COVID 19 - Possible interrelations with respiratory comorbidities caused by occupational exposure to various hazardous bioaerosols. Part II. Clinical course, diagnostics, treatment and prevention.

INTRODUCTION AND OBJECTIVE: The course of COVID-19 caused by the SARS-CoV-2 may be aggravated by bioaerosols containing other viruses, bacteria, and fungi, occurring mainly in the occupational environment. Hence, the diagnostics and treatment of COVID-19 should address such a possibility in the anamnesis, treatment and final recommendations for avoiding of adverse exposure. ABBREVIATED DESCRIPTION OF THE STATE OF KNOWLEDGE: As SARS-CoV-2 attacks primarily the respiratory system and the severe manifestation of COVID-19 is interstitial pneumonia, diagnostics should include the following clinical and laboratory examinations: chest X-ray; high resolution computed tomography (HRCT); pulmonary function tests; arterial-blood gas test; genetic tests for the presence of SARS-CoV-2, in the future with the use of highly specific and sensitive nano-based biosensors; tests for the presence of specific immunity against the antigens of microorganisms causing other infectious or allergic pulmonary diseases (in the case of anamnestic indications). Because an universally accepted treatment for COVID-19 does not exist, the hitherto prescribed antiviral and immune-modulating drugs should be used be with caution. In many cases, a better alternative could be a safe supportive therapy, such as supplementation of the diet with probiotics, prebiotics, vitamins and microelements. SUMMARY: The most important preventive measures against COVID-19 should include: vaccination; the use of filter or surgical masks; disinfection and sterilization; maintaining of well-functioning ventilation and air conditioning systems; reduction of the community air pollution which has been identified as an important factor increasing the COVID-19 severity. In the choice of preventive measures, the above should be considered for their potential efficacy against other bioaerosols as potential disease-aggravating agents.

Biological effects of inhaled hydraulic fracturing sand dust VII. Neuroinflammation and altered synaptic protein expression.

Hydraulic fracturing (fracking) is a process used to recover oil and gas from shale rock formation during unconventional drilling. Pressurized liquids containing water and sand (proppant) are used to fracture the oil- and natural gas-laden rock. The transportation and handling of proppant at well sites generate dust aerosols; thus, there is concern of worker exposure to such fracking sand dusts (FSD) by inhalation. FSD are generally composed of respirable crystalline silica and other minerals native to the geological source of the proppant material. Field investigations by NIOSH suggest that the levels of respirable crystalline silica at well sites can exceed the permissible exposure limits. Thus, from an occupational safety perspective, it is important to evaluate the potential toxicological effects of FSD, including any neurological risks. Here, we report that acute inhalation exposure of rats to one FSD, i.e., FSD 8, elicited neuroinflammation, altered the expression of blood brain barrier-related markers, and caused glial changes in the olfactory bulb, hippocampus and cerebellum. An intriguing observation was the persistent reduction of synaptophysin 1 and synaptotagmin 1 proteins in the cerebellum, indicative of synaptic disruption and/or injury. While our initial hazard identification studies suggest a likely neural risk, more research is necessary to determine if such molecular aberrations will progressively culminate in neuropathology/neurodegeneration leading to behavioral and/or functional deficits.

Pressurized Intraperitoneal Aerosol Chemotherapy, a Palliative Treatment Approach for Patients With Peritoneal Carcinomatosis: Description of Method and Systematic Review of Literature.

BACKGROUND: Peritoneal metastases arise in patients with a variety of primary cancers, and are associated with a poor prognosis. Systemic chemotherapy is the mainstay of treatment; however, the morbidity is considerable and the survival benefit is modest. Cytoreductive surgery and heated intraperitoneal chemotherapy is a potentially curative treatment available to a minority of patients; however, most develop recurrent disease. A novel palliative treatment for peritoneal metastases, pressurized intraperitoneal aerosol chemotherapy, has recently been introduced. Pressurized intraperitoneal aerosol chemotherapy utilizes an aerosol of chemotherapy in carbon dioxide gas. It is instilled into the abdomen under pressure via laparoscopic ports. No cytoreduction is performed. Pressurized intraperitoneal aerosol chemotherapy can be repeated at 6-week intervals. Oxaliplatin or cis-platinum and doxorubicin have been used to date. OBJECTIVE: This study aims to systematically review and evaluate the method, and the preclinical and early clinical results of pressurized intraperitoneal aerosol chemotherapy. DATA SOURCES: Medline and the Cochrane Library were the data sources for the study. STUDY SELECTION: Peer-reviewed series of greater than 10 patients, with sufficient patient data, through April 2019, were selected. INTERVENTION: Patients with peritoneal metastases underwent pressurized intraperitoneal aerosol chemotherapy. MAIN OUTCOME MEASURES: Patient dropout, histologic tumor response, adverse events, and 30-day mortality were the primary outcomes measured. RESULTS: A total of 921 patients with peritoneal metastases were brought to the operating room for pressurized intraperitoneal aerosol chemotherapy. The number of pressurized intraperitoneal aerosol chemotherapy treatments administered was as follows: 1 treatment, 862 (94%); 2 treatments, 645 (70%); and 3 treatments, 390 patients (42%). Initial laparoscopic access was not possible in 59 patients (6.4%). Common Terminology Criteria for Adverse Events grade 3 or higher were noted in 13.7% of the patients who, collectively, underwent a total of 2116 treatments. The 30-day mortality was 2.4% (22/921). LIMITATIONS: This study was limited by the heterogeneity of reported data and primary tumor types and by the lack of long-term survival data. CONCLUSIONS: Early clinical results are encouraging, but tumor-specific, prospective, randomized trials are needed to compare pressurized intraperitoneal aerosol chemotherapy to systemic chemotherapy. This method has yet to be introduced to the United States. It is another therapeutic option for patients with peritoneal metastases and will broaden the patient base for future clinical trials.

Unusual winter Saharan dust intrusions at Northwest Spain: Air quality, radiative and health impacts.

Saharan air masses can transport high amounts of mineral dust particles and biological material to the Iberian Peninsula. During winter, this kind of events is not very frequent and usually does not reach the northwest of the Peninsula. However, between 21 and 22 February 2016 and between 22 and 23 February 2017, two exceptional events were registered in León (Spain), which severely affected air quality. An integrative approach including: i) typical synoptic conditions; ii) aerosol chemical composition; iii) particle size distributions; iv) pollen concentration; v) aerosol optical depth (AOD); vi) radiative forcing and vii) estimation of the impact of aerosols in the respiratory tract, was carried out. In the global characterization of these events, the exceedance of the PM10 daily limit value, an increase in the coarse mode and a rise in the iron concentration were observed. On the 2016 event, an AOD and extinction-related Ångström exponent clearly characteristic of desert aerosol (1.1 and 0.05, respectively) were registered. Furthermore, pollen grains not typical of flowering plants in this period were identified. The chemical analysis of the aerosol from the 2017 event allowed us to confirm the presence of the main elements associated with mineral sources (aluminum, calcium, and silica concentrations). An increase in the SO42-, NO3- and Cl- concentrations during the Saharan dust intrusion was also noted. However, in this event, there was no presence of atypical pollen types. The estimated dust radiative forcing traduced a cooling effect for surface and atmosphere during both events, corroborated by trends of radiative flux measurements. The estimated impact on the respiratory tract regions of the high levels of particulate matter during both Saharan dust intrusions showed high levels for the respirable fraction.

Effect of Kuanxiong Aerosol () on Patients with Angina Pectoris: A Non-inferiority Multi-center Randomized Controlled Trial.

OBJECTIVE: To evaluate the effect and safety of Kuanxiong Aerosol (, KA) on patients with angina pectoris. METHODS: Block randomization was performed to randomly allocate 750 patients into KA (376 cases) and control groups (374 cases). During an angina attack, the KA group received 3 consecutive sublingual sprays of KA (0.6 mL per spray). The control group received 1 sublingual nitroglycerin tablet (NT, 0.5 mg/tablet). Log-rank tests and Kaplan-Meier estimations were used to estimate the angina remission rates at 6 time-points after treatment (1, 2, 3, 4, 5, and >5 min). Logistic regression analysis was performed to observe the factors inflfluencing the rate of effective angina remission, and the remission rates and incidences of adverse reactions were compared for different Canadian Cardiovascular Society (CCS) classes of angina. RESULTS: The 5-min remission rates in the KA and control groups were not signifificantly different (94.41% vs. 90.64%, P>0.05). The angina CCS class signifificantly inflfluenced the rate of remission (95% confidence interval = 0.483-0.740, P<0.01). In the CCS subgroup analysis, the 3-and 5-min remission rates for KA and NT were similar in the CCSII and III subgroups (P>0.05), while they were signifificantly better for KA in the CCSI and II subgroups (P<0.05 or P<0.01). Furthermore, the incidence of adverse reactions was signifificantly lower in the KA group than in the control group for the CCSII and III subgroups (9.29% vs. 26.22%, 10.13% vs. 20.88%, P<0.05 or P<0.01). CONCLUSIONS: KA is not inferior to NT in the remission of angina. Furthermore, in CCSII and III patients, KA is superior to NT, with a lower incidence of adverse reactions. (Registration No. ChiCTRIPR-15007204).

Lidocaine Spray Versus Paracervical Block During Loop Electrosurgical Excision Procedure: A Randomized Trial.

OBJECTIVE: The aim of the study was to compare the effectiveness of pain control between lidocaine spray (LS) and paracervical block (PB) with lidocaine during the loop electrosurgical excision procedure (LEEP). MATERIALS AND METHODS: A single-blinded randomized controlled trial was conducted on 132 women who underwent LEEP of the cervix. The participants were randomly allocated to either a PB group or a LS group. The PB group participants were anesthetized by PB using 10 mL of 2% lidocaine with 1:100,000 of epinephrine. The LS group participants were locally anesthetized with four puffs (40 mg) of 10% LS, which was applied thoroughly to the cervix. Pain scores, using 10-cm visual analog scales, were obtained and compared for participants in both groups during anesthesia, during excision and 30 minutes after excision. RESULTS: A total of 132 LEEPs were performed with 66 in LS group and 66 in PB group. The mean (SD) pain scores during excision were 5.2 (2.4) in the LS group and 4.2 (3.3) in the PB group (mean difference = 1.1, 95% CI = 0.8 to 2.1, p = .033), which was within the nonclinically significant margin of this study. The baseline pain score after speculum examination was not significantly different in both groups. There was no adverse effect in the LS group compared with eight cases in the PB group (tinnitus, numbness, palpitation or tachycardia, and hypertension). CONCLUSIONS: The local 40 mg of 10% LS can be used to substitute for PB for pain control during LEEP of the cervix. It also resulted in fewer adverse effects.

Health Impact Assessment of Asian Dust/Cross-border Air Pollutant and Necessary Preventive Measure.

The health effects of Asian dust (mineral dust) originating from dry lands such as the Gobi Desert and Taklamakan Desert have recently been a concern. In addition to Asian dust, transboundary airborne microparticles that reach Japan include various types of aerosol, such as artificial air pollutants and smoke from combustion. They originate from densely populated areas and are transported along the same route as Asian dust. We analyzed environmental factors and subjective symptoms involving the respiratory organ, nose, eyes, and skin using a conventional equation for estimation, and found that symptoms with a significant risk of worsening varied according to the type of pollutants reaching Japan. We also analyzed the synergistic effects of Asian dust and pollens on nasal symptoms using a two-pollutant model. The odds ratio for symptoms at the time of arrival of a high concentration of Asian dust was 1.37 (95% confidence interval: 1.19-1.58), but the odds ratio adjusted for pollens was 1.18 (95% confidence interval: 1.04-1.34). Although the influence on nasal symptoms overlapped somewhat between Asian dust and pollens, that of Asian dust remained significant. Regarding preventive measures against symptoms, we examined the rate of particle leakage into masks. We found that it is important to wear a mask that fits an individual's facial features and has no gap between the face and the mask. In addition, we report our attempt to construct models for predicting aerosol arrival and forecasting health to establish preventive measures against aerosols.

[About an unusual case of lipoid pneumonia]. / À propos d'un cas original de pneumonie lipidique.

Lipoid pneumonia, although uncommon, should be considered when patients had a chronic pneumonia. We report a case of a 40-year-old female who presented with a chronic pneumonia. The CT-scan analysis, then the bronchoalveolar lavage, revealed a lipoid pneumonia. This lipoid pneumonia was caused by chronic inhalation of niaoulis vapors. This etiology has not been described in the literature. Alveolar condensation disappeared one month after bronchoalveolar lavage. This suggests that bronchoalveolar lavage may contribute to opacity regression besides exogenous lipid eviction.

Exposures and cross-shift lung function declines in wildland firefighters.

Respiratory problems are common among wildland firefighters. However, there are few studies directly linking occupational exposures to respiratory effects in this population. Our objective was to characterize wildland fire fighting occupational exposures and assess their associations with cross-shift changes in lung function. We studied 17 members of the Alpine Interagency Hotshot Crew with environmental sampling and pulmonary function testing during a large wildfire. We characterized particles by examining size distribution and mass concentration, and conducting elemental and morphological analyses. We examined associations between cross-shift lung function change and various analytes, including levoglucosan, an indicator of wood smoke from burning biomass. The levoglucosan component of the wildfire aerosol showed a predominantly bimodal size distribution: a coarse particle mode with a mass median aerodynamic diameter about 12 µm and a fine particle mode with a mass median aerodynamic diameter < 0.5 µm. Levoglucosan was found mainly in the respirable fraction and its concentration was higher for fire line construction operations than for mop-up operations. Larger cross-shift declines in forced expiratory volume in one second were associated with exposure to higher concentrations of respirable levoglucosan (p < 0.05). Paired analyses of real-time personal air sampling measurements indicated that higher carbon monoxide (CO) concentrations were correlated with higher particulate concentrations when examined by mean values, but not by individual data points. However, low CO concentrations did not provide reliable assurance of concomitantly low particulate concentrations. We conclude that inhalation of fine smoke particles is associated with acute lung function decline in some wildland firefighters. Based on short-term findings, it appears important to address possible long-term respiratory health issues for wildland firefighters. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resources: a file containing additional information on historical studies of wildland fire exposures, a file containing the daily-exposure-severity questionnaire completed by wildland firefighter participants at the end of each day, and a file containing additional details of the investigation of correlations between carbon monoxide concentrations and other measured exposure factors in the current study.].

Aerosols from biomass burning and respiratory diseases in children, Manaus, Northern Brazil.

OBJECTIVE: To investigate the effects of fine particulate matter emitted through biomass burning on hospitalizations for respiratory diseases in children living in Manaus, Northern Brazil. METHODS: Descriptive study with ecologic time series design carried out in Manaus from 2002 to 2009. Hospital admission data were obtained from the Unified Health System database. PM2.5 levels were estimated using aerosol remote sensing through the measurement of aerosol optical depth at a wavelength of 550 nm. Statistical methods were used in the data analysis, with Pearson correlation and multiple linear regression between variables, with a 95% confidence interval. RESULTS: The region of Manaus showed low PM2.5 concentrations when compared to the Southern Amazonian region. Between August and November (dry period in the region), was when the highest mean levels of PM2.5, estimated between 18 to 23 µg/m3, and the largest number of fires were observed. For the rainy season, an average of 12 µg/m3, 66% lower than the dry season measurements (20.6 µg/m3) was observed. The highest rates of hospitalization were observed during the rainy season and April was the month with the highest levels at 2.51/1,000 children. A positive association between hospital admissions and relative humidity (R = 0.126; p-value = 0.005) was observed, while the association between admissions and PM2.5 was negative and statistically significant (R = -0.168; p-value = 0.003). The R 2 of the final model (Hospitalizations = 2.19*Humidity - 1.60*PM2.5 - 0.23*Precipitation) explained 84% of hospitalizations due to respiratory disease in children living in Manaus, considering the independent variables statistically significant (humidity, PM2.5, and precipitation). CONCLUSIONS: Hospital admissions for respiratory diseases in children in Manaus, were more related to weather conditions and in particular relative humidity, than to exposure to aerosols emitted by biomass burning in the Amazonian region.

Aerossois de queimadas e doencas respiratorias em criancas, Manaus, Brasil / Aerosols from biomass burning and respiratory diseases in children, Manaus, Northern Brazil

OBJETIVO: Analisar a relação entre a exposição ao material particulado fino emitido em queimadas e as internações hospitalares por doenças respiratórias em crianças. MÉTODOS: Estudo descritivo com delineamento ecológico de séries temporais realizado em Manaus de 2002 a 2009. Os dados de internações hospitalares foram obtidos a partir do banco de dados do Sistema Único de Saúde. Os níveis de PM2.5 foram estimados por sensoriamento remoto a partir da espessura ótica de aerossóis no comprimento de onda de 550 nm. Foram utilizadas a correlação de Pearson e a regressão linear múltipla entre as variáveis com intervalo de 95% de confiança. RESULTADOS: A região de Manaus apresentou baixas concentrações de PM2.5, quando comparada com a porção sul da região Amazônica. Os meses de agosto a novembro (período seco) apresentaram os maiores níveis médios de PM2.5 (de 18 a 23 µg/m³) e os maiores números de focos de queimadas detectados. A média do PM2.5 para a estação chuvosa foi de 12 µg/m³, 66% menor que a média da estação seca, 20,6 µg/m³. As maiores taxas de internações ocorreram durante a estação chuvosa, e o mês de abril teve a maior taxa, com 2,51/1.000 crianças. Foi observada associação positiva significativa entre as internações e a umidade relativa (R = 0,126; p = 0,005), enquanto a associação entre internações com PM2.5 mostrou-se negativa e estatisticamente significativa (R = - 0,168; p = 0,003). O R² do modelo final (Internações = 2,19*Umidade - 1,60*PM2.5 - 0,23*Precipitação) explicou em 84% as internações por doenças respiratórias em ...

OBJECTIVE To investigate the effects of fine particulate matter emitted through biomass burning on hospitalizations for respiratory diseases in children living in Manaus, Northern Brazil. METHODS Descriptive study with ecologic time series design carried out in Manaus from 2002 to 2009. Hospital admission data were obtained from the Unified Health System database. PM2.5 levels were estimated using aerosol remote sensing through the measurement of aerosol optical depth at a wavelength of 550 nm. Statistical methods were used in the data analysis, with Pearson correlation and multiple linear regression between variables, with a 95% confidence interval. RESULTS The region of Manaus showed low PM2.5 concentrations when compared to the Southern Amazonian region. Between August and November (dry period in the region), was when the highest mean levels of PM2.5, estimated between 18 to 23 µg/m3, and the largest number of fires were observed. For the rainy season, an average of 12 µg/m3, 66% lower than the dry season measurements (20.6 µg/m3) was observed. The highest rates of hospitalization were observed during the rainy season and April was the month with the highest levels at 2.51/1,000 children. A positive association between hospital admissions and relative humidity (R = 0.126; p-value = 0.005) was observed, while the association between admissions and PM2.5 was negative and statistically significant (R = -0.168; p-value = 0.003). The R 2 of the final model (Hospitalizations = 2.19*Humidity - 1.60*PM2.5 - 0.23*Precipitation) explained 84% of hospitalizations due to respiratory disease in children living in Manaus, considering the independent variables statistically significant (humidity, PM2.5, and precipitation). CONCLUSIONS Hospital admissions for respiratory diseases in children in Manaus, were more related to weather conditions and in ...

Impact of in-barn manure separation on biological air quality in an experimental setup identical to that in swine buildings.

In-barn manure separation systems are becoming popular due to various environmental pressures on the swine industry. According to the literature, separation of feces and urine directly underneath the slats should have a positive impact on barn air quality. Removal and rapid separation of the two phases (solid/liquid) would reduce the dust and bioaerosol emissions, which would significantly improve the air quality in pig-housing facilities. From an occupational health and safety perspective, the maximum endotoxin and total bacteria concentrations to ensure workers' safety should not exceed 450 endotoxin units per cubic meter of air (EU m(-3)) and 10(4) colony-forming units per cubic meter of air (CFU m(-3)), respectively. In the current study, the effect on air quality of six in-barn manure handling systems was measured. A flat scraper system and four separation systems installed under the slats (a conveyor belt system, a conveyor net system, and a V-shaped scraper operated at two operation frequencies) were evaluated and compared to a conventional pull-plug system (control). The experiment took place in twelve independent and identical rooms housing four grower-finisher pigs each, and air samples were collected and analyzed for total dust, endotoxins, bacteria, and mold counts. The results obtained from this experimental setup show that the separation of feces and urine under the slats would concentrate at least 80% of the phosphorus in the solid phase. The total bacteria and endotoxin concentrations are lower than those found in commercial hog barns but remain higher than the recommended levels. Only the total dust concentrations are approximately 10% of their regulated value. This separation has no impact on dust and bioaerosol concentrations compared to the control.

Spray droplet size, drift potential, and risks to nontarget organisms from aerially applied glyphosate for coca control in Colombia.

A wind tunnel atomization study was conducted to measure the emission droplet size spectra for water and Glyphos (a glyphosate formulation sold in Colombia) + Cosmo-flux sprays for aerial application to control coca and poppy crops in Colombia. The droplet size spectra were measured in a wind tunnel for an Accu-Flo nozzle (with 16 size 0.085 [2.16 mm] orifices), under appropriate simulated aircraft speeds (up to 333 km/h), using a laser diffraction instrument covering a dynamic size range for droplets of 0.5 to 3,500 microm. The spray drift potential of the glyphosate was modeled using the AGDISP spray application and drift model, using input parameters representative of those occurring in Colombia for typical aerial application operations. The droplet size spectra for tank mixes containing glyphosate and Cosmo-Flux were considerably finer than water and became finer with higher aircraft speeds. The tank mix with 44% glyphosate had a D(v0.5) of 128 microm, while the value at the 4.9% glyphosate rate was 140 microm. These are classified as very fine to fine sprays. Despite being relatively fine, modeling showed that the droplets would not evaporate as rapidly as most similarly sized agricultural sprays because the nonvolatile proportion of the tank mix (active and inert adjuvant ingredients) was large. Thus, longer range drift is small and most drift that does occur will deposit relatively close to the application area. Drift will only occur downwind and, with winds of velocity less than the modeled maximum of 9 km/h, the drift distance would be substantially reduced. Spray drift potential might be additionally reduced through various practices such as the selection of nozzles, tank mix adjuvants, aircraft speeds, and spray pressures that would produce coarser sprays. Species sensitivity distributions to glyphosate were constructed for plants and amphibians. Based on modeled drift and 5th centile concentrations, appropriate no-spray buffer zones (distance from the end of the spray boom as recorded electronically +/-5%) for protection of sensitive plants were 50-120 m for coca spray scenarios and considerably lower for poppy spray scenarios. The equivalent buffer zone for amphibia was 5 m. The low toxicity of glyphosate to humans suggests that these aerial applications are not a concern for human health.

Toxic carriers in pepper sprays may cause corneal erosion.

We describe four patients who developed corneal erosion after an exposure to a pepper spray containing toxic carriers. Two of these patients were exposed to a pepper gas containing 5% oleoresin capsicum (OC) as an irritant and 92% trichlorethylene or unknown amount of dichloromethane as a carrier. One patient was exposed to a mock (containing 92% trichlorethylene as a carrier) training pepper gas without OC. The fourth patient was exposed to an unidentified Russian pepper gas spray. Two of the patients were examined by in vivo confocal microscopy to demonstrate the depth and quality of the stromal damage. To test the toxicity of the commercial tear spray, it was analyzed and test sprayed on a soft contact lens and into a plastic cup. Visual acuity was measured and the eyes were examined with a slit-lamp up to 5 months. Physical damage to a soft contact lens was visually acquired. All patients showed a long-lasting, deep corneal and conjuctival erosion, which resolved partly with medical therapy during the following weeks/months. Confocal microscopy revealed corneal nerve damage, and keratocyte activation reaching two-thirds of stroma for one patient. The spray caused serious damage to both the soft contact lens and the plastic cup. The safety of the commercially available pepper sprays should be assessed before marketing, and a list of acceptable ingredients created. The sprays should also have instructions on the use of the compound as well as on the first aid measures after the exposure. Solvents known to be toxic should not be used.

Petrol sniffing in Aboriginal communities: a review of interventions.

Petrol sniffing (and other forms of inhalant misuse) occur within some Aboriginal communities across Australia. However, there is little documented information about the nature and combination of interventions that are most effective in addressing it. This article reviews published and unpublished literature relevant to petrol sniffing in Australian Aboriginal communities. A range of strategies which have been trialled previously are discussed under the categories of primary, secondary and tertiary intervention. We have adopted Zinberg's schema of 'drug', 'set' and 'setting' in theorizing the mix of interventions most likely to reduce petrol sniffing. We argue that interventions should address as many as possible of these factors. Further, while no strategy is likely to succeed without strong support from local community members, governments also have an important role in addressing petrol sniffing. Consistent funding for strategies directly addressing petrol sniffing and co-ordinated government responses to the broader needs of Aboriginal young people and their communities are critical.

A simple method to protect patient and environment when using sandblasting for intraoral repair.

Repair or correction of intraoral restorations can be an alternative to complete replacement. A simple sandblasting device is very effective in producing a microretentive surface on every restorative material. A disadvantage of the technique is the production of an aerosol contaminated with the small, abrasive aluminum-oxide particles. In this article, a simple solution is given to protect the patient and environment against this dust during intraoral reparatory procedures involving sandblasting.

Determinants of the bronchial response to high molecular weight occupational agents in a dry aerosol form.

In occupational challenge tests with isocyanate vapours, bronchial responsiveness is determined by the total dose rather than the concentration or duration of exposure. Whether the same applies for high molecular weight (HMW) agents in powder form is unknown. The aim of this study was to determine whether the total dose of HMW agents in powder form is responsible for the immediate reaction documented in specific challenge tests. Included in the study were nine subjects (seven males and two females) with a diagnosis of occupational asthma proved by specific challenge tests carried out on a preliminary visit. Two challenge tests (using a closed-circuit exposure chamber) were performed at an interval of 2 weeks; the concentrations administered in a random order on these two visits were half and double the one that had caused a 20% fall in forced expiratory volume in one second (FEV1) on a preliminary visit. The duration of exposure was adjusted until a significant fall in FEV1 (target of 20%) occurred. The two concentrations obtained were significantly different, by 2.07+/-0.36-fold (SD). The observed durations of exposure leading to a 20% fall in FEV1 on the two visits also differed significantly by 0.46+/-0.32-fold. Consequently, the cumulative efficient doses were not significantly different between the two visits: 12+/-5.4 and 9+/-5 mg x mL(-1) x min(-1), respectively. The corresponding cumulative dose ratio was 0.96+/-0.61. The expected duration of exposure (10.8+/-24 min) was not significantly different from the observed duration (5.4+/-9 min). The mean and 95% confidence interval for the difference in concentration between the two visits was 1.83-fold (1.48-2.21). In conclusion, the total dose rather than the concentration or duration of exposure per se determines bronchial responsiveness to high molecular weight agents in powder form.

The effects of particle charge on the performance of a filtering facepiece.

This study quantitatively determined the effect of electrostatic charge on the performance of an electret filtering facepiece. Monodisperse challenge corn oil aerosols with uniform charges were generated using a modified vibrating orifice monodisperse aerosol generator. The aerosol size distributions and concentrations upstream and downstream of an electret filter were measured using an aerodynamic particle sizer, an Aerosizer, and a scanning mobility particle sizer. The aerosol charge was measured by using an aerosol electrometer. The tested electret filter had a packing density of about 0.08, fiber size of 3 microns, and thickness of 0.75 mm. As expected, the primary filtration mechanisms for the micrometer-sized particles are interception and impaction, especially at high face velocities, while electrostatic attraction and diffusion are the filtration mechanisms for submicrometer-sized aerosol particles. The fiber charge density was estimated to be 1.35 x 10(-5) coulomb per square meter. After treatment with isopropanol, most of fiber charges were removed, causing the 0.3-micron aerosol penetration to increase from 36 to 68%. The air resistance of the filter increased slightly after immersion in the isopropanol, probably due to the coating of impurities in isopropanol. The aerosol penetration decreased with increasing aerosol charge. The most penetrating aerosol size became larger as the aerosol charge increased, e.g., from 0.32 to 1.3 microns when the aerosol charge increased from 0 to 500 elementary charges.

A review of exposure conditions and possible health effects associated with aerosol and vapour from low-aromatic oil-based drilling fluids.

This paper reviews investigations on possible health effects after inhalation of aerosol and vapour from the low-aromatic oil-based drilling fluids which have replaced the diesel-based fluids. The main advantage of the low-aromatic base oils with respect to health hazard is their lower volatility. However, some aliphatic and naphthenic hydrocarbons are distributed more efficiently to the brain than are the corresponding aromatic ones. Reducing the content of aromatic hydrocarbons becomes particularly important when the upper end of the boiling point range is sufficiently high for the base oil to contain carcinogenic polycyclic aromatic hydrocarbons (PAH). As a result of enclosure and local extract ventilation it has been possible to reduce time-weighted average concentrations of aerosol and vapour to below 100 mg m-3. Effects on the central nervous system have only been observed at higher concentrations of the actual hydrocarbons, and male rat hydrocarbon nephropathy is not considered predictive of a normal human response. Insufficient information is available on possible long-term effects of exposure to the low-aromatic oil-based drilling fluids, especially regarding carcinogenicity and changes in the lungs.