Risk factors of sleep-disordered breathing and poor asthma control in children with asthma.

BACKGROUND: Sleep-disordered breathing (SDB) may lead to poor asthma control in children. OBJECTIVE: To identify risk factors of SDB in children with asthma and assess its impact on asthma control. METHODS: In this cross-sectional study, we collected data of outpatients with asthma at the Children's Hospital of Chongqing Medical University from June 2020 to August 2021. The Pediatric Sleep Questionnaire-Sleep-Related Breathing Disorder and the age-appropriate asthma control tests Childhood Asthma Control Test and Test for Respiratory and Asthma Control in Kids were completed. RESULTS: We enrolled 397 children with a male-to-female ratio of 1.7:1 and a mean age of 5.70 ± 2.53 years. The prevalence of SDB was 21.6%. Allergic rhinitis (odds ratio OR = 3.316), chronic tonsillitis (OR = 2.246), gastroesophageal reflux (OR = 7.518), adenoid hypertrophy (OR = 3.479), recurrent respiratory infections (OR = 2.195), and a family history of snoring (OR = 2.048) were risk factors for the development of combined SDB in children with asthma (p < 0.05). Asthma was poorly controlled in 19.6% of the children. SDB (OR = 2.391) and irregular medication use (OR = 2.571) were risk factors for poor asthma control (p < 0.05). CONCLUSIONS: Allergic rhinitis, chronic tonsillitis, gastroesophageal reflux, adenoid hypertrophy, recurrent respiratory infections, and a family history of snoring were independent risk factors for the development of SDB in children with asthma. SDB and irregular medication use were independent risk factors for poor asthma control.

The role of satellite remote sensing in mitigating and adapting to global climate change.

Climate change has critical adverse impacts on human society and poses severe challenges to global sustainable development. Information on essential climate variables (ECVs) that reflects the substantial changes that have occurred on Earth is critical for assessing the influence of climate change. Satellite remote sensing (SRS) technology has led to a new era of observations and provides multiscale information on ECVs that is independent of in situ measurements and model simulations. This enhances our understanding of climate change from space and supports policy-making in combating climate change. However, it remains challenging to remotely retrieve ECVs due to the complexity of the climate system. We provide an update on the studies on the role of SRS in climate change research, specifically in monitoring and quantifying ECVs in the atmosphere (greenhouse gases, clouds and aerosols), ocean (sea surface temperature, sea ice melt and sea level rise, ocean currents and mesoscale eddies, phytoplankton and ocean productivity), and terrestrial ecosystems (land use and land cover change and carbon flux, water resource and hydrological hazards, solar-induced chlorophyll fluorescence and terrestrial gross primary production). The benefits and challenges of applying SRS in climate change studies are also examined and discussed. This work will help us apply SRS and recommend future SRS studies to mitigate and adapt to global climate change.

Risk tradeoffs between nitrogen dioxide and ozone pollution during the COVID-19 lockdowns in the Greater Bay area of China.

Photochemical regime for ozone (O3) formation is complicated in the sense that reducing emission of nitrogen oxides (NOx) may increase O3 concentration. The lockdown due to COVID-19 pandemic affords a unique opportunity to use real observations to explore the O3 formation regime and the effectiveness of NOx emission control strategies. In this study, observations from ground networks during the lockdowns were used to assess spatial disparity of the Ratio of Ozone Formation (ROF) for nitrogen dioxide (NO2) reduction in the Greater Bay Area (GBA) of China. The health risk model from Air Quality Health Index (AQHI) system in Hong Kong was adopted to evaluate the risk tradeoffs between NO2 and O3. Results show that the levels of O3 increase and NO2 reduction were comparable due to high ROF values in urban areas of central GBA. The ozone reactivity to NO2 reduction gradually declined outwards from central GBA. Despite the O3 increases, the NOx emission controls reduced the Integrated Health Risk (IHR) of NO2 and O3 in most regions of the GBA. When risk coefficients from the AQHI in Canada or the global review were adopted in the risk analyses, the results are extremely encouraging because the controls of NOx emission reduced the IHR of NO2 and O3 almost everywhere in the GBA. Our results underscore the importance of using a risk-based method to assess the effectiveness of emission control measures and the overall health benefit from NOx emission controls in the GBA.

Retrieval of total and fine mode aerosol optical depth by an improved MODIS Dark Target algorithm.

Total and fine mode aerosol optical depth (AODT and AODF), as well as the fine mode fraction (FMF = AODF/AODT), are critical variables for climate change and atmospheric environment studies. The retrievals with high accuracy from satellite observations, particularly FMF and AODF over land, remain challenging. This study aims to improve the Moderate-resolution Imaging Spectro-radiometer (MODIS) land dark target (DT) algorithm for retrieving AODT, AODF, and FMF on a global scale. Based on the fact that the underestimated surface reflectance (SR) could overestimate the AODT and underestimate the aerosol size parameter in the DT algorithm, two robust schemes were developed to improve SR determination: the first (NEW1 DT) used the top of the atmosphere reflectance instead of SR at 2.12 µm; the second (NEW2 DT) used eleven-year MODIS data to establish a monthly spectral SR relationship model (2.12-0.47 and 2.12-0.65 µm) database at pixel-by-pixel scale. Then a novel lookup table approach based on the physical process was proposed to retrieve the AODF and FMF. The new MODIS AODT, FMF, and AODF were compared to AERosol RObotic NETwork (AERONET) retrievals. Results showed that the root mean square error (RMSE) was 0.096-0.103, 0.098-0.099, and 0.167-0.180 for the new AODTs, AODFs, and FMFs, respectively, which were better than that of the Collection 6.1 (C6.1) DT (0.117, 0.235, and 0.426) in the validation by global AERONET sites. From the validation results, NEW2 DT provided better AODT and coarse mode AOD retrievals, while NEW1 DT had better AODF and FMF performances. The spatial patterns of AODF, FMF, and AODC of the new DT algorithms were comparable to those of the Polarization and Directionality of the Earth's Reflectances aerosol product. Hence, the new algorithms have the potential to provide global AODT, FMF, and AODF products over land to the scientific community with high accuracy using long-term MODIS data.

Spatial-temporal distribution and evolutionary characteristics of water environment sudden pollution incidents in China from 2006 to 2018.

Sudden water pollution incidents (SWPI) are random and harmful, which is a problem that cannot be ignored in ecological environment governance and economic development. Identifying spatial-temporal distribution characteristics of SWPI is essential for the disaster prevention and the early warning of water environment. The Kernel Density (DE) and spatial mean center of SWPI transfer curve were used to explore the characteristics with the dataset of 1174 cases from 2006 to 2018 in China. Results showed that: (1) From the time point of view, there was an overall upward trend in the overall number of SWPI. (2) At a regional scale, Eastern China, Southwest China, and Southern China underwent a high frequency with 69.93% of SWPI. The Fujian, Guangdong and Chongqing provinces were specified as the top 3 provinces with incident frequencies. The Yangtze River Basin and the Pearl River Basin were two regions where water pollution incidents occur more often, more than 50% of incidents among basins in China every year. (3) In general, SWPI presents a northeast-southwest distribution pattern and center of SWPI moves in the direction of west by south. (4) More than half of the incidents (57.24% of the total) were induced by illegal pollutant discharge and production safety accidents.

Exploring the variation of black and brown carbon during COVID-19 lockdown in megacity Wuhan and its surrounding cities, China.

Absorbing carbonaceous aerosols, i.e. black and brown carbon (BC and BrC), affected heavily on climate change, regional air quality and human health. The nationwide lockdown measures in 2020 were performed to against the COVID-19 outbreak, which could provide an important opportunity to understand their variations on light absorption, concentrations, sources and formation mechanism of carbonaceous aerosols. The BC concentration in Wuhan megacity (WH) was 1.9 µg m-3 during lockdown, which was 24% lower than those in the medium-sized cities and 26% higher than those in small city; in addition, 39% and 16-23% reductions occurred compared with the same periods in 2019 in WH and other cities, respectively. Fossil fuels from vehicles and industries were the major contributors to BC; and compared with other periods, minimum contribution (64-86%) mainly from fossil fuel to BC occurred during the lockdown in all cities. Secondary BrC (BrCsec) played a major role in the BrC light absorption, accounting for 65-77% in WH during different periods. BrCsec was promoted under high humidity, and decreased through the photobleaching of chromophores under higher Ox. Generally, the lockdown measures reduced the BC concentrations significantly; however, the variation of BrCsec was slight.

Removing the effects of meteorological factors on changes in nitrogen dioxide and ozone concentrations in China from 2013 to 2020.

Previous studies on long-term ozone (O3) variations in China have reported inconsistent conclusions on the role of meteorological factors in controlling said variations. In this study, we used an observation-based decomposition model to conduct an up-to-date investigation of the effects of meteorological factors on the variations in nitrogen dioxide (NO2) and O3 concentrations in China in the summer from 2013 to 2020. The variations in NO2 and O3 concentrations after removing the major meteorological effects were then analyzed to improve our understanding of O3 formation regimes. Ground measurements show that both NO2 and O3 concentrations decreased in eastern, central, and southeastern China (e.g., NO2 and O3 concentrations in Wuhan reduced by 4.3 and 6.2 ppb, respectively), which was not anticipated. Analyses of meteorological effects showed that reduced wind strength, decreased temperature, and increased relative humidity significantly reduced O3 concentrations in eastern and central China (e.g., by 10.5 ppb in Wuhan). After removing the major meteorological effects, the O3 trends were reversed in eastern and central China (e.g., increased by 4.9 ppb in Wuhan). The contrasting trends in NO2 and O3 concentrations suggest that their O3 formations were sensitive to volatile organic compounds (VOC-limited regime). In southeastern China, both NO2 and O3 concentrations decreased, implying that the O3 formation regimes changed to mixed sensitive or nitrogen oxide-limited (NOx-limited) regimes. The meteorological effects varied by region and may play a dominant role in controlling the long-term O3 variation. Our results indicate that the attribution of O3 variation to emission control without accounting for meteorological effects can be misleading.

Assessing the ecological balance between supply and demand of blue-green infrastructure.

Given that improving urban ecological environment requires a clear recognition of the urban ecological elements, investigating the ecosystem service capabilities of urban green-blue infrastructures (UGBIs) becomes ever important. This study aims to reveal and compare the synergistic ecosystem service ability of UGBIs with different characteristics and the relationship with human demand in Wuhan city. It was found that the climate regulation service and water regulation service value of lake-type parks both reached the highest over the other UGBIs. Nature-type parks revealed the most capable cultural service, and green-type parks demonstrated the greatest exercise cultural service value. The analysis showed that the ecosystem services delivered by the UGBIs were influenced by the park area, the total value of the normalized difference vegetation index and normalized water body index, and the distance from the city centre. Furthermore, a significant spatial phenomenon was found that the ecological capacity of lake-type parks in the city centre was higher than that of the other UGBIs at the same location. Regarding the relationship with the human activity intensity, the high-demand and high-supply regions were mainly concentrated in highly developed areas in terms of regulating services. Nevertheless, a severe environmental inequality occurred in small urban centres, which requires urgent attention from the government. This work answered the question of where and how to optimize the green-blue infrastructures in Wuhan, and it contributes to the construction of the existing blue-green space.

Spatial Disparity of Meteorological Impacts on Carbon Monoxide Pollution in China during the COVID-19 Lockdown Period.

Lockdown due to the novel coronavirus disease 2019 (COVID-19) pandemic offers a unique opportunity to study the factors governing the variation in air pollution. A number of studies have investigated the cause underlying the occurrence of heavy haze pollution around the world during the lockdown period. However, information about spatiotemporal variations in gaseous pollutants and detailed quantifications of potential meteorological (METRO) impacts are limited. Ground measurements show that carbon monoxide (CO) pollution deteriorated in northern China despite strict control of human and industrial activities during the lockdown period in early 2020. In this study, a four-dimensional decomposition model was used to quantitatively extract the METRO impacts on the CO pollution over China. The results show that weakened winds elevated CO concentrations near Beijing and in northeastern China. Increased temperatures slightly elevated CO concentrations in northern and eastern China but reduced CO concentrations in northwestern China. Remarkable amounts of CO increases in northern China (e.g., by 0.21 mg/m3 within Beijing) were explained by anomalously high humidity, which could be associated with an enhanced interaction between aerosol and the boundary layer. After excluding the METRO impacts, the CO concentrations drastically declined across China (e.g., by 0.22 mg/m3 within Beijing), indicating that the lockdown indeed greatly lessened CO concentrations. However, the adverse METRO conditions counteracted the beneficial outcomes of emission reductions, leading to a deterioration of the CO pollution in northern China. These results indicate that the METRO factors can play a critical role in worsening air pollution despite a strict control of anthropogenic emissions.

[Analysis of Different Particle Sizes, Pollution Characteristics, and Sources of Atmospheric Aerosols During the Spring Dust Period in Beijing].

To understand the evolution of the physical and chemical properties of dust aerosols in the atmosphere, the concentrations and chemical compositions of differently sized particles were continuously observed and analyzed using an ion chromatograph and carbonaceous analyzer during the outbreak of dust in May 2017 in Beijing. The concentrations of total suspended particulate (TSP), water-soluble organic carbon (WSOC), elemental carbon (EC), OC, and water-soluble inorganic ions were (2237.59±681.49), (29.90±18.05), (1.46±3.05), (67.35±29.07), and (136.75±46.38) µg·m-3 during the dust period, respectively, and significantly exceeded that of the non-dust period, except for EC. The Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO3-, SO42-, and WSOC concentrations during the dust storm period were 11.55, 3.00, 14.88, 14.89, 9.40, 4.60, 2.40, 3.91, and 1.83 times higher than that during the non-dust period. The growth of crustal ions, such as Ca2+ and K+, was notably the largest and NH4+ and NO3- were minimal. The size distribution indicates that crustal ions primarily occur in the coarse mode during the whole sampling campaign. The SO42- and NO3- ions are slightly bimodal during the dust storm, with a dominant peak in the coarse mode at 4.7-5.8 µm and a very minor peak in the fine mode with a size range of 0.43-0.65 µm. During the non-dust period, SO42- is the dominant mode in the fine mode, while NO3- changes little compared with that during the dust period, which indicates that heterogeneous reaction with crustal ions is the main formation mechanism of NO3- in the coarse mode. A significant positive correlation was observed between SO42- and the sum of crustal ions during the dust period, indicating that the source of SO42- during the dust period is remote transmission of the dust storm. During the non-dust period, the positive correlation of SO42- with NH4+ indicates that secondary formation is the main source of SO42-. Based on correlation analysis of NO3- with crustal ions and NH4+, both remote transmission and secondary formation are the sources of NO3- during the dust storm and heterogeneous reactions are predominant during the non-dust period.

[Simulation of Atmospheric Nitrous Oxide Profiles Retrieval from AIRS Observations].

Nitrous Oxide is a very important greenhouse gases and ozone-depleting substances. Due to the limited observations, there are still many uncertainties to quantitatively describe the role of nitrous oxide played in both cases. We can retrieve the methane and carbon dioxide gas using thermal infrared satellite data AIRS, but it is rarely for the nitrous oxide retrieval. Therefore, this paper retrieves nitrous oxide profiles from the AIRS data with an Optimal Estimate Method for the first time in China. The issue of the a priori and channels election is discussed. Comparison of the retrieved AIRS profiles with HIPPO profiles show the retrieved profiles are in good agreement with the smoothed HIPPO profiles, and a notable improvement in this algorithm than the eigen vector regression algorithm. For pressures between 300 and 900 hPa, we got the most accurate profiles and the relative error is only 0.1%, which is consistent with the jacobian peaks of the selected channels.

[Analysis of the Influence of Temperature on the Retrieval of Ozone Vertical Profiles Using the Thermal Infrared CrIS Sounder].

Ozone is a particularly critical trace gas in the Earth's atmosphere, since this molecule plays a key role in the photochemical reactions and climate change. The TIR measurements can capture the variability of ozone and are weakly sensitive to the lowermost tropospheric ozone content but can provide accurate measurements of tropospheric ozone and higher vertical resolution ozone profiles, with the additional advantage that measurements are also possible during the night. Because of the influence of atmospheric temperature, the ozone profile retrieval accuracy is severely limited. This paper analyze and discuss the ozone absorption spectra and weighting function sensitivity of temperature and its influence on ozone profile retrieval in detail. First, we simulate the change of atmospheric transmittance and radiance by importing 1 K temperature uncertainty, using line-by-line radiative transfer mode under 6 different atmosphere modes. The results show that the transmittance change ratio for 1 K temperature variation was consistent with the transmittance change ratio for 5%-6% change of ozone density variation in all layers of the profile. Then, we calculate the change of weighting function by a temperature error of 1 K, using the Community Radiative Transfer Model (CRTM) for the Cross-track Infrared Sounder (CrIS) on the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite and calculate the corresponding change of retrieval result. The results demonstrate that CrIS is sensitive to Ozone in the middle to upper stratosphere, with the peak vertical sensitivity between 10-100 hPa and the change of weighting function for 1 K temperature variation was consistent with 6% change in the ozone profile. Finally, the paper retrieves ozone profiles from the CrIS radiances with a nonlinear Newton iteration method and use the eigenvector regression algorithm to construct the a priori state. In order to resolve the problem of temperature uncertainty and get high accuracy ozone profile, atmospheric temperature profile and ozone profile are simultaneously retrieved. Comparison of the CrIS retrieved ozone profile with high-vertical-resolution ozonesonde profiles provided by the World Ozone and Ultraviolet Radiation Data Centre (WOUDC) and ERA-Interim ozone profiles indicated that the retrieved ozone profiles are in good agreement with the ozonesonde profiles, and a notable improvement in this algorithm than the retrieval without atmospheric temperature profile, are also better than the ECMWF model profiles. The relative differences are less than 20% for the stratosphere and 50% for the lower troposphere.

[Simulation of atmospheric temperature and moisture profiles retrieval from CrIS observations].

In order to get higher vertical resolution atmosphere profile information, the present paper retrieves atmospheric temperature and moisture profiles from the Cross-track Infrared Sounder (CrIS) on the newly-launched Suomi National Polar-orbiting Partnership (Suomi NPP) and future Joint Polar Satellite System (JPSS) with a nonlinear Newton iteration method by using the profiles retrieved via statical regression method as the first guess, and the issue of channel selection is discussed. The retrieved profiles are compared with radiosonde observations, and National Centers for Environmental Prediction (NCEP) Global Data Assimilation System (GDAS) analyses show that the physical retrievals of temperature and moisture are in good agreement with the distributions from GDAS analysis fields and radiosonde observations, and have a notable improvements of the atmospheric profile retrieval accuracy as compared with the eigenvector regression algorithm. For pressures between 200 and 700 hPa the accuracy is of the order of 1 K for the temperature profile, and 20% for the relative humidity profile is consistent with the jacobian peaks of the selected channels.