heated dust.

PRACTICAL IMPLICATIONS

Accumulation of indoor dust on electric heaters and light fixtures may produce a bad odor when switched on in the cold season and some people claim respiratory distress during such events. To investigate to what extent the residuals of heated indoor dust represent a health hazard, we measured the effect in cell cultures before and after heat treatment of the dust. The in vitro results imply that the residual dust will cause a lower proinflammatory response in the airways if suspended and inhaled compared with non-heated dust. This is partly explained by heat destruction of inflammatory components in the dust.

Eye trigeminal sensitivity, tear film stability and conjunctival epithelium damage in 182 non-allergic, non-smoking Danes

The population distributions of CO(2)-induced irritation sensitivity in the eyes (COI), tear film stability (break-up time, BUT), and epithelium damage (ED) and the relation of these to basic potential confounders were assessed in an age- and gender-stratified random sample of citizens in Aarhus County, Denmark. One hundred eighty-two non-allergic, non-smoking persons participated. A general health questionnaire and an indoor air questionnaire was filled out before the measurements. The BUT was non-normally distributed, as was COI at 16% CO(2) and single ED-scores. However, COI average for all levels was normally distributed and the total score for ED was only marginally deviating. BUT decreased, the threshold to CO(2) increased, and irritation intensity at CO(2) eye exposure decreased with increasing age. ED was increased among women. There were no internal relations between the three measures, but reduced BUT was seen among subjects rating high levels of exposure to dust, electrostatic fields, and dry air. ED decreased by perceived unpleasant odors and increased with experiences of high temperatures. CO(2) sensitivity increased by perceived draught, dry air, and noise exposure prior to measurements. Selection bias cannot be excluded and the results may therefore not be truly representative of the general population. However, the results may be used as reference data for future use of measurements of break-up time, epithelium defects, and CO(2) sensitivity of the eyes in the indoor air.

PRACTICAL IMPLICATIONS

The most direct implication is that results can be used as reference level for measurements in problem buildings and for individual measurements. The reference can also be used in research and the other results as basis for future hypotheses and for support of existing hypotheses.

The effect of cleaning on dust and the health of office workers: an intervention study

BACKGROUND

Office employees often experience symptoms that could be related to indoor air exposures.

METHODS

In an office building, 114 nonsmokers who had reported mucosal irritation complaints in a survey were selected to participate in a double-blind intervention study. The intervention was carried out in Oslo, Norway, during 1998. The offices of the intervention group were given a comprehensive cleaning, whereas the offices of the control group got a superficial cleaning as a placebo treatment. Dust concentration, health complaints, and nasal congestion were recorded before and after intervention or placebo. In the intervention group, the mean dust concentration was 67 microg/m3 before intervention and 50 microg/m3 after cleaning.

RESULTS

The intervention group reported a reduction in mucosal irritation complaints (a median reduction of 1.0 irritation index points on a scale 0-8) compared with no change in the control group. The odds ratio for reporting a 2-point reduction of the mucosal irritation symptom index was 3.5 (95% confidence interval [CI] = 1.2-9.1) in the intervention group compared with the control group. Nasal congestion, measured by acoustic rhinometry, was also reduced in the intervention group. The odds ratio for reduction in nasal congestion above the 70th percentile was 4.2 (CI = 1.3-11) in the intervention group versus the control group.

CONCLUSIONS

This experimental field trial shows that comprehensive cleaning reduces the airborne dust in offices, and also can reduce mucosal symptoms and nasal congestion.

Variability of personal chemical exposure in eight office buildings in Sweden

This study focuses on the variability in chemical exposures for individuals working in office buildings. The study involved eight office buildings with 79 participants, and exposures were measured using personal samplers for volatile organic compounds, aldehydes, amines, nitrogen dioxide, ozone, and particles. Ventilation was assessed in each individual office. "Variability among buildings" and "variability among individuals" were evaluated for any component (of the 123) measured in samples from at least 20 persons, using variance component analysis and principal component analysis. Interpersonal differences explained the major part of the variance for 78% of the compounds versus between-buildings differences for 14% of the compounds. For 8% of compounds, the variation was explained in equal amounts by the differences among individuals and among buildings. This study illustrates the necessity for individualised measurements (versus stationary measurements in building) to estimate personal exposures. These results also support the conclusion that in case-referent studies of "sick building syndrome" (SBS), referents to SBS cases can be randomised for building location.

Determination of aerial microbiological contamination in scholastic sports environments

AIMS

To assess the microbiological indoor air quality (IAQ) of high school and college gyms during physical training lessons and to evaluate the effective microbiological exposure of students.

METHODS AND RESULTS

Air samples from 11 high school and college gyms of Pavia, Italy were collected. Total bacterial counts, total fungal counts and characterization of fungal taxa were determined. Air quality was evaluated using three microbiological contamination indices: the global index of microbiological contamination per m3 (GIMC per m3), the index of mesophilic bacterial contamination (IMC) and the amplification index (AI).

CONCLUSIONS

This work testifies that air contamination in indoor gyms is always superior to that of the outdoor environment. Nevertheless, students are exposed to relatively low concentrations of airborne micro-organisms. The highest values of fungal counts and GIMC per m3 (>14,661) were observed between April and October when the central heating systems were switched off. The lowest fungal counts were detected in modern buildings equipped with forced ventilation systems. From qualitative aeromycological studies, 45 fungal taxa were identified, and different potentially allergenic species were isolated.

SIGNIFICANCE AND IMPACT OF THE STUDY

The standardization of air sampling methods and the correct evaluation of aeromicrobiological results allow the classification of indoor air healthiness. The proposed microbiological contamination indices together with the characterization of airborne fungal taxa are useful tools for detailed description of IAQ.

A chamber-experiment investigation of the interaction between perceptions of noise and odor in humans

OBJECTIVES

This study was designed to investigate human comfort and health effects following exposure to noise and odor and to explore the interaction between perceptions of noise and odor in humans.

MATERIALS AND METHODS

Nine healthy subjects were randomly exposed to noise, odor, and their combination, in a 3 x 3 Latin square design for 80 min in an exposure chamber. Continuous noise was broadcast at an average level of 75 dBA by a loudspeaker, and odor was provided by furfurylmercaptan (a coffee-aroma constituent). A standardized 28-item questionnaire, together with mood-scale ratings, nasal dimensions by acoustic rhinometry, addition tests for distraction, and skin humidity, were performed before and at the end of exposure.

RESULTS

In the questionnaire investigation, the perceived "sound level" was significantly affected by noise and the combined exposures, while "odor intensity", "air quality", and "need more ventilation" was significantly affected by odor and the combined exposures. Perceptions of symptoms became worse with increasing exposure time, such as perceived "dry nose" and "sleepiness" by odor and combined exposures, "headache" by noise, "concentration difficulty", "general well being", and "stressed by being in the chamber" by noise, odor and combined exposures. In addition, the occurrence of interactions was analyzed by comparison of the ratings of perceived "sound level", "odor intensity", "air quality", and "need more ventilation" during the combined exposure with two single exposures. Insignificant interaction was found but it indicated a decreased tendency to perceptions of discomfort from "odor intensity", "air quality", and "need for more ventilation" when noise was added to odor exposure.

CONCLUSION

It may be concluded that noise and odor cause discomfort in humans. Moreover, the study might indicate that additions of noise reduce (mask) the perception of discomfort from odor, and additions of odor have no or little affect on the perception of noise.

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.

Effects of low-toxicity particulate matter on human nasal function

Chronic nasal and paranasal sinus problems affect approximately 15% of the population in industrialized countries. Recent studies suggest that particulate matter might contribute to this condition. The effects of acute exposure to low-toxicity particulate matter on human nasal airflow, mucociliary transport, and nasal discomfort should be assessed. Thirty-two healthy volunteers were exposed to 0 (control), 500, 1000, and 5000 micrograms/m3 calcium carbonate dust for 3 hours and nasal saccharin transport time (STT), rhinomanometry, and visual analog scales (VAS) on nasal discomfort were obtained. A dose dependent decrease of STT (P = 0.02) and nasal patency (P = 0.04), and increased sensation of nasal obstruction (P = 0.002) and dryness (P = 0.03) was observed. The results indicate that acute exposure to low-toxicity particulate matter in concentrations frequently encountered in western agglomeration areas may affect nasal functions and cause nasal symptoms.

Effects in the eyes caused by exposure to office dust

This Danish Office Dust Experiment compares the responses of 24 normal non-sensitive adult subjects to exposure to normal office dust in the air at 136 and 390 micrograms/m3 (median) and to their responses in clean air. The exposure duration was 5 1/4 h in a climate chamber under controlled conditions. The dust had no major identifiable specific reactive compounds. The overall conclusion is that healthy subjects without any hypersensitive reactions seem to respond to exposure to the house dust. The effects observed were all found in interaction with response modifying factors. The effects were a decrease in inflammatory cells in tear fluids, increased epithelium defects, and a decrease in break-up time. No effect was seen on eye reddening, or eye sensitivity to CO2. As no specific hypotheses could be specified before the study for the observed interactions, no definitive conclusions can be made. Furthermore, it seemed that there was no consistency in the interacting factors after the exposure and the next morning. A tentative analysis of the effects of the importance of personal characteristics showed that only a minority within the subject group may respond to the exposure. However, no common set of sensitivity measures could be defined for these responders.

Indoor particles and symptoms among office workers: results from a double-blind cross-over study

BACKGROUND

We studied the effects of removing small airborne particles in an office building without unusual contaminant sources or occupant complaints.

METHODS

We conducted a double-blind crossover study of enhanced particle filtration in an office building in the Midwest United States in 1993. We replaced standard particle filters, in separate ventilation systems on two floors, with highly efficient filters on alternate floors weekly over 4 weeks. Repeated-measures models were used to analyze data from weekly worker questionnaires and multiple environmental measurements.

RESULTS

Bioaerosol concentrations were low. Enhanced filtration reduced concentrations of the smallest airborne particles by 94%. This reduction was not associated with reduced symptoms among the 396 respondents, but three performance-related mental states improved; for example, the confusion scale decreased (-3.7%; 95% confidence limits (CL) = -6.5, -0.9). Most environmental dissatisfaction variables also improved; eg, "stuffy" air, -5.3% (95% CL = -10.3, -0.4). Cooler temperatures within the recommended comfort range were associated with remarkably large improvement in most outcomes; for example, chest tightness decreased -23.4% (95% CL = -38.1, -8.7) for every 1 degrees C decrease.

CONCLUSIONS

Benefits of enhanced filtration require assessment in buildings with higher particulate contaminant levels in studies controlling for temperature effects. Benefits from lower indoor temperatures need confirmation.