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1.
BMJ Open ; 11(2): e043863, 2021 02 17.
Artículo en Inglés | MEDLINE | ID: mdl-33597143

RESUMEN

OBJECTIVES: We aim to assess the impact of temperature and relative humidity on the transmission of COVID-19 across communities after accounting for community-level factors such as demographics, socioeconomic status and human mobility status. DESIGN: A retrospective cross-sectional regression analysis via the Fama-MacBeth procedure is adopted. SETTING: We use the data for COVID-19 daily symptom-onset cases for 100 Chinese cities and COVID-19 daily confirmed cases for 1005 US counties. PARTICIPANTS: A total of 69 498 cases in China and 740 843 cases in the USA are used for calculating the effective reproductive numbers. PRIMARY OUTCOME MEASURES: Regression analysis of the impact of temperature and relative humidity on the effective reproductive number (R value). RESULTS: Statistically significant negative correlations are found between temperature/relative humidity and the effective reproductive number (R value) in both China and the USA. CONCLUSIONS: Higher temperature and higher relative humidity potentially suppress the transmission of COVID-19. Specifically, an increase in temperature by 1°C is associated with a reduction in the R value of COVID-19 by 0.026 (95% CI (-0.0395 to -0.0125)) in China and by 0.020 (95% CI (-0.0311 to -0.0096)) in the USA; an increase in relative humidity by 1% is associated with a reduction in the R value by 0.0076 (95% CI (-0.0108 to -0.0045)) in China and by 0.0080 (95% CI (-0.0150 to -0.0010)) in the USA. Therefore, the potential impact of temperature/relative humidity on the effective reproductive number alone is not strong enough to stop the pandemic.


Asunto(s)
/transmisión , Humedad , Modelos Teóricos , Temperatura , China/epidemiología , Ciudades , Estudios Transversales , Humanos , Estudios Retrospectivos , Estados Unidos/epidemiología
2.
Exp Appl Acarol ; 83(2): 257-270, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33394199

RESUMEN

Female reproductive output and larval survival were determined for American dog ticks, Dermacentor variabilis (Say), from a recently established population near the northern distributional limit in Saskatchewan (Canada). Oviposition took 10-21 days at 25 °C and 95% relative humidity (RH). Temperature and relative humidity had a marked effect on egg development time and larval survival. Unfed larvae survived more than 100 days at 32 °C (with 95% RH) and 25 and 5 °C (with ≥ 85% RH). However, survival times declined markedly at lower relative humidities. In addition, 95% of the larvae placed in field enclosures survived for 140 days over winter during which they were exposed to sub-zero temperatures and 95-100% RH, while covered with snow. The median survival times (LT50) of unfed larvae submerged underwater was 68 days. These results show that D. variabilis larvae in populations near the periphery of the northern distributional limit are adapted to cope with sub-zero temperatures in winter, and can survive in the temporary pools of water created by the spring snow melt.


Asunto(s)
Dermacentor , Rhipicephalus sanguineus , Animales , Canadá , Perros , Femenino , Humedad , Larva , Temperatura
3.
Artículo en Inglés | MEDLINE | ID: mdl-33419216

RESUMEN

Weather and climate play a significant role in infectious disease transmission, through changes to transmission dynamics, host susceptibility and virus survival in the environment. Exploring the association of weather variables and COVID-19 transmission is vital in understanding the potential for seasonality and future outbreaks and developing early warning systems. Previous research examined the effects of weather on COVID-19, but the findings appeared inconsistent. This review aims to summarize the currently available literature on the association between weather and COVID-19 incidence and provide possible suggestions for developing weather-based early warning system for COVID-19 transmission. Studies eligible for inclusion used ecological methods to evaluate associations between weather (i.e., temperature, humidity, wind speed and rainfall) and COVID-19 transmission. The review showed that temperature was reported as significant in the greatest number of studies, with COVID-19 incidence increasing as temperature decreased and the highest incidence reported in the temperature range of 0-17 °C. Humidity was also significantly associated with COVID-19 incidence, though the reported results were mixed, with studies reporting positive and negative correlation. A significant interaction between humidity and temperature was also reported. Wind speed and rainfall results were not consistent across studies. Weather variables including temperature and humidity can contribute to increased transmission of COVID-19, particularly in winter conditions through increased host susceptibility and viability of the virus. While there is less indication of an association with wind speed and rainfall, these may contribute to behavioral changes that decrease exposure and risk of infection. Understanding the implications of associations with weather variables and seasonal variations for monitoring and control of future outbreaks is essential for early warning systems.


Asunto(s)
/transmisión , Tiempo (Meteorología) , Humanos , Humedad , Incidencia , Temperatura
4.
Artículo en Inglés | MEDLINE | ID: mdl-33435301

RESUMEN

The purpose of this study is to investigate whether the relationship between meteorological factors (i.e., daily maximum temperature, minimum temperature, average temperature, temperature range, relative humidity, average wind speed and total precipitation) and COVID-19 transmission is affected by season and geographical location during the period of community-based pandemic prevention and control. COVID-19 infected case records and meteorological data in four cities (Wuhan, Beijing, Urumqi and Dalian) in China were collected. Then, the best-fitting model of COVID-19 infected cases was selected from four statistic models (Gaussian, logistic, lognormal distribution and allometric models), and the relationship between meteorological factors and COVID-19 infected cases was analyzed using multiple stepwise regression and Pearson correlation. The results showed that the lognormal distribution model was well adapted to describing the change of COVID-19 infected cases compared with other models (R2 > 0.78; p-values < 0.001). Under the condition of implementing community-based pandemic prevention and control, relationship between COVID-19 infected cases and meteorological factors differed among the four cities. Temperature and relative humidity were mainly the driving factors on COVID-19 transmission, but their relations obviously varied with season and geographical location. In summer, the increase in relative humidity and the decrease in maximum temperature facilitate COVID-19 transmission in arid inland cities, while at this point the decrease in relative humidity is good for the spread of COVID-19 in coastal cities. For the humid cities, the reduction of relative humidity and the lowest temperature in the winter promote COVID-19 transmission.


Asunto(s)
/epidemiología , Conceptos Meteorológicos , Estaciones del Año , Beijing , China/epidemiología , Ciudades , Humanos , Humedad , Temperatura , Viento
5.
Int J Hyg Environ Health ; 232: 113690, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33434878

RESUMEN

Countries with abundant solar radiation have the potential to invest in simple technologies for deactivation of many bacteria and viruses in medical solid waste. In addition to the traditional Infection and Prevention Control (IPC) measures, these simple technologies contribute to better protection of health care workers in countries with compromised solid management schemes. Monitoring of temperature, relative humidity and ultraviolet inside containers soundly designed to collect disposal infectious waste illustrated to deactivate several viruses and bacteria. Casanova et al., 2010, used some surrogate viruses to overcome the challenges of working with SARS-CoV, concluded that by temperature above 40 °C most of viruses become below levels of detection after 90 min. Here we are proposing a model of a simple transparent container almost 200 L in volume that allow solar energy to be accumulated inside. In summer conditions in the testing site, temperature inside the container reached above 50 °C when the ambient air temperature was around 30 °C. The container was built using epoxy glass to guarantee maximum heat penetration. Actual temperature measurement inside the container was measured in real time against ambient air temperature. We present a mathematical model for predication of maximum temperature at different positions inside the container and their relation to different ambient air temperature scenarios. The mathematical formulas used are based on the conservation laws and a good agreement of a full month of field measurements were obtained. Even in winter conditions in many of developing countries air temperature can maintain levels above 20 °C, which will produce temperature around 30 °C and viruses can reach levels below detection limit in maximum 3 h.


Asunto(s)
Descontaminación/métodos , Residuos Sanitarios , Residuos Sólidos , Luz Solar , Administración de Residuos/métodos , Países en Desarrollo , Humedad , Modelos Teóricos , Temperatura
6.
Arch Pediatr ; 28(2): 111-116, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33446429

RESUMEN

Meteorological parameters are important factors that have an influence on infectious diseases. The present study aimed to explore the correlation between the spread of COVID-19, temperature, and relative humidity. The effect of human-imposed control parameters in the form of lockdown on the dissipation of COVID-19 was also analysed. Data were collected on the three study variables - temperature, relative humidity, and lockdown period - from nine of the most infected cities worldwide as well as information on changes in the number of COVID-19 patients from the beginning to a specific point in the lockdown period. A generalised regression model was applied to explore the effect of temperature and relative humidity on the change in daily new cases of COVID-19. The regression analysis did not find any significant correlation between temperature, humidity, and change in number of COVID-19 cases. Analysis of the cities with wide-ranging temperature variations showed a negative correlation of COVID-19 transmission (P=0.079) with temperature, but a relatively non-significant correlation with relative humidity (P=0.198). The number of total deaths was also higher in low-temperature countries compared with high-temperature countries. The specific growth rate in COVID-19 cases was decreased by more than 66% after implementation of a lockdown. This growth rate was exponentially decreased over time through the proper implementation of lockdown. Analysis of the real-case scenario and application of predictive models showed that for New York, Lombardy, and Madrid more than 120 days of strict lockdown was required for complete control of the transmission of COVID-19.


Asunto(s)
/transmisión , Humedad , Temperatura , /epidemiología , /prevención & control , Salud Global , Política de Salud , Humanos , Modelos Teóricos , Factores de Riesgo
7.
Environ Sci Pollut Res Int ; 28(6): 6267-6288, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33387315

RESUMEN

Coronavirus disease 2019 (COVID-19) has emerged as a significant public health emergency in recent times. It is a respiratory illness caused by the novel virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was initially reported in late December 2019. In a span of 6 months, this pandemic spread across the globe leading to high morbidity and mortality rates. Soon after the identification of the causative virus, questions concerning the impact of environmental factors on the dissemination and transmission of the virus, its persistence in environmental matrices, and infectivity potential begin to emerge. As the environmental factors could have far-reaching consequences on infection dissemination and severity, it is essential to understand the linkage between these factors and the COVID-19 outbreak. In order to improve our current understanding over this topic, the present article summarizes topical and substantial observations made regarding the influences of abiotic environmental factors such as climate, temperature, humidity, wind speed, air, and water quality, solid surfaces/interfaces, frozen food, and biotic factors like age, sex, gender, blood type, population density, behavioural characteristics, etc. on the transmission, persistence, and infectivity of this newly recognized SARS-CoV-2 virus. Further, the potential pathways of virus transmission that could pose risk to population health have been discussed, and the critical areas have been identified which merits urgent research for the assessment and management of the COVID-19 outbreak. Where possible, the knowledge gaps requiring further investigation have been highlighted.


Asunto(s)
Humanos , Humedad , Pandemias , ARN Viral
8.
Sensors (Basel) ; 21(1)2021 Jan 05.
Artículo en Inglés | MEDLINE | ID: mdl-33466505

RESUMEN

The design, micro-fabrication, and characterization of a resistance temperature detector (RTD) based micro sensor for minimally invasive breathing analysis and monitoring is presented. Experimental results demonstrate that the change in air temperature while inhaling and exhaling can be transduced into a time varying electrical signal, which is subsequently used to determine the breathing frequency (respiratory rate). The RTD is placed into a Wheatstone bridge to simultaneously reduce the sensor's output noise and improve overall system accuracy. The proposed design could potentially aid health care providers in the determination of respiratory rates, which is of critical importance during the current COVID-19 pandemic.


Asunto(s)
/epidemiología , Monitoreo Fisiológico/instrumentación , Respiración , /fisiopatología , Diseño de Equipo , Humanos , Humedad , Pandemias , Temperatura
9.
Life Sci ; 269: 119093, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33476630

RESUMEN

BACKGROUND: Coronavirus disease 2019 (COVID-19) has become a severe public health problem around the globe. Various epidemiological, statistical, and laboratory-based studies have shown that the role of temperature and other environmental factors has important influence in the transmission of coronaviruses. Scientific research is needed to answer the questions about the spread and transmission of the infection, whether people could be avoided from being infected with COVID-19 in next summer. AIM: We aim to investigate the association of daily average temperature, daily average dew point, daily average humidity, daily average wind speed, and daily average pressure with the infection caused by this novel coronavirus in Pakistan. KEY FINDINGS: First, we check the correlation between environmental factors and daily infected cases of COVID-19; among them, temperature and dew point have positive linear relationship with daily infected cases of COVID-19. The thought-provoking findings of the present study suggested that higher temperature and dew point can contribute to a rise in COVID-19 disease in four provinces of Pakistan, possible to genome modifications and viral resistance to harsh environment. Moreover, it is also observed that humidity in Punjab and Sindh, and wind speed in Balochistan and Khyber Pakhtunkhwa have influenced the spreading of daily infected COVID-19 cases. SIGNIFICANCE: Current study will serve as a guideline to develop understanding of environmental factors that influence COVID-19 spread, helping policymakers to prepare and handle a catastrophe resulting from this pandemic.


Asunto(s)
/epidemiología , Temperatura , Tiempo (Meteorología) , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Niño , Interpretación Estadística de Datos , Femenino , Humanos , Humedad , Masculino , Persona de Mediana Edad , Pakistán/epidemiología , Viento , Adulto Joven
10.
Sci Rep ; 11(1): 1981, 2021 01 21.
Artículo en Inglés | MEDLINE | ID: mdl-33479261

RESUMEN

To determine the factor triggering the sudden surge of daily new COVID-19 cases arising in most European countries during the autumn of 2020. The dates of the surge were determined using a fitting of the two last months of reported daily new cases in 18 European countries with latitude ranging from 39° to 62°. The study proves no correlation between the country surge date and the 2 weeks preceding temperature or humidity but shows an impressive linear correlation with latitude. The country surge date corresponds to the time when its sun UV daily dose drops below ≈ 34% of that of 0° latitude. Introducing reported seasonal blood 25-hydroxyvitamin D (25(OH)D) concentration variation into the reported link between acute respiratory tract infection risk and 25(OH)D concentration quantitatively explains the surge dynamics. Several studies have already substantiated a 25(OH)D concentration impact on COVID-19 severity. However, by comparing different patient populations, discriminating whether a low 25(OH)D concentration is a real factor underlying COVID-19 severity or only a marker of another weakness that is the primary severity factor can be challenging. The date of the surge is an intrapopulation observation and has the benefit of being triggered only by a parameter globally affecting the population, i.e. decreases in the sun UV daily dose. The results indicate that a low 25(OH)D concentration is a contributing factor to COVID-19 severity, which, combined with previous studies, provides a convincing set of evidence.


Asunto(s)
/sangre , Vitamina D/análogos & derivados , /transmisión , Suplementos Dietéticos , Europa (Continente)/epidemiología , Geografía , Humanos , Humedad , /patogenicidad , Estaciones del Año , Luz Solar , Temperatura , Vitamina D/sangre , Tiempo (Meteorología)
11.
J Chromatogr A ; 1638: 461830, 2021 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-33453655

RESUMEN

The use of chromatographic methods in routine analysis includes System Suitability Tests (SST). This paper presents a novel approach to SST in HPTLC, which allows qualification of the entire RF range of an HPTLC plate independently of the samples. It is based on the Universal HPTLC mix (UHM), a pre-defined mixture of eight reference substances: guanosine, sulisobenzone, thymidine, paracetamol, phthalimide, 9-hydroxyfluorene, thioxanthen-9-one, and 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, selected to cover a broad range of polarities and functional groups. The chromatographic behavior of the UHM was evaluated for 20 different mobile phases on Silica gel 60 F254. At least three constituents were baseline separated. In a collaborative trial with four laboratories the reproducibility of RF values for three representative mobile phases, was found to be within a confidence interval of 0.040 RF units. The response characteristics of the UHM were assessed with respect to changes in chromatographic conditions, such as variation of the relative humidity, improperly employed saturation, or mistakes in the preparation of the mobile phase. Based on the RF values of the individual constituents significant responses were found for most changes. This qualifies the UHM for use in SST.


Asunto(s)
Cromatografía en Capa Delgada/métodos , Humedad , Reproducibilidad de los Resultados , Espectrofotometría Ultravioleta
12.
Proc Natl Acad Sci U S A ; 118(1)2021 01 07.
Artículo en Inglés | MEDLINE | ID: mdl-33323525

RESUMEN

With nearly every country combating the 2019 novel coronavirus (COVID-19), there is a need to understand how local environmental conditions may modify transmission. To date, quantifying seasonality of the disease has been limited by scarce data and the difficulty of isolating climatological variables from other drivers of transmission in observational studies. We combine a spatially resolved dataset of confirmed COVID-19 cases, composed of 3,235 regions across 173 countries, with local environmental conditions and a statistical approach developed to quantify causal effects of environmental conditions in observational data settings. We find that ultraviolet (UV) radiation has a statistically significant effect on daily COVID-19 growth rates: a SD increase in UV lowers the daily growth rate of COVID-19 cases by ∼1 percentage point over the subsequent 2.5 wk, relative to an average in-sample growth rate of 13.2%. The time pattern of lagged effects peaks 9 to 11 d after UV exposure, consistent with the combined timescale of incubation, testing, and reporting. Cumulative effects of temperature and humidity are not statistically significant. Simulations illustrate how seasonal changes in UV have influenced regional patterns of COVID-19 growth rates from January to June, indicating that UV has a substantially smaller effect on the spread of the disease than social distancing policies. Furthermore, total COVID-19 seasonality has indeterminate sign for most regions during this period due to uncertain effects of other environmental variables. Our findings indicate UV exposure influences COVID-19 cases, but a comprehensive understanding of seasonality awaits further analysis.


Asunto(s)
/epidemiología , Pandemias , Rayos Ultravioleta , /virología , Humanos , Humedad , Estaciones del Año , Temperatura
13.
Food Chem ; 334: 127548, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-32712487

RESUMEN

The study examined the influence of the process of extrusion on the physical properties and nutritional composition of black chokeberry pomaces. It has been determined that the extrusion process resulted in a reduction of the content of anthocyanins and fibre, but an increase of the contribution of simple sugars. In order to assess the phase transitions occurring in the products, a state diagram was utilized, which was constructed using the freezing and vitrification curve and values characterizing the conditions of maximum cryoconcentration. The determined values of critical water activity (based on water activity concepts) indicate that pomaces and extrudates retain crispiness in storage under moderate environmental relative humidity conditions. However, in the case of the glass transition concept, the determined values of water activity indicate that products stored in room temperature must be protected against the influence of humidity.


Asunto(s)
Almacenamiento de Alimentos/métodos , Photinia/química , Adsorción , Humedad , Transición de Fase , Photinia/metabolismo , Temperatura , Temperatura de Transición , Agua/química
14.
Sci Total Environ ; 751: 141663, 2021 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-32866831

RESUMEN

Beyond the contact and respiratory transmission of the COVID-19 virus, it has recently been reported in the literature that humidity, temperature, and air pollution may be effective in spreading the virus. However, taking the measurements regionally suspects the accuracy or validity of the data. In this research, climate values (temperature, humidity, number of sunny days, wind intensity) of 81 provinces in Turkey were collected in March 2020. Also, the population, population density of the provinces, and average air pollution data were taken. The findings of the study showed that population density and wind were effective in spreading the virus and both factors explained for 94% of the variance in virus spreading. Air temperature, humidity, the number of sunny days, and air pollution did not affect the number of cases. Besides, population density mediated the effect of wind speed (9%) on the number of COVID-19 cases. The finding that COVID-19 virus, invisible in the air, spreads more in windy weather indicates that the virus in the air is one threatening factor for humans with the wind speed that increases air circulation.


Asunto(s)
Infecciones por Coronavirus , Pandemias , Neumonía Viral , Viento , Betacoronavirus , Ciudades , Humanos , Humedad , Densidad de Población , Temperatura , Turquia/epidemiología
15.
Sci Total Environ ; 751: 141779, 2021 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-32890800

RESUMEN

Climate change is a major world-wide challenge to livestock production because food security is likely to be compromised by increased heat stress of the animals. The objective of this study was to characterize, using bioclimatic indexes, two livestock regions located in an arid zone of México, and to use this information to predict the impact of global warming on animal production systems of these regions located in the state of Baja California (México). A 5-year database (i.e., 2011 to 2015) consisting of about one million data points from two zones (i.e., coast, valley) from four meteorological stations in the north of Baja California were used. Bioclimatic indexes were constructed for the four types of livestock production systems most common in this region, being: dairy cattle, beef cattle, sheep, pigs. The temperature-humidity index (THI) thresholds used to classify heat stress were determined and scaled for each livestock species as: THIbeef and THIpig 74 units; THImilk 72 units; and THIsheep 23 units. Statistical differences between indices were detected (P < 0.01) during summer for the valley and coast zones as (THIbeef = 72.9 and 51.8; THImilk = 80.6 and 67.4; THIpigs = 83.9 and 65.2; THIsheep = 29.5 and 20.1 units). Coast zone weather did not suggest vulnerability of livestock production systems to heat stress at any time of the year, but heat stress risk during summer for valley zone dairy cattle, sheep and pigs was classified as severe, but lower for feedlot cattle. Prediction models showed significant adjustment just in the coastal zone for THImilk, THIsheep, and THIsheep, suggesting more impact of global warming during summer in the coastal zone. Use of management strategies to reduce heat load of domestic animals during summer in northern Baja California is essential to maintain their productivity, with more emphasis in the valley zone.


Asunto(s)
Cambio Climático , Trastornos de Estrés por Calor , Animales , Bovinos , Trastornos de Estrés por Calor/veterinaria , Calor , Humedad , Ganado , México , Ovinos , Porcinos
16.
Sci Total Environ ; 759: 144312, 2021 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-33333330

RESUMEN

At the beginning of the SARS-COV-2 outbreak in Brazil, there was a striking difference between the contamination rate in the Amazonian States and the South and the Southeast States. The regions near the Amazon rainforest presented much higher and faster contaminations. This paper attempts to explain this phenomenon through a global analysis of the COVID-19 epidemic in Brazil. It also investigates the relationship between climate conditions and airborne transmission with the evolution of contagion in the Amazonian states. The method of investigation of the spread of SARS-COV-2 in these different macro-environments was based on the analysis of three extensive daily official databases on the number of deaths, the percentage of adherence of the populations to the restriction policies, and the local climatic conditions. Besides, the social conditions in those States were also taken into account. Then, it was compared the epidemiologic results for States with very different climatic characteristics and that had adopted, almost simultaneously, similar social isolation measures. However, all these analyses were not able to explain the remarkable difference in the evolution of the pandemic among Brazilian regions. So, it was necessary to invoke airborne transmission, facilitated by the very high air humidity, as a decisive factor to explain the faster evolution of contagion in the rainforest region. Air humidity seems to be the most important climatic factor in viral spreading, while usual ambient temperatures do not have a strong influence. Another very important result of this analysis was the observation that the onset of collective immunity may have been achieved with a contamination rate of about 15% of the Amazonian population.


Asunto(s)
Brotes de Enfermedades , Brasil/epidemiología , Humanos , Humedad , Bosque Lluvioso , Temperatura
17.
Chemosphere ; 263: 128002, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32846290

RESUMEN

Air pollution in metropolises is one of the serious problems of human life. Tehran is one of the cities facing air pollution problem. Urban managers concern about choosing different management methods to control air pollution. In this study, a combination of fuzzy systems and neural networks has been used to select the most suitable scenario for controlling SO2 pollution. According to the method presented in this paper, 8 input data categories such as wind speed, precipitation, temperature, pressure, humidity, gas oil consumption, gasoline consumption and urban green space levels have been used as independent parameters and SO2 pollutant concentration has been considered as the dependent parameter. The contribution of each meteorological station to the meteorological data was determined by Thiessen Polygon Method. Then, using adaptive neural fuzzy inference systems, modeling was done in Sugeno Method and the least root mean square error (3.19) was determined for the model. Then, by changing each of the independent parameters, the effect of each of these independent parameters on SO2 pollutant was measured. The results showed that the parameters of pressure, urban green space, gasoline consumption, gas oil consumption, temperature, wind speed and humidity, respectively, had the greatest effect on reducing the SO2 concentration. Since the parameters of gasoline and gas oil consumption as well as the area of green space are changeable by different policies and by human decisions, the concentration of SO2 pollutant can be controlled by reducing the consumption of gasoline and gas oil and increasing the green space in Tehran.


Asunto(s)
Contaminantes Atmosféricos/análisis , Contaminación del Aire/estadística & datos numéricos , Monitoreo del Ambiente/métodos , Dióxido de Azufre/análisis , Contaminación del Aire/análisis , Ciudades , Humanos , Humedad , Irán , Redes Neurales de la Computación , Material Particulado/análisis , Temperatura , Viento
18.
Food Chem ; 339: 128097, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-32979715

RESUMEN

The cuticular wax of Korla pear stored under different relative humidity (0 ± 1 ℃, 50-55%, 70-75% and 90-95%) was examined in terms of total wax content, chemical composition and crystal morphology. The cuticular wax was composed of alkanes, olefins, fatty acids, alcohols, aldehydes, esters and terpenoids. High humidity maintained the content of total wax, alkanes and aldehydes at sufficient levels, especially C29 alkane and C18 aldehyde, which could positively regulate the quality of the pear fruits. Cuticular wax contributes to the capacity of preserving water, maintaining cell wall and delaying senescence. Scanning electron microscopy showed that wax crystals appeared as numerous platelets with irregular ovate crystals, high humidity delayed the transformation of wax structure. Taken together, high humidity delayed the ripening and aging by effectively maintaining wax, which was essential for postharvest storage and provide a reference for the production of synthetic wax for Korla pear fruits.


Asunto(s)
Almacenamiento de Alimentos/métodos , Frutas/química , Pyrus/química , Ceras/química , Alcoholes/análisis , Aldehídos/análisis , Alcanos/química , Ácidos Grasos/análisis , Humedad , Refrigeración , Terpenos/análisis
19.
J Environ Sci (China) ; 100: 279-286, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33279040

RESUMEN

Atmospheric visibility can directly reflect the air quality. In this study, we measured water-soluble ions (WSIs), organic and element carbon (OC and EC) in PM2.5 from September 2017 to August 2018 in Urumqi, NW China. The results show that SO42-, NO3- and NH4+ were the major WSIs, together accounting for 7.32%-84.12% of PM2.5 mass. Total carbon (TC=OC+EC) accounted for 12.12% of PM2.5 mass on average. And OC/EC > 2 indicated the formation of secondary organic carbon (SOC). The levels of SO42-, NO3- and NH4+ in low visibility days were much higher than those in high visibility days. Relative humidity (RH) played a key role in affecting visibility. The extinction coefficient (bext) that estimated via Koschmieder formula with visibility was the highest in winter (1441.05 ± 739.95 Mm-1), and the lowest in summer (128.58 ± 58.00 Mm-1). The bext that estimated via IMPROVE formula with PM2.5 chemical component was mainly contributed by (NH4)2SO4 and NH4NO3. The bext values calculated by both approaches presented a good correlation with each other (R2 = 0.87). Multiple linear regression (MLR) method was further employed to reconstruct the empirical regression model of visibility as a function of PM2.5 chemical components, NO2 and RH. The results of source apportionment by Positive Matrix Factorization (PMF) model showed that residential coal combustion and vehicle emissions were the major sources of bext.


Asunto(s)
Contaminantes Atmosféricos , Material Particulado , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , China , Monitoreo del Ambiente , Humedad , Luz , Material Particulado/análisis , Estaciones del Año
20.
Sci Total Environ ; 761: 144432, 2021 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-33360124

RESUMEN

Environmental factors are well known to affect spatio-temporal patterns of infectious disease outbreaks, but whether the rapid spread of COVID-19 across the globe is related to local environmental conditions is highly debated. We assessed the impact of environmental factors (temperature, humidity and air pollution) on the global patterns of COVID-19 early outbreak dynamics during January-May 2020, controlling for several key socio-economic factors and airport connections. We showed that during the earliest phase of the global outbreak (January-March), COVID-19 growth rates were non-linearly related to climate, with fastest spread in regions with a mean temperature of ca. 5 °C, and in the most polluted regions. However, environmental effects faded almost completely when considering later outbreaks, in keeping with the progressive enforcement of containment actions. Accordingly, COVID-19 growth rates consistently decreased with stringent containment actions during both early and late outbreaks. Our findings indicate that environmental drivers may have played a role in explaining the early variation among regions in disease spread. With limited policy interventions, seasonal patterns of disease spread might emerge, with temperate regions of both hemispheres being most at risk of severe outbreaks during colder months. Nevertheless, containment measures play a much stronger role and overwhelm impacts of environmental variation, highlighting the key role for policy interventions in curbing COVID-19 diffusion within a given region. If the disease will become seasonal in the next years, information on environmental drivers of COVID-19 can be integrated with epidemiological models to inform forecasting of future outbreak risks and improve management plans.


Asunto(s)
Clima , Brotes de Enfermedades , Humanos , Humedad
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