Wildfire and African dust aerosol oxidative potential, exposure and dose in the human respiratory tract.

Exposure to wildfire smoke and dust can severely affect air quality and health. Although particulate matter (PM) levels and exposure are well-established metrics linking to health outcomes, they do not consider differences in particle toxicity or deposition location in the respiratory tract (RT). Usage of the oxidative potential (OP) exposure may further shape our understanding on how different pollution events impact health. Towards this goal, we estimate the aerosol deposition rates, OP and resulting OP deposition rates in the RT for a typical adult Caucasian male residing in Athens, Greece. We focus on a period when African dust (1-3 of August 2021) and severe wildfires at the northern part of the Attika peninsula and the Evia island, Greece (4-18 of August 2021) affected air quality in Athens. During these periods, the aerosol levels increased twofold leading to exceedances of the World Health Organization (WHO) [15(5) µg m-3] PM10 (PM2.5) air quality standard by almost 100 %. We show that the OP exposure is 1.5-times larger during the wildfire smoke events than during the dust intrusion, even if the latter was present in higher mass loads - because wildfire smoke has a higher specific OP than dust. This result carries two important implications: OP exposure should be synergistically used with other metrics - such as PM levels - to efficiently link aerosol exposure with the resulting health effects, and, certain sources of air pollution (in our case, exposure to biomass burning smoke) may need to be preferentially controlled, whenever possible, owing to their disproportionate contribution to OP exposure and ability to penetrate deeper into the human RT.

Canadian Biomass Burning Aerosol Properties Modification during a Long-Ranged Event on August 2018.

The aim of this paper is to study the spatio-temporal evolution of a long-lasting Canadian biomass burning event that affected Europe in August 2018. The event produced biomass burning aerosol layers which were observed during their transport from Canada to Europe from the 16 to the 26 August 2018 using active remote sensing data from the space-borne system Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The total number of aerosol layers detected was 745 of which 42% were identified as pure biomass burning. The remaining 58% were attributed to smoke mixed with: polluted dust (34%), clean continental (10%), polluted continental (5%), desert dust (6%) or marine aerosols (3%). In this study, smoke layers, pure and mixed ones, were observed by the CALIPSO satellite from 0.8 and up to 9.6 km height above mean sea level (amsl.). The mean altitude of these layers was found between 2.1 and 5.2 km amsl. The Ångström exponent, relevant to the aerosol backscatter coefficient (532/1064 nm), ranged between 0.9 and 1.5, indicating aerosols of different sizes. The mean linear particle depolarization ratio at 532 nm for pure biomass burning aerosols was found equal to 0.05 ± 0.04, indicating near spherical aerosols. We also observed that, in case of no aerosol mixing, the sphericity of pure smoke aerosols does not change during the air mass transportation (0.05-0.06). On the contrary, when the smoke is mixed with dessert dust the mean linear particle depolarization ratio may reach values up to 0.20 ± 0.04, especially close to the African continent (Region 4).

Near-infrared fundus autofluorescence in early age-related macular degeneration.

PURPOSE: To describe the patterns on near-infrared fundus autofluorescence in eyes affected by early age-related macular degeneration. DESIGN: Cross-sectional observational case series. PARTICIPANTS: A total of 84 eyes of 84 patients suffering from early age-related macular degeneration (>63 µm but <125 µm drusen and no-to-mild retinal pigment epithelium abnormalities) were enrolled. METHODS: Patients underwent best-corrected visual acuity, biomicroscopy, infrared reflectance, short-wavelength fundus autofluorescence, and near-infrared fundus autofluorescence. Eyes were classified according to different patterns of near-infrared fundus autofluorescence. Main outcome was definition of relative prevalence and features of each near-infrared fundus autofluorescence pattern; secondary outcomes were correlation between near-infrared fundus autofluorescence and short-wavelength fundus autofluorescence and between near-infrared fundus autofluorescence patterns and best-corrected visual acuity. RESULTS: Four different patterns of near-infrared fundus autofluorescence identified: normal foveal signal (Pattern A, 7%); normal foveal signal with hyperautofluorescent/hypoautofluorescent spots not involving the fovea (Pattern B, 65.5%); hyperautofluorescent/hypoautofluorescent spots involving the fovea (Pattern C, 15.5%); patchy pattern (Pattern D, 12%). best-corrected visual acuity was lower in eyes with foveal signal alteration (Patterns C and D). CONCLUSION: Near-infrared fundus autofluorescence pattern in early age-related macular degeneration might be suggestive of visual function deterioration when the fovea is involved. Longitudinal studies are warranted to confirm our preliminary results.

Lidar algorithms and technique in 3D scanning for planetary boundary layer height and single-beam-single-pointing wind speed retrieval.

Planetary boundary layer height (PBLH) and wind speed measurement are most important to meteorology for accurate weather forecasting and also forecasting for personnel-human safety in public places such as airports, camps, cities, etc. According to the location of the measurements, weather phenomena can change PBLH and wind speed values in a small amount of time; and so, accurate measurement of those, especially in longer distances gathered with lower budgets, is most welcome from societies. Different techniques have been developed through the years in order to detect these parameters safely, with the most effective ones to be the expensive, radiosonde method for PBLH and the Doppler method for wind measurements, with in situ measurements. In this work, we present new algorithms and techniques, to the best of our knowledge, in order to provide PBLH with a single beam by a 3D lidar in vertical and slant pointing for wider areas measured in the sky and wind speed measurements in 2D and calculated 3D, from respected distances without any Doppler equipment on board. They are adjustable by the user in order to work automatically at any location and time of the year and at any pointing of the lidar's beam. "UNIFORM" technique, "METCON PBLH", "SIBESMEA", and "WIND METCON" algorithms can be found extremely helpful for airport tower controllers, atmospheric scientists, and the meteorological/remote sensing community, as well as for the "aviation and space" community via novel single-beam pointing measurement techniques.

Lidar algorithms in 3D scanning for atmospheric layering and planetary boundary layer height retrieval: comparison with other techniques: publisher's note.

This publisher's note amends the Funding section of Appl. Opt.57, 8199 (2018)APOPAI0003-693510.1364/AO.57.008199.

Lidar algorithms in 3D scanning for atmospheric layering and planetary boundary layer height retrieval: comparison with other techniques.

The planetary boundary layer height (PBLH), of great importance in meteorology and atmospheric physics, is strongly correlated with the geographical location, the solar irradiance, the seasonal variations, and the variability of the weather phenomena. So far, several lidar techniques have been developed to detect the PBLH, besides the radio soundings, sodars, or other techniques. In this work we propose new algorithms to provide the PBLH in near real time using a three-dimensional lidar in vertical or slant pointing. We show that the proposed variable space-time and vertical decision algorithms are able to estimate the PBLH under various meteorological conditions of more than 80% of the cases studied. Furthermore, these algorithms are user friendly (user adjustable), and they work automatically at any location and period of the year for any vertically/slant pointing lidar system. These algorithms are extremely helpful for meteorologists, airport tower controllers, and atmospheric scientists and in general for the remote sensing community.

Lidar algorithms for atmospheric slant range visibility, meteorological conditions detection, and atmospheric layering measurements.

Visibility at airports has to do, in many ways, with flight and ground safety. We present a novel method and algorithms based on lidar measurements and signal noise subtraction to provide atmospheric layering and estimated visibility values for tower controllers and meteorologists as well as from the pilot's point of view, according to the International Civil Aviation Organization and World Meteorological Organization requirements.

Acute central serous chorioretinopathy: a correlation study between fundus autofluorescence and spectral-domain OCT.

PURPOSE: To evaluate the correlation between fundus autofluorescence (FAF) and spectral-domain OCT (SD-OCT) morphological analysis in eyes with acute central serous chorioretinopathy (CSCR). METHODS: Thirty-one patients with a first episode of CSCR and symptom duration of less than 6 weeks were prospectively enrolled. FAF and SD-OCT examination were performed at baseline and at 2-month intervals. Main outcome measure was the correlation between FAF and SD-OCT retinal morphology. RESULTS: At baseline, 30/31 and 29/31 eyes showed a macular hypo-AF, corresponding to the neurosensory retinal detachment (SRD), on shortwave-FAF (SW-FAF) and near-infrared-FAF (NIR-FAF), respectively. While the SRD resolved, both FAF techniques showed a granular hyper-AF in 31 eyes. At first examination, SD-OCT confirmed the SRD with a photoreceptor outer-segment (OS) elongation in all cases. During SRD resolution, the photoreceptor layer appeared thicker and fragmented. Multiple hyper-reflective precipitates were detected in the outer plexiform and nuclear layer and between the photoreceptors and appeared colocalized with the hyper-AF dots composing the granular hyper-AF. After SRD resolution, the hypo-AF area reverted to a normal pattern on SW-FAF in all eyes and in 25/31 on NIR-FAF. Examination at 12 months showed that the granular hyper-AF was still detectable in 54 % eyes, whereas 6/31 eyes showed hypo-AF dots on NIR-FAF. On SD-OCT, the junction IS/OS was identifiable in 11/31 eyes soon after the SRD resolution and appeared completely restored in all patients at the final visit. CONCLUSION: The simultaneous acquisition of FAF and SD-OCT provides detailed findings of retinal abnormalities of CSCR and may help to understand the evolving process linked to CSCR.

Fluorescein angiography and spectral-domain optical coherence tomography for monitoring anti-VEGF therapy in myopic choroidal neovascularization.

AIM: To evaluate the agreement between fluorescein angiography (FA) and spectral-domain optical coherence tomography (SD-OCT) in detecting myopic choroidal neovascularization (CNV) activity during bevacizumab treatment. METHODS: Thirty-four patients with subfoveal myopic CNV were prospectively enrolled. FA and SD-OCT were performed at baseline and at all planned monthly visits. After the first injection, additional treatments were administered following detection of fluid on SD-OCT and/or leakage on FA. κ-Analysis was performed to examine the agreement between FA and SD-OCT. RESULTS: At baseline, FA and SD-OCT agreed in 26/34 cases (κ=0.23); sensitivity and specificity were 77.4 and 66.7%, respectively. Seven eyes presented leakage on FA with no fluid on SD-OCT, 1 case showed intraretinal fluid on SD-OCT and no leakage on FA. At the 1-month examination, specificity and κ-value improved, and 30/34 cases showed complete concordance. At the 3- and 4-month examinations, a discordance was noted in 6 cases. From the 5-month examination on, a correspondence was achieved in at least 30/34 cases and reached a perfect match in 11 sessions. CONCLUSIONS: Our study confirms the key role of FA in diagnosing myopic CNV. It seems possible there may be a role for SD-OCT in assisting FA to monitor the myopic CNV activity during anti-vascular endothelial growth factor antibody treatment.

Intravitreal ranibizumab for pigment epithelium detachment with subfoveal occult choroidal neovascularization: a prospective 24-month case series.

PURPOSE: To assess the effects of intravitreal ranibizumab injection in patients affected by pigment epithelial detachment associated with occult subfoveal choroidal neovascularization. DESIGN: Prospective, interventional case series. PARTICIPANTS: Forty eyes of 40 patients were considered for the purpose of the study. Consecutive patients were recruited for a 24-month study. All patients underwent a complete ophthalmic examination, including best-corrected visual acuity on Early Treatment Diabetic Retinopathy Study (ETDRS) charts. After a 3-monthly loading phase, further intravitreal ranibizumab injections were administered on the basis of detection of any type of fluid on optical coherence tomography. PRIMARY OUTCOME MEASURES: Changes in mean best-corrected visual acuity at 12 and 24 months and the proportion of eyes losing fewer than 15 letters (corresponding to 3 ETDRS lines) from baseline visual acuity. SECONDARY OUTCOME MEASURES: Changes in central macular thickness on optical coherence tomography and variation in mean area of the entire lesion. RESULTS: Forty patients were included. Mean best-corrected visual acuity decreased from 20/66 (58 ETDRS letters) to 20/83 (53 letters) at 12 months and 20/112 (489 ETDRS letters) at 24 months (P = .003). Eighty percent and 67.5% of eyes lost fewer than 3 lines at 12 and 24 months, respectively. Mean central macular thickness passed from 545 µm to 428 µm at 12 months and 426 µm at 24 months. Mean lesion area changed from 6826 µm(2) to 6312 µm(2) at 12 months and 6010 µm(2) at 24 months. CONCLUSIONS: The treatment of pigment epithelial detachment associated with occult subfoveal choroidal neovascularization with intravitreal ranibizumab injection after a 3-monthly loading phase and pro re nata strategy can lead to partial results over a 24-month follow-up. Further investigations are warranted to establish the best therapeutic approach to this disease.

Laser photocoagulation, photodynamic therapy, and intravitreal bevacizumab for the treatment of juxtafoveal choroidal neovascularization secondary to pathologic myopia.

OBJECTIVE: To compare the effects on visual acuity of laser treatment (LT), photodynamic therapy (PDT) with verteporfin, and intravitreal bevacizumab treatment in patients with juxtafoveal choroidal neovascularization secondary to pathologic myopia. METHODS: This prospective randomized clinical investigation enrolled 54 patients, who were divided into 3 groups receiving PDT, LT, or intravitreal bevacizumab treatment. The anti-vascular endothelial growth factor group received 1.25 mg of intravitreal bevacizumab at baseline; retreatment was performed if persistent intraretinal or subretinal fluid evaluated on optical coherence tomography or if choroidal neovascularization progression was detected on fluorescein angiography. The PDT group received treatment following the Verteporfin in Photodynamic Therapy Study Group guidelines. The LT group was submitted to direct LT and received PDT treatment if subfoveal recurrence or progression was detected on fluorescein angiography. A change in best-corrected visual acuity was the primary outcome. RESULTS: The mean best-corrected visual acuity in the PDT group decreased from 0.52 logMAR (SD, 0.24 logMAR) at baseline to 0.72 logMAR (SD, 0.25 logMAR) at the end of the study (P = .002). The LT group showed substantial stabilization from mean baseline visual acuity (mean, 0.45 logMAR [SD, 0.27 logMAR]) to the 24-month (mean, 0.56 logMAR [SD, 0.34 logMAR) examination values. The mean best-corrected visual acuity in the anti-vascular endothelial growth factor group increased from 0.6 logMAR (SD, 0.3 logMAR) at baseline to 0.42 logMAR (SD, 0.35 logMAR) at the end of the study (P = .006). CONCLUSIONS: Overall, bevacizumab treatment offers the best functional results during a 2-year follow-up. In view of the small size of the sample in this study and the relatively low frequency of juxtafoveal choroidal neovascularization secondary to pathologic myopia, a multicentric clinical trial is necessary to validate our results.

Aerosol lidar intercomparison in the framework of the EARLINET project. 3. Raman lidar algorithm for aerosol extinction, backscatter, and lidar ratio.

An intercomparison of the algorithms used to retrieve aerosol extinction and backscatter starting from Raman lidar signals has been performed by 11 groups of lidar scientists involved in the European Aerosol Research Lidar Network (EARLINET). This intercomparison is part of an extended quality assurance program performed on aerosol lidars in the EARLINET. Lidar instruments and aerosol backscatter algorithms were tested separately. The Raman lidar algorithms were tested by use of synthetic lidar data, simulated at 355, 532, 386, and 607 nm, with realistic experimental and atmospheric conditions taken into account. The intercomparison demonstrates that the data-handling procedures used by all the lidar groups provide satisfactory results. Extinction profiles show mean deviations from the correct solution within 10% in the planetary boundary layer (PBL), and backscatter profiles, retrieved by use of algorithms based on the combined Raman elastic-backscatter lidar technique, show mean deviations from solutions within 20% up to 2 km. The intercomparison was also carried out for the lidar ratio and produced profiles that show a mean deviation from the solution within 20% in the PBL. The mean value of this parameter was also calculated within a lofted aerosol layer at higher altitudes that is representative of typical layers related to special events such as Saharan dust outbreaks, forest fires, and volcanic eruptions. Here deviations were within 15%.

Aerosol lidar intercomparison in the framework of the EARLINET project. 2. Aerosol backscatter algorithms.

An intercomparison of aerosol backscatter lidar algorithms was performed in 2001 within the framework of the European Aerosol Research Lidar Network to Establish an Aerosol Climatology (EARLINET). The objective of this research was to test the correctness of the algorithms and the influence of the lidar ratio used by the various lidar teams involved in the EARLINET for calculation of backscatter-coefficient profiles from the lidar signals. The exercise consisted of processing synthetic lidar signals of various degrees of difficulty. One of these profiles contained height-dependent lidar ratios to test the vertical influence of those profiles on the various retrieval algorithms. Furthermore, a realistic incomplete overlap of laser beam and receiver field of view was introduced to remind the teams to take great care in the nearest range to the lidar. The intercomparison was performed in three stages with increasing knowledge on the input parameters. First, only the lidar signals were distributed; this is the most realistic stage. Afterward the lidar ratio profiles and the reference values at calibration height were provided. The unknown height-dependent lidar ratio had the largest influence on the retrieval, whereas the unknown reference value was of minor importance. These results show the necessity of making additional independent measurements, which can provide us with a suitable approximation of the lidar ratio. The final stage proves in general, that the data evaluation schemes of the different groups of lidar systems work well.

Analysis of the receiver response for a noncoaxial lidar system with fiber-optic output.

The return signal of a noncoaxial lidar system with fiber-optic output is examined. The dependence of the overlap regions and the overlap factor of the system on the fiber diameter is calculated for several inclination angles between the laser beam and the optical receiver axes. The effect of central obstruction is included and both cases of Gaussian and quasi-Gaussian laser beam profiles are treated. The irradiance spatial distribution on the focal plane of the system is calculated and experimentally determined. Finally, an alignment procedure of the lidar system is described based on the comparison between the range-corrected lidar signal and the range-corrected exponentially attenuated Rayleigh backscattered coefficient.