Ground-based measurements of immersion freezing in the eastern Mediterranean

Ice nuclei were measured in immersion-freezing mode in the eastern Mediterranean region using the FRIDGE-TAU (FRankfurt Ice-nuclei Deposition freezinG Experiment, the Tel Aviv University version) chamber. Aerosol particles were sampled during dust storms and on clean and polluted days (e.g., Lag BaOmer). The aerosol immersion-freezing potential was analyzed in the laboratory using a drop-freezing method. Droplets from all the samples were found to freeze between −11.8 °C and −28.9 °C. Immersion-freezing nuclei (FN) concentrations range between 0.16 L⁻¹ and 234 L⁻¹, while the activated fraction (AF) ranges between 8.7 × 10^&minus;8 and 4.9 × 10^&minus;4. The median temperature at which the drops from each filter froze was found to be correlated with the corresponding daily average of PM₁₀, PM_2.5 and PM₁₀–PM_2.5. A higher correlation value between FN concentrations and PM₁₀–PM_2.5 suggests that the larger particles are generally more effective as FN. <br><br> The measurements were divided into dust storms and "clean" conditions (this is a relative term, because dust particles are always present in the atmosphere is this region) based on the air mass back trajectories and the aerosol mass concentrations (PM₁₀). Droplets containing ambient particles from dust storm days froze at higher temperatures than droplets containing particles from clean days. Statistically significant differences were found between dust storms and clean conditions primarily in terms of the initial temperature at which the first drops froze, the median freezing temperature and the aerosol loading (PM values). FN concentrations and AF values in dust storms were larger by more than a factor of 2 than in the clean conditions. This observation agrees with previous studies showing that some dust particles are almost always present in the atmosphere in this region. <br><br> Measurements of aerosol particles emitted from wood burning bonfires during a Lag BaOmer holiday showed that although a high concentration of particles was emitted, those particles' effectiveness as FN was relatively poor. The most likely reason for the low FN efficiency is the combination of relatively low fire temperatures and high organic carbon fraction in the aerosols

The study of atmospheric ice-nucleating particles via microfluidically generated droplets

Ice-nucleating particles (INPs) play a significant role in the climate and hydrological cycle by triggering ice formation in supercooled clouds, thereby causing precipitation and affecting cloud lifetimes and their radiative properties. However, despite their importance, INP often comprise only 1 in 10³–10⁶ ambient particles, making it difficult to ascertain and predict their type, source, and concentration. The typical techniques for quantifying INP concentrations tend to be highly labour-intensive, suffer from poor time resolution, or are limited in sensitivity to low concentrations. Here, we present the application of microfluidic devices to the study of atmospheric INPs via the simple and rapid production of monodisperse droplets and their subsequent freezing on a cold stage. This device offers the potential for the testing of INP concentrations in aqueous samples with high sensitivity and high counting statistics. Various INPs were tested for validation of the platform, including mineral dust and biological species, with results compared to literature values. We also describe a methodology for sampling atmospheric aerosol in a manner that minimises sampling biases and which is compatible with the microfluidic device. We present results for INP concentrations in air sampled during two field campaigns: (1) from a rural location in the UK and (2) during the UK’s annual Bonfire Night festival. These initial results will provide a route for deployment of the microfluidic platform for the study and quantification of INPs in upcoming field campaigns around the globe, while providing a benchmark for future lab-on-a-chip-based INP studies

Dust Under the Radar: Rethinking How to Evaluate the Impacts of Dust Events on Air Quality in the United States

Abstract Dust is an important and complex constituent of the atmospheric system, having significant impacts on the environment, climate, air quality, and human health. Although dust events are common across many regions of the United States, their impacts are not often prioritized in air quality mitigation strategies. We argue that there are at least three factors that result in underestimation of the social and environmental impact of dust events, making them receive less attention. These include (a) sparse monitoring stations with irregular spatial distribution in dust‐influenced regions, (b) inconsistency with dust sampling methods, and (c) sampling frequency and schedules, which can lead to missed dust events or underestimation of dust particle concentrations. Without addressing these three factors, it is challenging to characterize and understand the full air quality impacts of dust events in the United States. This paper highlights the need for additional monitoring to measure these events so that we can more fully evaluate and understand their impacts, as they are predicted to increase with climate change

Laboratory studies of collection efficiency of sub-micrometer aerosol particles by cloud droplets on a single-droplet basis

An experimental setup has been constructed to measure the collection efficiency (CE) of sub-micrometer aerosol particles by cloud droplets. Droplets of a dilute aqueous ammonium sulfate solution with an average radius of 21.6 μm fall freely into a chamber and collide with sub-micrometer polystyrene latex (PSL) sphere particles of known sizes and concentrations. Two relative humidity (RH) conditions, 15 ± 3 % and 88 ± 3 %, hereafter termed "low" and "high", respectively, were varied with different particles sizes and concentrations. After passing through the chamber, the droplets and aerosol particles were sent to the Particle Analysis by Laser Mass Spectrometry (PALMS) instrument to determine chemical compositions on a single-droplet basis. "Coagulated droplets" (droplets that collected aerosols) had mass spectra that contained signatures from both an aerosol particle and a droplet residual. CE values range from 2.0 × 10⁻¹ to 1.6 for the low-RH case and from 1.5 × 10⁻² to 9.0 × 10⁻² for the high-RH case. CE values were, within experimental uncertainty, independent of the aerosol concentrations. CE values in this study were found to be in agreement with previous experimental and theoretical studies. To our knowledge, this is the first collection experiment performed on a single-droplet basis with atmospherically relevant conditions such as droplet sizes, droplet charges and flow

When a Dust Storm Is Not a Dust Storm: Reliability of Dust Records From the Storm Events Database and Implications for Geohealth Applications

Abstract Windblown dust impacts human health, air quality, and climate. The National Weather Service Storm Events Database (SED) is a widely used dataset of significant or unusual weather, including dust storms (DS), and resulting deaths, injuries, and material losses in the USA. The SED is frequently used by medical, social, and atmospheric scientists. However, it is uncertain whether this dataset reliably represents spatial and temporal variations and trends of DS. Analyzing the SED from 2000 to 2020 identified 1,167 DS reports; removing reports of the same event from multiple locations left 647 DS in 21 USA states. The number of DS ranged from 12 in 2008 to 53 in 2018, with no strong interannual trends detected (R2 was 0.3). By examining the DS events reported in the SED based on meteorological observations including wind speed, visibility, and weather codes, we determined that the SED was not only missing many DS (visibility 1 km and were incorrectly reported as DS. Underrepresentation of DS and inclusion of BLDU may be partially due to the diverse sources contributing to the SED and a lack of verification of the reports and their consistency. Although the SED is an extremely useful and valuable database of impactful weather, including DS, the issues found in this study warrant caution in use of this dataset for many geohealth applications

Neuvolatyöntekijöiden valmiudet ja toiminta infektiopositiivisen äidin hoidossa ja hoitokäytäntöjen toteutuminen

Raskaudenaikaisia infektioseulontoja on toteutettu Suomessa rutiininomaisesti 1950-luvulta lähti-en, ja nykyään ohjelma sisältää HIV-, kuppa- ja hepatiitti B –infektioiden seulonnan. Näiden infek-tioiden aiheuttama lapsen terveyttä uhkaava tauti voidaan tehokkaasti torjua ohjeiden mukaisella hoidolla. Raskaudenaikainen infektioseulonta on periaatteessa tehokas ja hyvin hoidossa koko maassa, mutta seulonnan vaikuttavuudesta ja hoitokäytännöistä yleensä tai hoitokäytäntöjen yh-teneväisyydestä ei kuitenkaan ole valtakunnallista tietoa. Tämän tutkimuksen tarkoituksena oli selvittää raskaudenaikana todettujen infektioiden olemassa olevien ohjeiden mukaisten hoitokäytäntöjen toteutumista ja arvioida positiivisen infektiolöydök-sen aiheuttamaa lisätyötä neuvolassa. Tutkimuksen tavoite on tuottaa tietoa, joka on hyödynnet-tävissä päivittäessä ja yhtenäistäessä valtakunnallisia ohjeistuksia ja suosituksia. Tutkimus oli määrällinen- eli kvantitatiivinen rekisteritutkimus, jossa olivat mukana kaikki vuosina 2005–2009 Terveyden ja hyvinvoinninlaitoksen (THL) infektioseulonnoissa positiivisen tuloksen saaneet äidit, sekä näistä raskauksista syntyneet lapset. Tutkimuksen rekisteriaineisto käsittää potilasasiakirjoista kerättyjä tietoja täydennettynä THL:n Neuvolaserologian laboratorion FMC (Finnish Maternity Cohort) seerumipankin tietoja, syntyneiden lasten- (BR Birth Register) ja hoi-toilmoitusrekisterin (Hilmo-rekisteri) tietoja. Lisäksi tutkimusaineistoon sisältyy Webropol-kyselytutkimuksen vastaukset. Kaikista tutkimukseen kuuluvista henkilöistä, joilla infektioseulon-tavaiheessa oli virallinen henkilötunnus, on kattavat FMC-, BR- ja Hilmo-rekistereistä kootut ter-veystiedot. Potilasasiakirja- ja rekisteritiedot saatiin 497 (65 %) äidistä ja lapsesta ja ne jäivät puuttumaan 120 (16 %) äidiltä ja lapselta. Webropol-kyselytutkimuksen vastauksia saatiin 137/200 äitiysneuvolatyöntekijältä eli vastausprosentti oli suhteellisen hyvä, 68.5 %. Tutkimustuloksien perusteella raskaudenaikaisten infektioiden hoidosta ei ole selkeitä valtakun-nallisia ohjeita. Neuvolan työntekijät etsivät eri lähteitä käyttäen hoito-ohjeita. Tutkimuksista selvi-si, että hepatiitti B -positiivisten naisten lapset saivat sairaalassa suositusten mukaisen immuno-globuliinin sekä ensimmäisen hepatiitti B -rokotteen. Tehosterokotteiden saannissa oli aineiston perusteella puutteellisuuksia. HIV-positiivisten naisten seuranta toteutuu pääasiassa erikoissai-raanhoidossa. Näiden naisten lapsista kaikki saivat ennaltaehkäisevän HIV- lääkityksen synty-män jälkeen. Tietoja yhdistämällä todetaan että kuppa-infektion hoito jää toteutumatta jopa noin puolella tapauksia, jotka voimassa olevien Käypä Hoito-suositusten mukaan tulisi hoitaa.The infection screening program for pregnant women in Finland includes tests for HIV, syphilis and hepatitis B. The diseases these infections cause for the baby can effectively be treated fol-lowing the instructions available. Although the screening program is well executed, there are no national statistics on the effectiveness of the screenings, the treatment practices used or the con-sistency of the treatment practices. The aim of this study is to find out how the treatment of infections found during pregnancy is car-ried out and to evaluate the amount of extra work the infection findings cause for the maternity clinic personnel. The study aims at producing information that can be utilized when updating and unifying the national instructions and recommendations. The study was carried out as a quantitative registry study, including all mothers who had been tested positive for infections in the screenings done in 2005-2009 by the National Institute of Health and Welfare (THL), as well as their children born from these pregnancies. The data com-prised of patient file data supplemented with the THL FMC (Finnish Maternity Cohort) serum bank data, the BR (Birth Register) data and information collected from the care register Hilmo. In addi-tion, the data included the replies to the Webropol questionnaire-based study. The patient case file and registry information was received on 497 mothers and children (65%) and they were missing on 120 mothers and children (16%). 137/200 Webropol responses were received from the maternity clinic personnel (response rate 68,5%). Findings revealed that there are no national instructions for the treatment of infections detected during pregnancy. The maternity clinic personnel searched treatment instructions from various sources. Findings also showed that the children of HBV positive women received immunoglobulin and their first HBV vaccination in the hospital, as recommended. Based on the data, there were inadequacies in getting the booster shots. The follow-up of HIV positive women is mainly carried out in specialized medical care facilities. All children of HIV positive women got preventive HIV medication after birth. Combination of various data revealed that as many as half of the syphilis infections requiring treatment according to the current nationanational recommendations are left without treatment

Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations

Ice-nucleating particles (INPs) are known to affect the amount of ice in mixed-phase clouds, thereby influencing many of their properties. The atmospheric INP concentration changes by orders of magnitude from terrestrial to marine environments, which typically contain much lower concentrations. Many modelling studies use parameterizations for heterogeneous ice nucleation and cloud ice processes that do not account for this difference because they were developed based on INP measurements made predominantly in terrestrial environments without considering the aerosol composition. Errors in the assumed INP concentration will influence the simulated amount of ice in mixed-phase clouds, leading to errors in top-of-atmosphere radiative flux and ultimately the climate sensitivity of the model. Here we develop a global model of INP concentrations relevant for mixed-phase clouds based on laboratory and field measurements of ice nucleation by K-feldspar (an ice-active component of desert dust) and marine organic aerosols (from sea spray). The simulated global distribution of INP concentrations based on these two species agrees much better with currently available ambient measurements than when INP concentrations are assumed to depend only on temperature or particle size. Underestimation of INP concentrations in some terrestrial locations may be due to the neglect of INPs from other terrestrial sources. Our model indicates that, on a monthly average basis, desert dusts dominate the contribution to the INP population over much of the world, but marine organics become increasingly important over remote oceans and they dominate over the Southern Ocean. However, day-to-day variability is important. Because desert dust aerosol tends to be sporadic, marine organic aerosols dominate the INP population on many days per month over much of the mid-and high-latitude Northern Hemisphere. This study advances our understanding of which aerosol species need to be included in order to adequately describe the global and regional distribution of INPs in models, which will guide ice nucleation researchers on where to focus future laboratory and field work