Seasonal Variation of Tropospheric Ozone and Its Association with the Chemical and Meteorological Precursors in Delhi, India

In the present study, profile of tropospheric ozone and its variation with its chemical and meteorological precursors has been assessed in Delhi. The ambient air of Anand Vihar ISBT was found to be mainly dominated by NOx (335 ug/m3) and BTX (Benzene-12.2 ug/m3, Toluene -37 ug/m3 and pXylene -8.2 ug/m3) amongst the selected sites of Delhi. NOx was found to be predominately high due to high vehicular traffic, fireworks during festivals and crop burning in and around Delhi during November 2015. The concentration of benzene was exceeding the permissible standards in all the selected sites of Delhi. The study also revealed that the highest annual concentration of tropospheric Ozone (56.2 ± 23.5 ug/m3 ) was reported from Punjabi Bagh among the selected sites of Delhi and was recorded primarily in summers (March 2016-June 2016). The results indicate that higher temperature, lower humidity and high intensity of solar radiation contribute to the formation of tropospheric ozone in Delhi. The minimum concentration of ozone was recorded during the monsoons (July, 2016-September, 2016). This indicates the high humidity, large cloud cover, low intensity of solar radiation which could have been the reason for slowdown of the photochemical process. A positive correlation was observed between tropospheric ozone and ambient temperature in Delhi

Threat to the groundwater from municipal landfills sites in Delhi, India

Threat to the groundwater from municipal landfills sites in Delhi, Indi

Urban local air quality management framework for non-attainment areas in Indian cities

© 2017 Elsevier B.V. Increasing urban air pollution level in Indian cities is one of the major concerns for policy makers due to its impact on public health. The growth in population and increase in associated motorised road transport demand is one of the major causes of increasing air pollution in most urban areas along with other sources e.g., road dust, construction dust, biomass burning etc. The present study documents the development of an urban local air quality management (ULAQM) framework at urban hotspots (non-attainment area) and a pathway for the flow of information from goal setting to policy making. The ULAQM also includes assessment and management of air pollution episodic conditions at these hotspots, which currently available city/regional-scale air quality management plans do not address. The prediction of extreme pollutant concentrations using a hybrid model differentiates the ULAQM from other existing air quality management plans. The developed ULAQM framework has been applied and validated at one of the busiest traffic intersections in Delhi and Chennai cities. Various scenarios have been tested targeting the effective reductions in elevated levels of NOx and PM2.5 concentrations. The results indicate that a developed ULAQM framework is capable of providing an evidence-based graded action to reduce ambient pollution levels within the specified standard level at pre-identified locations. The ULAQM framework methodology is generalised and therefore can be applied to other non-attainment areas of the country

A randomised clinical study to compare the haemodynamic effects of etomidate with propofol during induction of general anaesthesia

Background: Induction agents are frequently associated with changes in heart rate and blood pressure and various adverse effects. Since the introduction of general anaesthesia, no ideal induction agent has yet been discovered in term of providing a stable hemodynamic with fewer adverse effects. This prospective randomized clinical study was conducted to compare propofol and etomidate for their effect on hemodynamic and various adverse effects on patients scheduled for elective surgeries during the induction of general anesthesia.Methods: 50 patients of ASA I and II of age group 18-60 years scheduled for elective surgeries under general anaesthesia were randomly assigned in two groups (n=25) receiving etomidate (0.3 mg/kg) in group E and propofol (2.5 mg/kg) in group P as an induction agent. Hemodynamic parameters were recorded at various time intervals. Any adverse effect pain on injection and myoclonus was carefully watched. VAS score was recorded for pain on injection. Statistical analysis was done using software (SPSS IBM version 20). P value was considered significant if (p0.05). Patients in propofol group showed significant fall of  systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MAP) and compared to etomidate (P<0.05).) Pain on injection was more in propofol group (P=0.021), While incidence of myoclonus activity was higher in etomidate group (P=0.0027).Conclusions: Etomidate is a better induction agent over propofol as it provides more hemodynamic stability and less pain on injection as compared to propofol

The influence of odd-even car trial on fine and coarse particles in Delhi

The odd-even car trial scheme, which reduced car traffic between 08.00 to 20.00 h daily, was applied from 1–15 January 2016 (winter scheme, WS) and 15–30 April 2016 (summer scheme, SS). The daily average PM2.5 and PM10 exceeded national standards, with highest concentrations (313 μg m–3 and 639 μg m–3, respectively) during winter and lowest (53 μg m–3 and 130 μg m–3) during the monsoon (June–August). PM concentrations during the trials can be interpreted either as reduced or increased, depending on the periods used for comparison purposes. For example, hourly average net PM2.5 and PM10 (after subtracting the baseline concentrations) reduced by up to 74% during the majority (after 1100 h) of trial hours compared with the corresponding hours during the previous year. Conversely, daily average PM2.5 and PM10 were higher by up to 3–times during the trial periods when compared with the pre–trial days. A careful analysis of the data shows that the trials generated cleaner air for certain hours of the day but the persistence of overnight emissions from heavy goods vehicles into the morning odd–even hours (0800–1100 h) made them probably ineffective at this time. Any further trial will need to be planned very carefully if an effect due to traffic alone is to be differentiated from the larger effect caused by changes in meteorology and especially wind direction

Covid-19 impact on air quality in megacities

Air pollution is among the highest contributors to mortality worldwide, especially in urban areas. During spring 2020, many countries enacted social distancing measures in order to slow down the ongoing Covid-19 pandemic. A particularly drastic measure, the "lockdown", urged people to stay at home and thereby prevent new Covid-19 infections. In turn, it also reduced traffic and industrial activities. But how much did these lockdown measures improve air quality in large cities, and are there differences in how air quality was affected? Here, we analyse data from two megacities: London as an example for Europe and Delhi as an example for Asia. We consider data during and before the lockdown and compare these to a similar time period from 2019. Overall, we find a reduction in almost all air pollutants with intriguing differences between the two cities. In London, despite smaller average concentrations, we still observe high-pollutant states and an increased tendency towards extreme events (a higher kurtosis during lockdown). For Delhi, we observe a much stronger decrease of pollution concentrations, including high pollution states. These results could help to design rules to improve long-term air quality in megacities.Comment: 13 pages. Preliminary version of Supplementary Information and open code available here https://osf.io/jfw7n/?view_only=9b1d2320cf2c46a1ad890dff079a2f6