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High Altitude Pulmonary Edema (HAPE) seriously threatens the health of people at high altitudes. There are drug treatments for HAPE, and dry powder formulations (DPFs) represent a rapid and accessible delivery vehicle for these drugs. However, there are presently no reports on the inhalability of DPFs in low-pressure environments. Given the reduced atmospheric pressure typical at high altitudes, conventional DPFs might not be suitable for inhalation. Therefore, it is necessary to elucidate the deposition behaviors of dry powder in the respiratory tract at low pressure, as well as to improve their pulmonary deposition efficiency via adjustments to their formulation and design. The effect of air pressure, inspiratory velocity, and particle properties (such as size, density, and aerodynamic diameter) on pulmonary deposition of DPFs was calculated by a computational fluid dynamics (CFD)-coupled discrete phase model. DPFs of various aerodynamic diameters were prepared by spray drying, and the inhalability of these DPFs in a low-pressure environment was evaluated in mice. Finally, a mouse model of HAPE was established, and the treatment of HAPE by nifedipine-loaded DPFs with small aerodynamic diameter was validated. CFD results showed that low pressure decreased the deposition of DPFs in the lungs. At 0.5 standard atmosphere, DPFs with aerodynamic diameter of ∼2.0 μm could not enter the lower respiratory tract; however, a decrease in the physical diameter, density, and, consequently, the aerodynamic diameter of the DPFs was able to enhance pulmonary deposition of these powders. To validate the CFD results, three kinds of dry powder with aerodynamic diameters of 0.66, 0.98, and 2.00 μm were prepared by spray drying. Powders with smaller aerodynamic diameter could be inhaled into the lungs of mice more effectively, and, consequently could ameliorate the progression of HAPE more effectively than conventional powders. These results were consistent with the CFD results. Low atmospheric pressure can prevent the pulmonary deposition of DPFs at high altitudes. Compared with conventional DPFs, powders with smaller aerodynamic diameter can be effectively inhaled at these pressures and thus might be more suitable for the treatment the HAPE. [ABSTRACT FROM AUTHOR]

An Assessment of PM2.5 at Oluku dumpsite and selected residential buildings was investigated in Ovia North East local government in Benin City, Edo state Nigeria using a portable hand-held digital anemometer (BTMETER 100) and air quality monitor (L529K). Data obtained gives the mean values of PM2.5 range of 36.20-45.50 μg/m³ and 58.17-393.82 μg/m³ for wet and dry season respectively, which shows significant difference in spatial and seasonal distribution of PM2.5 (p< 0.05) in the study area and control stations. Further findings revealed that concentration PM2.5 in both seasons and sampling locations exceeded the WHO and USEPA Limits of 25 μg/m³and 35 μg/m³ respectively with the exception of the control (GAQC) location during wet season. [ABSTRACT FROM AUTHOR]

An Assessment of PM2.5 at Oluku dumpsite and selected residential buildings was investigated in Ovia North East local government in Benin City, Edo state Nigeria using a portable hand-held digital anemometer (BTMETER 100) and air quality monitor (L529K). Data obtained gives the mean values of PM2.5 range of 36.20-45.50 µg/m3and 58.17–393.82 µg/m3 for wet and dry season respectively, which shows significant difference in spatial and seasonal distribution of PM2.5 (p ) in the study area and control stations. Further findings revealed that concentration PM2.5 in both seasons and sampling locations exceeded the WHO and USEPA Limits of 25 µg/m3and 35 µg/m3 respectively with the exception of the control (GAQC) location during wet season.

Particle size measurement of aerosolized particles from orally inhaled and nasal drug products (OINDPs) can be used to assess the likely deposition distribution in the human respiratory tract (HRT). Size is normally expressed in terms of aerodynamic diameter, since this scale directly relates to the mechanics of particle transport from inhaler to deposition locations. The multistage cascade impactor (CI) is the principal apparatus used to size fractionate aerosols in terms of their aerodynamic particle size distributions (APSDs). Clinically meaningful metrics, such as fine and coarse particle mass fractions, can be determined from the cumulative mass-weighted APSD. In effective data analysis (EDA), CI data are reduced to small and large particle mass. The sum and ratio of these metrics are used to characterize impactor-sized mass, without the need for stage groupings or other APSD interpretation. Aerosol characterization by full-resolution CI is complex, and so, an abbreviated impactor measurement has recently come to prominence. Here, multiple stages of the CI are reduced to just one or two size fractionating stages so that measures of fine (and extrafine) particle mass from a two-stage system can be directly determined without the need to group the mass of active pharmaceutical ingredient (API) on adjacent stages. Time-of-flight-based methods determine APSD more rapidly but require refinements such as single-particle mass spectroscopy to relate size measurements to API content. Alternatives for size characterizing OINDP aerosols are few; laser diffractometry is by far the most important, especially for nasal sprays and solution-based orally inhaled formulations in which there is no confounding of data from suspended excipient(s). Laser-phase Doppler anemometry (L-PDA) has also been shown to be useful for nasal sprays. If aerodynamic size-related information is not a priority, optical microscopy combined with Raman chemical imaging offers prospects for separate determination of API components in combination product-generated aerosols. [ABSTRACT FROM AUTHOR]

Understanding the transport and deposition of fibers in the respiratory airway is of great significance for the exposure assessment to non-spherical contaminants. Due to its complexity, few computational studies physically resolved the fibers' coupled translational and rotational motion in investigating fiber transport behaviors in the 3D human nasal airways. Additional studies are needed to fully understand the role of the fiber lengths in nasal deposition and the practical benchmarking of fiber characterization to its spherical equivalency. This study investigated the transport and deposition of fibrous particles in the human nasal cavity, resolving the coupled translational and rotational motion to fill the gap. For the first time, a detailed single fiber trajectory in the 3D nasal chamber, accounting for the coupled translational and rotational movement, was visually presented. The subtle effects of fiber deposition due to fiber lengths, rotation, and interaction with the local flow stream, were revealed and analyzed. Furthermore, the study identified the relationship between microfiber deposition and fiber lengths in the human nasal cavity. In particular, nasal deposition of the fibrous and spherical particles with the same impaction parameter or aerodynamic diameter was compared and discussed. The study led to the findings that fiber lengths play different roles in affecting the transport and deposition of microfibers in the human nasal cavity. The relative deposition level between elongated fibers and the spherical particles varies depending on the impaction parameter or the aerodynamic diameter. Current findings are well supported by the literature data. • The transport and deposition of microfibers in human nasal cavity was investigated. • Effects on fiber deposition due to fiber lengths and rotation were analyzed. • Nasal deposition of the fibrous and spherical particles were compared. • Both fibers' diameter and length affect the nasal transport and deposition. • Fiber length might play different roles in three identifiable regions for deposition. [ABSTRACT FROM AUTHOR]

Aerosols play crucial roles in affecting air quality, climate and human health. Particle morphology and density would provide critical information on the chemical composition, mixing state and aging process of particles. Many investigations used dynamic shape factor (χ) to quantify particle shape. However, the measurement for χ often requires the knowledge of particle density, which is usually not readily available for atmospheric aerosols. Besides, χ is not a pure geometric descriptor, as it is also dependent on Knudsen number (K n). Here, a method, consisting of an aerodynamic aerosol classifier (AAC, aerodynamic particle diameter, D a , measurement), a differential mobility analyzer (DMA, electrical mobility particle diameter, D m , measurement) and a single particle aerosol mass spectrometer (SPAMS, vacuum aerodynamic particle diameter, D v a , measurement), was developed to investigate two geometric descriptors that are solely dependent on particle geometry: the orientationally averaged projected area (A P) and the hydrodynamic radius (R H). The shape indicator, S , was defined as the square root of the ratio A P / π R H 2. To test the performance of the AAC-DMA-SPAMS system, the S and χ of 9 types of laboratory-generated particles with known density were measured with this system, and the quantitative relationship between χ (1< χ <1.05) and S (1< S <1.5) was established at room temperature (T≈300K) and ambient condition. Finally, this method was applied to investigate the S of ambient aerosols in an urban area. A significant fraction of near-spherical aerosols was observed. Thus, their densities can be calculated. Generally, the AAC-DMA-SPAMS system can provide shape, density and the mass spectral information of ambient particle, which can help elucidate their mixing state and aging processes. • A method that can measure shape indicator (S), density and mass spectra of less irregular particles (S < 1.5) was developed. • The quantitative relation between shape indicator (S) and dynamic shape factor (χ) was established at ambient condition. • A significant fraction of urban ambient aerosols was near-spherical, thus their densities can be readily obtained. [ABSTRACT FROM AUTHOR]