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Accessibility of emergency medical care is one of the crucial factors in evaluating national primary medical care systems. While many studies have focused on this issue, there was a fundamental limit to the measurement of accessibility of emergency rooms, because the commonly used census-based population data are difficult to provide realistic information in terms of time and space. In this study, we evaluated the geographical accessibility of emergency rooms in South Korea by using dynamic population counts from mobile phone data. Such population counts were more accurate and up-to-date because they are obtained by aggregating the number of mobile phone users in a 50-by-50 m grid of a locational field, weighted by stay time. Considering both supply and demand of emergency rooms, the 2-step floating catchment analysis was implemented. As a result, urban areas, including the capital city Seoul, showed lower accessibility to emergency rooms, whereas rural areas recorded higher accessibility. This result was contrary to the results analyzed by us based on census-based population data: higher accessibility in urban areas and lower in rural. This implies that using solely census data for accessibility analysis could lead to certain errors, and adopting mobile-based population data would represent the real-world situations for solving problems of social inequity in primary medical care. [ABSTRACT FROM AUTHOR]

The characteristics of springtime aerosols, including their optical and microphysical properties, were analyzed for the months of March to May of 2009 in Gwangju (35.23°N, 126.84°E), Korea. A high Light Detection and Ranging (LIDAR)-derived aerosol depolarization ratio (δ) of 0.25 ± 0.04 was determined on dust particles during the observation period. The Ångström exponent values of the 440–870 nm wavelength pair (Å 440–870 ) and single-scattering albedo at 675 nm (Ω 675 ) measured by a CIMEL sun/sky radiometer were 0.77 ± 0.19 and 0.95 ± 0.01, respectively. The elevated dust layers reached a maximum elevation of 4 km above sea level. Anthropogenic/smoke particles that originated from highly populated/industrialized regions could be distinguished by their relatively smaller particle size (Å 440–870 ranged between 1.33 and 1.36) and higher light-absorbing (Ω 675 of 0.92 ± 0.01) characteristics. These aerosols are mostly distributed at altitudes < 1.2 km. The root-mean-square deviation (RMSD) between the aerosol optical depth (AOD, τ) derived from LIDAR (τ LIDAR ) and from the CIMEL sun/sky radiometer (τ CIMEL ) varied with respect to the surface PM 10 concentration. The RMSD between τ LIDAR and τ CIMEL was as low as 13% under lower PM 10 concentration levels (< 100 μg/m 3 ). In contrast, the RMSD between τ LIDAR and τ CIMEL increased three times (~ 31%) under high surface PM 10 concentration levels (> 100 μg/m 3 ). These results suggest that the accuracy of τ LIDAR is influenced by specific atmospheric conditions, regardless of its uncertainty. [ABSTRACT FROM AUTHOR]