Suburban Site Research Articles

Comparative analysis for the impacts of VOC subgroups and atmospheric oxidation capacity on O3 based on different observation-based methods at a suburban site in the North China Plain

The persistent O3 pollution in the Beijing-Tianjin-Hebei (BTH) region remains unresolved, largely due to limited comprehension of O3-precursor relationship and photochemistry drivers. In this work, intraday O3 sensitivity evolution from VOC-limited (volatile organic compound) regime in the forenoon to transition regime in the late afternoon was inferred by relative incremental reactivity (RIR) in summer 2019 at Xianghe, a suburban site in BTH region, suggesting that VOC-focused control policy could combine with stringent afternoon NOx control. Then detailed impacts of VOC subgroups on O3 formation were further comprehensively quantified by parametric OH reactivity (KOH), O3 formation potential (OFP), as well as RIR weighted value and O3 formation path tracing (OFPT) approach based on photochemical box model. O3 episode days corresponded to stronger O3 formation, depicted by higher KOH (10.4 s−1), OFP (331.7 μg m−3), RIR weighted value (1.2), and F(O3)-OFPT (15.5 ppbv h−1). High proportions of isoprene and OVOCs (oxygenated VOCs) to the total KOH and the OFPT method were demonstrated whereas results of OFP and RIR-weighted presented extra great impacts of aromatics on O3 formation. The OFPT approach captured the process that has already happened and included final O3 response to the original VOC, thus reliable for replicating VOC impacts. The comparison results of the four methods showed similarities when utilizing KOH and OFPT methods, which reveals that the potential applicability of simple KOH for contingency VOC control and more complex OFPT method for detailed VOC- and source-oriented control during policy-making. To investigate propulsion of VOC-involved O3 photochemistry, atmospheric oxidation capacity (AOC) was quantified by two atmospheric oxidation indexes (AOI). Both AOIp_G (7.0 × 107 molec cm−3 s−1, potential AOC calculated by oxidation reaction rates) and AOIe_G (8.5 μmol m−3, estimated AOC given redox electron transfer for oxidation products) were stronger on O3 episode days, indicating that AOC promoted the radical cycling initiated from VOC oxidation and subsequent O3 production. Result-oriented AOIe_G reasonably characterized actual AOC inferred by good linear correlation between AOIe_G and O3 concentrations compared to process-oriented AOIp_G. Therefore, with continuous NOx abatement, AOIe_G should be considered to represent actual AOC, also O3-inducing ability.

Variation in urban snow quality indicated by three seasonal sampling surveys conducted in Luleå (Sweden) within a span of 27 years

Concentrations of total suspended solids (TSS), trace metals (Cu, Cd, Cr, Zn, Cd, Pb), Na and 16 US EPA priority PAHs in urban snow were studied in the City of Luleå in Northern Sweden. Snow was sampled at six central urban and suburban sites with various traffic intensities, in three sampling surveys (1994–95, 2002–03, 2020–21), repeated for three ages of the urban snow cover of 40, 80, and 120 days, respectively. The older data, from the 1994–95 and 2002–03 surveys, were obtained from the existing literature. The concentrations and mass loads of TSS and most trace metals studied (Zn, Cu, Pb, and Cd) varied with time. TSS, Zn, and Cu showed slightly higher concentrations and mass loads in the 2003 (TSS avg = 2300 μg/L, Zn avg = 620 μg/L and Cu avg = 250 μg/L) and 2021 (TSS avg = 1500 μg/L, Zn avg = 530 μg/L and Cu avg = 220 μg/L) sampling surveys, compared to the 1995 survey (TSS avg = 620 μg/L, Zn avg = 240 μg/L and Cu avg = 97 μg/L). However, no evident trend was observed between the 2003 and 2021 sampling surveys. The highest concentrations of Pb and Cd were observed in snow samples from the 1994–95 sampling survey (Pb max = 570 μg/L, Cd max = 4.6 μg/L). Results indicated higher concentrations of the pollutants studied in the city centre, compared to the residential suburbs, and in areas with heavier traffic, where concentrations of metals correlated well with traffic intensity. Fractionation analysis of trace metals indicated that Zn, Cu and Pb occurred mostly in the particulate-bound phase (>0.45 μm) containing the most of Zn, Cu, and Pb mass, at 80, 84 and 94% of the total, respectively. Over 50% of the dissolved phase of Zn and Cu was in the truly dissolved fraction (<3000 MWCO). Concentrations of PAHs also increased with traffic intensity, with pyrene being the most frequently detected PAH, likely because of the strength of sources and various physical processes influencing the snowbanks development and causing spatial and temporal variations in pollutant concentrations.

Prediction of the Concentration and Source Contributions of PM2.5 and Gas-Phase Pollutants in an Urban Area with the SmartAQ Forecasting System

The SmartAQ (Smart Air Quality) forecasting system produces high-resolution (1 × 1 km2) air quality predictions in an urban area for the next three days using advanced chemical transport modeling. In this study, we evaluated the SmartAQ performance for the urban area of Patras, Greece, for four months (July 2021, September 2021, December 2021, and March 2022), covering all seasons. In this work, we assess the system’s ability to forecast PM2.5 levels and the major gas-phase pollutants during periods with different meteorological conditions and local emissions, but also in areas of the city with different characteristics (urban, suburban, and background sites). We take advantage of this SmartAQ application to also quantify the main sources of the pollutants at each site. During the summertime, PM2.5 model performance was excellent (Fbias &lt; 15%, Ferror &lt; 30%) for all sites both in the city center and suburbs. For the city center, the model reproduced well (MB = −0.9 μg m−3, ME = 2.5 μg m−3) the overall measured PM2.5 behavior and the high nighttime peaks due to cooking activity, as well as the transported PM pollution in the suburbs. During the fall, the SmartAQ PM2.5 performance was good (Fbias &lt; 42%, Ferror &lt; 45%) for the city center and the suburban core, while it was average (Fbias &lt; 50%, Ferror &lt; 54%, MB, ME &lt; 3.3 μg m−3) for the suburbs because the model overpredicted the long-range transport of pollution. For wintertime, the system reproduced well (MB = −2 μg m−3, ME = 6.5 μg m−3) the PM2.5 concentration in the high-biomass-burning emission area with an excellent model performance (Fbias = −4%, Ferror = 33%) and reproduced well (MB &lt; 1.1 μg m−3, ME &lt; 3 μg m−3) the background PM2.5 levels. SmartAQ reproduced well the PM2.5 concentrations in the urban and suburban core during the spring (Fbias &lt; 40%, Ferror &lt; 50%, MB &lt; 8.5 μg m−3, ME &lt; 10 μg m−3), while it tended to slightly overestimate the regional pollution. The main local source of fine PM during summer and autumn was cooking, but most of the PM was transported to the city. Residential biomass burning was the dominant particle source of pollution during winter and early spring. For gas-phase pollutants, the system reproduced well the daily nitrogen oxides (NOx) concentrations during the summertime. Predicted NOx concentrations during the winter were consistent with measurements at night but underestimated the observations during the rest of the day. SmartAQ achieved the US EPA modeling goals for hourly O3 concentrations indicating good model performance.

Long-Range Atmospheric Mercury Transport from Across East Asia to a Suburban Coastal Area in Southern Vietnam.

Exports of atmospheric mercury (Hg) from continental East Asia, a major Hg emitter in the globe, have been reported by several studies in neighboring countries such as Japan and Korea. Nonetheless, studies concerning this topic in Southeast Asia (SEA) countries are still limited. Accordingly, gaseous elemental mercury (GEM) has been measured from Can Thanh High School (CTHS), a suburban coastal site in southern Vietnam to study its characterization and discover the evidence of Hg trans-boundary transport from regional sources (e.g., East Asia). Data collected in July, August, and October 2022 were used in this study, and the overall GEM concentration was 1.61 ± 0.32 ng m-3. The GEM levels were higher in October than in July and August, potentially due to the discrepancy in air mass transport patterns induced by tropical monsoon and source origins of Hg. MERRA-2, backward trajectories, and CALIPSO images revealed the trans-boundary air pollution from continental East Asia to southern Vietnam, evidenced by significantly elevated (> 30%) atmospheric Hg concentrations as well as other air pollutants when the plume arrived at CTHS. Furthermore, our results also imply that atmospheric Hg exported from East Asia could influence large areas in SEA, suggesting the need for more studies in various SEA countries in the upcoming future. This study illustrated the influence of regional Hg emissions on local atmospheric Hg pollution and provided data to improve knowledge of the Hg biogeochemical cycle in SEA.

HONO chemistry at a suburban site during the EXPLORE-YRD campaign in 2018: formation mechanisms and impacts on O3 production

Abstract. HONO is an important precursor for OH radicals that impact secondary-pollutant production. However, there are still large uncertainties about different HONO sources which hinder accurate predictions of HONO concentration and hence atmospheric oxidation capacity. Here HONO was measured during the EXPLORE-YRD campaign (EXPeriment on the eLucidation of the atmospheric Oxidation capacity and aerosol foRmation and their Effects in the Yangtze River Delta), along with other important parameters, enabling us to comprehensively investigate HONO variation characteristics and evaluate the relative importance of different HONO sources by using a box model. HONO showed significant variations, ranging from several tens of parts per thousand to 4.4 ppb. The average diurnal pattern of HONO / NOx showed a maximum of 0.17 around noon and resembled that of j(O1D), indicating the existence of photo-induced sources. Modeling simulations with only the default HONO source (OH + NO) largely underestimated HONO concentrations, with the modeled-averaged noontime HONO concentration an order of magnitude lower than the observed concentration. The calculated strength of the unknown HONO source (Punknown) showed a nearly symmetrical diurnal profile with a maximum of 2.5 ppb h−1 around noon. The correlation analysis and sensitivity tests showed that the photo-induced NO2 conversion on the ground was able to explain Punknown. Additional HONO sources incorporated into the box model improved the model's performance in simulating HONO concentrations. The revised box model reproduced the nighttime HONO concentration well but still underestimated the daytime HONO concentration. Further sensitivity tests indicated the underestimation of daytime HONO was not due to uncertainties of photo-induced NO2 uptake coefficients on the ground or aerosol surfaces or the enhancement factor of nitrate photolysis but was more likely due to other sources that were not considered in the model. Among the incorporated HONO sources and the default gas-phase source, photo-induced NO2 conversion on the ground dominated the modeled HONO production during the daytime, accounting for 71 % of the total, followed by NO + OH, NO2 hydrolysis on the ground surface, vehicle emissions, photo-induced NO2 conversion on the aerosol surface, nitrate photolysis and NO2 hydrolysis on the aerosol surface. NO2 hydrolysis on the ground surface was the major source of nighttime HONO, contributing 55 % of total HONO production. HONO photolysis contributed 43 % of ROx production during the daytime, followed by O3 photolysis (17 %), HCHO photolysis (14 %), ozonolysis of alkenes (12 %) and carbonyl photolysis (10 %). With observed HONO as a model constraint, the average peak of net ozone production rate increased by 88 % to 12.6 ppb h−1 compared to that without observed HONO as a model constraint, indicating HONO evidently enhanced O3 production and hence aggravated O3 pollution in summer seasons. Our study emphasized the importance of heterogeneous NO2 conversion on the ground surface in HONO production and accurate parameterization of HONO sources in predicting secondary-pollutant production.

A three-channel thermal dissociation cavity ring-down spectrometer for simultaneous measurement of ambient total peroxy nitrates, total alkyl nitrates, and NO2

A newly constructed thermal dissociation cavity ring-down spectrometer (TD-CRDS) for the simultaneous measurement of ambient total peroxy nitrates (ΣPNs, RO2NO2), total alkyl nitrates (ΣANs, RONO2), and NO2 was presented in this work. ΣPNs and ΣANs were detected as NO2 with the CRDS instrument after thermal dissociation. PNs and ANs completely dissociated at 180 °C and 360 °C, with conversion efficiencies of 96 % and 99 %, respectively. The effects of NO2 and NO on measurement in different temperatures and two types of thermal dissociation inlet (TDI) were further explored. The influence of ambient NO2 and NO on PNs and ANs in the improved TDI (TDI-2) was significantly improved. To further enhance the measurement accuracy, the consistency of the observed NO2 in the three channels was tested, which achieved good agreement. The detection limits of the TD-CRDS instrument for NO2, ΣPNs, and ΣANs were determined as 6.5, 6.8, and 8.6 pptv (10 s, 1σ), respectively. Observations of PNs and ANs were conducted in a suburban site in Hefei, China, from September 2–30, 2021, using the TD-CRDS instrument, and the consecutive time series of PNs and ANs were derived, verifying the capability of the TD-CRDS instrument for continuous field observations of ΣPNs and ΣANs.

Characterising temporal variability of PM2.5/PM10 ratio and its correlation with meteorological variables at a sub-urban site in the Taj City

The problem of air pollution poses a major challenge in the city of Taj, Agra because of rapid urbanization and tourism. Research on PM2.5/PM10 ratio contributes to a deeper understanding of the air pollution scenario and promoting sustainable development. This study was carried out at a suburban site in Agra (Jan 2021-Dec, 2022). We analyzed PM2.5/PM10 ratios, and their correlation with Air Quality Index and meteorological factors using various statistical approaches in the OpenAir package in RStudio. The mean concentrations of PM2.5 and PM10 were 46 and 67 μg/m3, respectively. The PM2.5/PM10 ratio was 0.65, indicating fine particulate dominance. Diurnal, intra-annual, and weekly cycles of PM2.5, PM10, and PM2.5/PM10 ratios were examined. PM2.5/PM10 ratio increased with increasing AQI. Correlation analysis revealed, a strong positive correlation (r = 0.94) between PM10 and PM2.5 while the PM2.5/PM10 ratios showed negative association with wind speed (WS), and temperature, and positive association with relative humidity (RH). Higher RH led to higher PM2.5/PM10 ratios indicating worsening of PM2.5 pollution during winter and post-monsoon. Bivariate polar plots exhibited the lowest PM2.5/PM10 ratios in summer at high WS (>10 m/s) from the west, and the highest PM2.5/PM10 ratios in winter and post-monsoon at low WS (<10 m/s).

Mercury content and elemental composition of fruticose lichens from Nahuel Huapi National park (Patagonia, Argentina): Time trends in transplanted and in situ grown thalli

Lichens have a unique structure involving the symbiosis of fungus and algae and can grow on almost any type of substrate. They absorb gases, water, nutrients and pollutants through their cortex, and thus are good indicators of environmental processes, enabling the biomonitoring of environmental pollutants. These organisms are widely distributed; however, as certain species do not occur in some areas, transplants are commonly used to monitor air pollution. In this study, transplants of the fruticose species Protousnea magellanica were set up at the EMMA Station (Global Mercury Observation System, GMOS) located at a suburban site of San Carlos de Bariloche city within Nahuel Huapi National Park (North Patagonia, Argentina). The transplants were used to assess the uptake of certain elements, particularly the accumulation of mercury. Periodic samplings of the transplanted species P. magellanica and the naturally occurring Usnea pusilla were performed concurrently at the experimental site over 483 days of experimental exposure. The elemental composition and concentration of the thalli of these species were determined by Neutron Activation Analysis in a nuclear reactor. Atmospheric mercury concentration (Gaseous Elemental Mercury, GEM) was monitored at the EMMA Station by an automated cold vapor atomic fluorescence system (Tekran 2537B). Mercury concentrations in the lichens were at least three orders of magnitude higher than atmospheric mercury levels (0.80–0.94 ng/m3, ppt), highlighting the accumulation capacity of these organisms. Concentrations found in P. magellanica thalli (0.080–0.327 μg/g dry weight, ppm) lay within the range of values reported previously in lichens from the Nahuel Huapi National Park with low anthropogenic impact. During experimental exposure both lichen species displayed the same trend in Hg content. Total Hg increased from T0 to T1 (day 25) and then decreased up to approximately T4 (day 385). In U. pusilla, the positive relationship between Hg content and lithophilic elements such as La, suggested preferential Hg uptake from airborne particles (deposited dust).

TROPOMI NO2 Sentinel-5P data in the Community of Madrid: A detailed consistency analysis with in situ surface observations

Excess reactive nitrogen emissions from anthropogenic activities can negatively impact the natural environment. The sensor TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5 Precursor (Sentinel-5P) satellite is capable of providing data on tropospheric NO2 vertical column densities (VCDs). This work investigates NO2 data retrieved from TROPOMI to study the spatial and temporal patterns of NO2 pollution compared with surface-level concentration measurements in the Community of Madrid in 2022. A high linear correlation coefficient (r) was obtained by comparing daily Level-3 tropospheric TROPOMI NO2 data with ground-based data from air quality monitoring stations at satellite overpass time (r = 0.78). Since the overpasses of Sentinel-5P over the region consistently occur between 12:00 and 4:00 p.m. local time, a second correlation analysis was carried out by averaging all available data from both sources within that interval, resulting in an even higher coefficient (r = 0.81). Results showed a lower correlation at rural sites compared to urban and suburban sites. Examining the monthly and weekly variations of NO2 concentration from satellite data and in situ measurements, similar tendencies in NO2 concentration were observed from both sources. In agreement with previous studies, the cold months and weekdays exhibited higher NO2 concentrations. It was concluded that TROPOMI NO2 data and in situ measurements yield a strong correlation for the Community of Madrid target area, and TROPOMI data can be further investigated to propose pollution mitigation policies.

Monitoring gaseous pollutants using passive sampling in the Philadelphia region

ABSTRACT Air pollution can have deleterious impacts on human health and the environment. Historically, air pollution studies have focused more on cities. However, it is also important to consider the impact on large suburban populations living closer to the major cities. In this study, nitrogen oxides (nitrogen dioxide and nitric oxide), sulfur dioxide, ozone, and ammonia concentrations were measured from fifteen sites in the Greater Philadelphia area, Pennsylvania, USA using Ogawa passive samplers from September 2021 to May 2022. The fall season had the highest mean NOx concentrations (11.03 ± 4.51 ppb), and spring had the highest mean O3 concentration (18.65 ± 6.71 ppb) compared to other seasons. NOx concentrations were higher at suburban (30.43 ± 33.79 ppb) and urban sites (22.49 ± 12.54 ppb) compared to semi-rural sites (11.08 ± 9.20 ppb). SO2 was not detected in most of the measurements. The positive statistically significant correlation between NO and NH3 in urban (R2 = 0.33, p-value <0.05) and suburban sites (R2 = 0.37, p-value <0.05) during winter and spring, respectively, suggests a high attribution of traffic emissions to NH3 at urban and suburban sites. Influence of traffic emissions on air pollutant values for the study region is also supported by similar NOx concentrations between suburban and urban sites as well as decreasing NO2/NOx ratios with increased distance from expressways. This study shows that passive sampling can be effectively used for assessing spatial and seasonal variations in air pollutants within an area of diverse land use. Implications: This study presents the findings of temporal and seasonal patterns for nitrogen dioxide, nitric oxide, tropospheric ozone, and ammonia at urban, suburban, and semi-rural areas of the greater Philadelphia region. The main objective of the study is to monitor air pollution in suburban and semi-rural areas which are not monitored for air pollution. We monitored from a total of fifteen sites in three seasons to assess air pollution in suburban and semi-rural areas near the major city in the United States – Philadelphia. The findings are important to learn how air quality is affected in suburban and semi-rural areas near the major city. The study also shows the useful application of inexpensive passive sampling technique for measuring air pollution.

OPTIMAL LONG-RANGE-WIDE-AREA-NETWORK PARAMETERS CONFIGURATION FOR INTERNET OF VEHICLES APPLICATIONS IN SUBURBAN ENVIRONMENTS

In this paper, the effect of Long-Range wireless technology parameters on signal propagation in suburban environments is investigated. Wireless propagation modeling provides information about the wireless channel and its impact on communication links. Received signal strength and coverage area are evaluated to determine signal path loss. The operating frequency of 433 MHz Long Range Wireless Area Network is utilized with different spreading factors, bandwidths, and code rates. Empirical propagation models are utilized to predict a mathematical model based on measured empirical signal strength in a suburban site in Baghdad City. The measured signal strength and signal-to-noise ratio values were obtained through drive tests in an Internet of Vehicles environment to design a network that could accurately report vehicle locations. The LoRa parameters affected the calculated path loss exponent, leading to various predictions in the network design. The path loss exponent exhibited instability due to the presence of obstacles and different long-range parameter settings. Path loss exponent deviation fluctuates due to bandwidth and spreading factor variations. Path loss exponent reduced at higher coding rates for more protection purposes. Packet ratio reception improved as the coding rate increased. To minimize the impact of the path loss on network design, an optimization policy was employed to determine the best parameters that resulted in the lowest path loss. The optimal path loss obtained at LoRa configuration parameters settings with spreading factor (7), bandwidth (500 kHz), and code rate (4/5).

Chemical Composition and Source of PM2.5 during Winter Heating Period in Guanzhong Basin

An intensive field campaign was carried out from December 2022 to March 2023 at six different sites across five major cities (Xi’an, Baoji, Xianyang, Weinan, and Hancheng) in the Guanzhong Basin, China, covering most of the heating period there, which is characterized by high PM2.5 pollution levels. During the campaign, the mean PM2.5 concentrations at these sites exceeded the 24 h PM2.5 standard (75 μg m−3), except the site at Hancheng, with mean PM2.5 concentrations of 57.8 ± 32.3 μg m−3. The source apportionment of PM2.5 varied significantly across sites, with vehicle exhaust being the dominant source at urban sites located in Xi’an and Baoji, coal combustion at suburban sites in Hancheng, and comparable contribution from coal combustion and industrial emissions at suburban sites in Xianyang and Weinan. Compared with clean condition, the contribution of vehicle exhaust and secondary inorganic sources (SIs) were largely enhanced during heavy PM2.5 pollution periods, while the contribution from biomass burning (BB) and dust decreased significantly at all sites. Combined with an analysis of meteorological parameters, the study further found that higher contributions of SIs and heavy PM2.5 pollution were generally associated with higher relative humidity (RH). In addition, higher PM2.5 concentrations at suburban sites were related to lower wind speeds, which could be explained by the stagnant condition favoring the accumulation of local emissions as well as the formation of secondary pollutants. In contrast, at urban sites (e.g., Xianyang), higher PM2.5 concentrations were more associated with the strong influence of vehicle exhaust at slightly higher wind speeds.

Evaluation of 30 urban land surface models in the Urban‐PLUMBER project: Phase 1 results

AbstractAccurately predicting weather and climate in cities is critical for safeguarding human health and strengthening urban resilience. Multimodel evaluations can lead to model improvements; however, there have been no major intercomparisons of urban‐focussed land surface models in over a decade. Here, in Phase 1 of the Urban‐PLUMBER project, we evaluate the ability of 30 land surface models to simulate surface energy fluxes critical to atmospheric meteorological and air quality simulations. We establish minimum and upper performance expectations for participating models using simple information‐limited models as benchmarks. Compared with the last major model intercomparison at the same site, we find broad improvement in the current cohort's predictions of short‐wave radiation, sensible and latent heat fluxes, but little or no improvement in long‐wave radiation and momentum fluxes. Models with a simple urban representation (e.g., ‘slab’ schemes) generally perform well, particularly when combined with sophisticated hydrological/vegetation models. Some mid‐complexity models (e.g., ‘canyon’ schemes) also perform well, indicating efforts to integrate vegetation and hydrology processes have paid dividends. The most complex models that resolve three‐dimensional interactions between buildings in general did not perform as well as other categories. However, these models also tended to have the simplest representations of hydrology and vegetation. Models without any urban representation (i.e., vegetation‐only land surface models) performed poorly for latent heat fluxes, and reasonably for other energy fluxes at this suburban site. Our analysis identified widespread human errors in initial submissions that substantially affected model performances. Although significant efforts are applied to correct these errors, we conclude that human factors are likely to influence results in this (or any) model intercomparison, particularly where participating scientists have varying experience and first languages. These initial results are for one suburban site, and future phases of Urban‐PLUMBER will evaluate models across 20 sites in different urban and regional climate zones.

Spatial and diurnal variations of aerosol organosulfates in summertime Shanghai, China: potential influence of photochemical processes and anthropogenic sulfate pollution

Abstract. Organosulfates (OSs) are ubiquitous aerosol components, which has seen intense research over years. However, spatial and diurnal variations in OS formation in polluted atmospheres remain poorly understood. In this study, 130 OS species were quantified (or semi-quantified) in ambient fine particulate matter (PM2.5) collected in urban and suburban Shanghai (East China) in the summer of 2021. Isoprene- and monoterpene-derived OSs were dominant OS groups (averaging 51 % and 19 % of total quantified OSs, respectively), likely indicating a large biogenic contribution to OS formation in summer. Most OSs peaked during daytime, while monoterpene-derived nitrooxy-OSs (NOSm) increased during nighttime. Accordingly, OSs were largely produced via daytime formation processes, rather than nighttime chemistry, except for NOSm. Additionally, although OS formation in the urban and suburban areas exhibited similar diurnal variations, the average concentrations of biogenic and anthropogenic OSs decreased significantly from the urban site to the suburban site. Furthermore, we concretized daytime OS formation based on the interactions among OSs, ultraviolet (UV), ozone (O3), and sulfate (SO42-). Indeed, the concentrations of most OSs were significantly correlated with the values of UV[O3][SO42-] during daytime in both urban and suburban Shanghai. In particular, the correlation between major OSs and UV[O3][SO42-] was stronger than the correlation of major OSs with O3 and SO42-; moreover, there was no significant correlation between major OSs and UV. Thus, higher urban OS events were attributed to the enhanced photochemical processes and sulfate level in the urban area. Overall, this study provides field evidence for the influence of photochemical processes and anthropogenic sulfate on OS formation and has important implications for the mitigation of organic particulate pollution.

Urban and suburban's airborne magnetic particles accumulated on Tillandsia capillaris

Air particle pollution is a current issue that can cause adverse problems to human health and the urban environment. A fraction of these emitted particles is magnetite and iron-rich materials, which may be accumulated by biological indicators and effectively characterized by environmental magnetism methods. Thus, we studied this emitted particle fraction using the epiphytic species Tillandsia capillaris growing in northwestern Argentina's urban, suburban, and rural areas. The accumulated airborne magnetic particles' properties revealed valuable information regarding potentially toxic elements, magnetic mineralogy, sizes, morphology, and concentration. Magnetite was detected in samples from all studied areas, and its remanent coercivity values (Hcr = 32.1–42.6 mT) in (sub)urban sites are similar to other reported cities in Latin America. The concentration of these airborne magnetic particles AMP varied between urban sites (mean and (s.d.) values of in situ magnetic susceptibility κis = 16.2 (9.4) × 10−6 SI, and specific magnetic susceptibility χ = 61.9 (31.4) × 10−8 m3 kg−1) and suburban sites (κis = 13.9 (9.9) × 10−6 SI, and χ = 43.9 (32.2) × 10−8 m3 kg−1), and it was distinctively higher than in clean sites. The spatial distribution of AMP was analyzed using a geostatistical model for the concentration-dependent magnetic parameter κis, which showed zones with high magnetic particle accumulation associated with vehicular traffic in the city and industrial emission in a suburban site. Among concentration-dependent magnetic parameters, the κis is recommended for magnetic biomonitoring because Tillandsia species' individuals are not processed for laboratory measurements, preserving them and allowing us the possibility of measurements over time.

Impact of COVID-19 pandemic lockdown on atmospheric concentrations of particulate matter, trace gases and volatile organic compounds at a suburban site of Agra

Impact of COVID-19 pandemic lockdown on atmospheric concentrations of particulate matter, trace gases and volatile organic compounds at a suburban site of Agra

Optimizing Telehealth Services: A Mixed-Methods Needs Assessment Conducted Among Community Health Center Patients.

The COVID-19 pandemic increased telehealth services in federally funded community health centers (CHCs). Yet little is known about common determinants of use among CHC patients. We examined the use of telehealth among patient participants at 1 large CHC network providing care to underserved populations at urban and suburban sites in the Midwest. We conducted a mixed-methods study utilizing a sequential explanatory design. Participants were English and/or Spanish-speaking adults who attended ≥1 visits for themselves or their child over a 12-month period at any practice location. Research staff conducted a structured phone survey of eligible adults. The results subsequently facilitated purposive sampling of telehealth "users" and "nonusers" for qualitative phone interviews. The survey participants included 500 adults. Most had access to the resources needed to utilize telehealth, including a smartphone (90.4%) and home internet (83.0%). About half (50.8%) "rarely or never" had problems with internet speed, reliability, or quality. Most (81.1%) were aware of the patient portal and 59.8% had utilized video visits. Participants who were Spanish-speaking and with limited English proficiency faced some of the greatest barriers. Qualitative interview participants included 12 users and 12 nonusers of telehealth. Users found telehealth convenient and efficient, while nonusers lacked awareness about how telehealth services could be beneficial or needed assistance to sign up, join, or use telehealth. Most participants had the resources and awareness necessary to use telehealth services. Those who use them appreciate the convenience and efficiency. Nevertheless, additional support may be needed to prevent telehealth from exacerbating health inequities.

Spatiotemporal organization of cryptic North American Culex species along an urbanization gradient.

Landscape heterogeneity creates diverse habitat and resources for mosquito vectors of disease. A consequence may be varied distribution and abundance of vector species over space and time dependent on niche requirements.We tested the hypothesis that landscape heterogeneity driven by urbanization influences the distribution and relative abundance of Culex pipiens, Cx. restuans, and Cx. quinquefasciatus, three vectors of West Nile virus (WNv) in the eastern North American landscape. We collected 9,803 cryptic Culex from urban, suburban, and rural sites in metropolitan Washington, District of Columbia, during the months of June-October, 2019-2021. In 2021, we also collected mosquitoes in April and May to measure early-season abundance and distribution. Molecular techniques were used to identify a subset of collected Culex to species (n = 2,461). Ecological correlates of the spatiotemporal distribution of these cryptic Culex were examined using constrained and unconstrained ordination.Seasonality was not associated with Culex community composition in June-October over three years but introducing April and May data revealed seasonal shifts in community composition in the final year of our study. Culex pipiens were dominant across site types, while Cx. quinquefasciatus were associated with urban environments, and Cx. restuans were associated with rural and suburban sites. All three species rarely coexisted.Our work demonstrates that human-mediated land-use changes influence the distribution and relative abundance of Culex vectors of WNv, even on fine geospatial scales. Site classification, percent impervious surface, distance to city center, and longitude predicted Culex community composition. We documented active Culex months before vector surveillance typically commences in this region, with Culex restuans being most abundant during April and May. Active suppression of Cx. restuans in April and May could reduce early enzootic transmission, delay the seasonal spread of WNv, and thereby reduce overall WNv burden. By June, the highest risk of epizootic spillover of WNv to human hosts may be in suburban areas with high human population density and mixed Culex assemblages that can transmit WNv between birds and humans. Focusing management efforts there may further reduce human disease burden.

Soils are a non-negligible source of NO in a UK suburban greenspace and SE Australian Eucalyptus forest

Nitrogen oxides, particularly NO and NO2 (NOx), are primary air pollutants that also play an essential role in the atmospheric oxidation of volatile organic compounds, resulting in ozone and secondary organic aerosol formation. It is therefore critical to fully characterise NOx sources and sinks to understand tropospheric photochemistry and hence local- to regional-scale air quality. Human activities such as transport and power plants are well-known NOx emission sources in urban areas, whereas natural sources such as soils have been considered to contribute more substantially in rural and remote areas. However, soil NO emissions are poorly characterised and therefore underrepresented in models. To improve our understanding of soil as a source of NO, we measured diurnal patterns in soil NO concentrations at a suburban site in the UK and a remote field site in Australia to determine whether soils contribute to local atmospheric NO, and to identify the potential drivers of soil NO emissions. Mean soil NO concentrations in both UK campaigns 1.76 ± 0.92 ppb in summer and 0.91 ± 0.37 ppb in winter) were higher than those measured in Australia (0.73 ± 0.73 ppb). The diel patterns of NO concentrations (both sites) and emissions rates (Australia) showed a clear peak corresponding to local emission sources, but variation in NO was also related to either vapour pressure deficit (R2 = 0.88 in UK summer, R2 = 0.51 in Australia, both p < 0.05) or solar radiation (R2 = 0.06 with p > 0.4 in UK summer, R2 = 0.71 with p < 0.05 in Australia) during the daylight hours, indicating biogenic origin of soil NO. Our work demonstrates that biogenic soil emissions of NO are non-negligible, estimated at around 1.32 % of total NO emissions at the remote site, and 0.22 % at the urban site, and must be accounted for in global and regional atmospheric chemistry-climate modelling and NOx reduction strategies.

Improving Pediatric Procedural Skills for EMS Clinicians: A Longitudinal Simulation-Based Curriculum with Novel, Remote, First-Person-View Video-Based Outcome Measurement

Objective Emergency medical services (EMS) clinicians are expected to provide expert care to all patients, but face obstacles in maintaining skillsets required in the care of critically ill or injured children. The objectives of this study were to describe and assess the effectiveness of a pediatric-focused, simulation-based, procedural training program for EMS clinicians, delivered on-site by a pediatric simulation education team. We also describe a novel, remote, asynchronous performance outcome measurement system using first-person-view video review. Methods This was a prospective study of simulation-based training and procedural outcomes. The study population involved EMS clinicians at three fire-based EMS agencies stratified as urban, suburban, and rural sites. The primary outcome was performance of intraosseous catheterization (IO), bag-valve-mask ventilation (BVM), and supraglottic device placement (SGD), measured across three time points. Secondary outcomes were identification of differences across EMS agencies and participant survey responses. Results We obtained video data from 122 clinicians, totaling 561 videos, with survey response rates of 89.0–91.3%. Pre-intervention scores were high: least-square means (95% confident-intervals) 9.5 (8.9, 10.2) for IO; 9.6 (9.3, 9.9) for BVM; and 11.6 (10.9, 12.2) for SGD. There was significant improvement post-intervention: 11.5 (10.7, 12.3) for IO; 11.0 (10.7, 11.4) for BVM; and 13.6 (12.8, 14.4) for SGD. Improvement was maintained at follow-up after a median of 9.5 months: 10.5 (9.8, 11.2) for IO; 10.2 (9.9, 10.6) for BVM; and 12.4 (11.7, 13.1) for SGD. There were no statistical differences between sites. Of survey respondents, half had not cared for a critically ill or injured child in at least a year, the vast majority had not had hands-on pediatric training in over 6 months, and the majority felt that training should occur at least every 6 months. Conclusions Our pediatric-focused, simulation-based procedural training program was associated with improvement and maintenance of high-baseline procedural performance for EMS clinicians over the study period. Findings were consistent across sites. Remote assessment was feasible. Participant surveys emphasized a desire for more pediatric-focused training and highlighted the low frequency of clinical exposure to procedures potentially needed in the care of critically ill or injured pediatric patients.