Impact of improved indoor air quality in Nunavik homes on children's respiratory health.

Between 2007 and 2012, hospitalization rate related to respiratory system diseases in children ≤1-year-old was near 7 times higher in Nunavik compared with the whole province of Quebec. To assess the impact of poor indoor air quality (IAQ) in residential environments on children's respiratory health, the Nunavik's intervention study investigated the impact of the optimization of ventilation systems on the incidence rates of respiratory infections in children in Nunavik. Children under 10 years were recruited and categorized according to the type of ventilation system in their home: energy recovery ventilator (ERV), heat recovery ventilator (HRV), no HRV or ERV, and control groups. Children's' medical records were analyzed over a period of 50 weeks pre- and post-intervention. Clinical diagnoses were classified into 4 categories: upper respiratory infections, lower respiratory infections, otitis media, and asthma. A decrease in respiratory infections episodes was observed in all groups following intervention with the highest impact observed for HRV systems (-53.0%). Decreases in the ERV group were not significant (-21,7%) possibly due to the presence of some volatile organic compound (such as propylene glycol) and inerrant experimental bias. Nevertheless, no significant association was found between health episodes incidence and household's behaviors or IAQ.

Indoor air quality assessment in dwellings with different ventilation strategies in Nunavik and impacts on bacterial and fungal microbiota.

Indoor air quality is a major issue for public health, particularly in northern communities. In this extreme environment, adequate ventilation is crucial to provide a healthier indoor environment, especially in airtight dwellings. The main objective of the study is to assess the impact of ventilation systems and their optimization on microbial communities in bioaerosols and dust in 54 dwellings in Nunavik. Dwellings with three ventilation strategies (without mechanical ventilators, with heat recovery ventilators, and with energy recovery ventilators) were investigated before and after optimization of the ventilation systems. Indoor environmental conditions (temperature, relative humidity) and microbiological parameters (total bacteria, Aspergillus/Penicillium, endotoxin, and microbial biodiversity) were measured. Dust samples were collected in closed face cassettes with a polycarbonate filter using a micro-vacuum while a volume of 20 m3 of bioaerosols were collected on filters using a SASS3100 (airflow of 300 L/min). In bioaerosols, the median number of copies was 4.01 × 103 copies/m3 of air for total bacteria and 1.45 × 101 copies/m3 for Aspergillus/Penicillium. Median concentrations were 5.13 × 104 copies/mg of dust, 5.07 × 101 copies/mg, 9.98 EU/mg for total bacteria, Aspergillus/Penicillium and endotoxin concentrations, respectively. The main microorganisms were associated with human occupancy such as skin-related bacteria or yeasts, regardless of the type of ventilation.

Visual Outcomes after Vitrectomy for Terson Syndrome Secondary to Traumatic Brain Injury.

PURPOSE: To evaluate visual outcomes after vitrectomy for intraocular hemorrhages secondary to traumatic brain injury. DESIGN: Retrospective, observational case series. PARTICIPANTS: A total of 28 eyes in 20 patients undergoing vitrectomy for Terson syndrome secondary to traumatic brain injury between 1997 and 2015. METHODS: We reviewed the records of patients undergoing a standard 20-gauge or 23-gauge pars plana vitrectomy for intraocular hemorrhages secondary to traumatic brain injury, and the timing of vitrectomy in relation to the inciting intracranial event was recorded. MAIN OUTCOME MEASURES: The primary outcome measure was the change in the preoperative visual acuity score at postoperative month 1 and at the last noted clinic appointment. RESULTS: A total of 28 eyes in 20 patients (all male) underwent pars plana vitrectomy for intraocular hemorrhages secondary to traumatic brain injury. The mean preoperative baseline logarithm of the minimum angle of resolution (logMAR) (Snellen) best-corrected visual acuity (BCVA) was 1.81±0.56 (20/1290). At 1-month postoperative follow-up, the mean BCVA was 0.30±0.33 (20/40). At the date of the last follow-up, the mean BCVA was 0.15±0.24 (20/30) and the median BCVA was 0.00 (20/20). Although the difference between preoperative and postoperative BVCA was significantly different at 1 month and the final postoperative clinic visits (P < 0.001), there was not a correlation between preoperative visual acuity as a predictor of final postoperative visual acuity outcome (r=-0.32; P = 0.09; 95% confidence interval [CI] -0.62 - 0.06). At the date of the last follow-up, the differences in visual outcomes between the individuals undergoing vitrectomy within 3 months of the inciting event, 0.08±0.15 (20/25), were not significantly different than those undergoing surgical intervention after 3 months, 0.18±0.27 (20/30) (P = 0.28). Three cases among those undergoing vitrectomy after 3 months were complicated by retinal detachment, none of which resulted in a BCVA worse than when the patient originally presented preoperatively. CONCLUSIONS: In this retrospective series of patients without other ocular pathology, surgical intervention effectively provided rapid visual recovery in the majority of individuals with intraocular hemorrhages secondary to traumatic brain injury, irrespective of the timing of vitrectomy or of preoperative visual acuity.

Interaction of NO2 with hydrocarbon soot: focus on HONO yield, surface modification, and mechanism.

Using a coated-wall flow tube connected to a mass spectrometer, the heterogeneous conversion of NO2 to HONO on dry hydrocarbon soot surfaces has been studied at room temperature and 243 K. Particular attention was given to the measurement of the HONO yield as a function of hydrocarbon fuel, NO2 partial pressure, extent of uptake, and surface oxidation state. In all cases, the yield is invariant of these parameters and close to unity, indicative of an irreversible oxidation mechanism by which the NO2 abstracts an H atom from the surface. XPS analysis shows that the surface N content does not measurably increase with NO2 exposure. There is minimal surface reactivity regeneration with time or via exposure to high relative humidity. A BET surface area measurement of the entire soot film exposed to NO2 was used to determine the amount of HONO that can be generated from the soot surface per unit surface area, prior to its deactivation. The reduction of NO2 to HONO on soot is unlikely to account for the observed nighttime buildup of HONO in polluted urban environments.

Laboratory measurements of thermodynamics of adsorption of small aromatic gases to n-hexane soot surfaces.

The adsorption isotherms of a series of aromatic hydrocarbons on n-hexane soot were measured as a function of temperature and partial pressure in a coated-wall flow tube coupled to an electron-impact mass spectrometer. The specific surface area was determined for each of the samples by measuring the BET isotherm of Kr at 77 K. The gas-to-surface uptakes were fully reversible with the extent of adsorption increasing with decreasing temperature and increasing partial pressures. At low partial pressures, the isotherms were well modeled by the Langmuir isotherm for all experimental conditions, and the adsorption was found to saturate at one monolayer of coverage at approximately 2 x 10(14) molecule cm(-2). For the less volatile species, evidence for multilayer adsorption was observed and the BET isotherm was used instead. The experimental enthalpies of adsorption were consistently higher than the enthalpies of vaporization for all compounds. A linear free-energy relationship was developed between the Langmuir equilibrium constant for adsorption and the compound's (sub-cooled) liquid vapor pressure, providing validation for the use of such relationships in assessing gas-particle partitioning of aromatic hydrocarbons to soot aerosols in the environment. The experimental results were compared to the Junge-Pankow gas-to-aerosol partitioning model.