RESUMEN
Phase-wise variations in different aerosol (BC, AOD, PM1, PM2.5 and PM10), radiation (direct and diffused) and trace gases (NO, NO2, CO, O3, SO2, CO2 and CH4) and their associated chemistry during the COVID-19 lockdown have been investigated over a tropical rural site Gadanki (13.5° N, 79.2° E), India. Unlike most of the other reported studies on COVID-19 lockdown, this study provides variations over a unique tropical rural environment located at a scientifically strategic location in the Southern Indian peninsula. Striking differences in the time series and diurnal variability have been observed in different phases of the lockdown. The levels of most species that are primarily emitted from anthropogenic activities reduced significantly during the lockdown which also impacted the levels and diurnal variability of secondary species like O3. When compared with the same periods in 2019, short-lived trace gas species such as NO, NO2, SO2 which have direct anthropogenic emission influence have shown the reduction over 50%, whereas species like CO and O3 which have direct as well as indirect impacts of anthropogenic emissions have shown reductions up to 10%. Long-lived species (CO2 and CH4) have shown negligible difference (<1%). BC and AOD have shown reductions over 20%. Particulate Matter (1, 2.5 and 10) reductions have been in the range of 40 to 50% when compared to the pre-lockdown period. The changes in shortwave downward radiation at the surface, diffuse component due to the scattering and diffuse fraction have been +2.2%, -4.1% and -2.4%, respectively, in comparison with 2019. In contrast with the studies over urban environments, air quality category over the rural environment remained same during the lockdown despite reduction in pollutants level. All the variations observed for different species and their associated chemistry provides an excellent demonstration of rural atmospheric chemistry and its intrinsic links with the precursor concentrations and dynamics.
Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , COVID-19 , Radiación , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , Contaminación del Aire/análisis , Control de Enfermedades Transmisibles , Monitoreo del Ambiente , Gases , Humanos , India , Material Particulado/análisis , SARS-CoV-2RESUMEN
Black carbon (BC) aerosol emitted in incomplete combustion processes is known for causing warming in the climate system also poses serious health issues. Identification of the sources of BC is essential for the development of mitigation strategies to regulate their effects in changing climate. Among different observational and analytical techniques currently available, source apportionment methods based on optical measurements are relatively simple. For example, 'Aethalometer model' was developed based on Aethalometer observations. However, there are a few limitations with this model arising from assumption of wavelength and angstrom exponent pairs. We have developed an empirical method which also relies on Aethalometer observations named as 'Two alpha method' which assumes angstrom exponent from fossil fuel as 1 and estimates bio-mass fraction and angstrom exponent for bio-mass burning. This method has been applied to Aethalometer observations from five different locations (rural, semi-urban and urban) over Indian sub-continent to quantify sources of BC. Fossil fuel is found to be the major source of BC (â¼70%) irrespective of the location. Collocated measurements of Carbon Monoxide (CO) over rural site correlated well with derived bio-mass fraction. Results from this study demonstrated the capabilities of empirical method and shall provide spatio-temporal variability in sources of BC if applied to more locations.
Asunto(s)
Aerosoles/análisis , Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente/métodos , Hollín/análisis , Monóxido de Carbono/análisis , Clima , Combustibles Fósiles/análisis , IndiaRESUMEN
BACKGROUND: The endovascular approach of ablation of renal sympathetic nerves is found to be effective in the treatment of uncontrolled hypertension. We report here our experience with the procedure in eight patients with drug resistant hypertension. METHODS: We included patients in whom the blood pressure remained above 150/90 mmHg despite being on minimum three antihypertensive drugs. Radiofrequency ablation of the sympathetic nerves of both the renal arteries was done using conventional ablation catheters. The patients were followed at 1-month, 3 months and 6 months post procedure and blood pressure recorded. RESULTS: All patients underwent successful renal sympathetic denervation. The mean blood pressure of the patients was 181/102.5 mmHg before the procedure and the average requirement of antihypertensive drugs per day was 4. A significant reduction in both systolic and diastolic blood pressure was observed post procedure which sustained over the follow up period of six months. The mean blood pressure observed at 1-month, 3 and 6 months were 137.5/80 mmHg, 136/81 mmHg and 137.5/81 mmHg, respectively. The average requirement of the number of antihypertensives also was reduced to 2.5 at the end of 6 months. There were no procedural complications. CONCLUSION: Catheter based renal denervation causes substantial and sustained blood pressure reduction without serious adverse events in patients with resistant hypertension.