Changes in air quality in Mexico City, London and Delhi in response to various stages and levels of lockdowns and easing of restrictions during COVID-19 pandemic

The impacts of COVID-19 lockdown restrictions have provided a valuable global experiment into the extent of improvements in air quality possible with reductions in vehicle movements. Mexico City, London and Delhi all share the problem of air quality failing WHO guideline limits, each with unique situations and influencing factors. We determine, discuss and compare the air quality changes across these cities during the COVID-19, to understand how the findings may support future improvements in their air quality and associated health of citizens. We analysed ground-level PM₁₀, PM_2.5, NO₂, O₃ and CO changes in each city for the period 1st January to August 31, 2020 under different phases of lockdown, with respect to daily average concentrations over the same period for 2017 to 2019. We found major reductions in PM₁₀, PM_2.5, NO₂ and CO across the three cities for the lockdown phases and increases in O₃ in London and Mexico City but not Delhi. The differences were due to the O₃ production criteria across the cities, for Delhi production depends on the VOC-limited photochemical regime. Levels of reductions were commensurate with the degree of lockdown. In Mexico City, the greatest reduction in measured concentration was in CO in the initial lockdown phase (40%), in London the greatest decrease was for NO₂ in the later part of the lockdown (49%), and in Delhi the greatest decrease was in PM₁₀, and PM_2.5 in the initial lockdown phase (61% and 50%, respectively). Reduction in pollutant concentrations agreed with reductions in vehicle movements. In the initial lockdown phase vehicle movements reduced by up to 59% in Mexico City and 63% in London. The cities demonstrated a range of air quality changes in their differing geographical areas and land use types. Local meteorology and pollution events, such as forest fires, also impacted the results.

Development of multi-functional streetscape green infrastructure using a performance index approach

This paper presents a performance evaluation framework for streetscape vegetation. A performance index (PI) is conceived using the following seven traits, specific to the street environments - Pollution Flux Potential (PFP), Carbon Sequestration Potential (CSP), Thermal Comfort Potential (TCP), Noise Attenuation Potential (NAP), Biomass Energy Potential (BEP), Environmental Stress Tolerance (EST) and Crown Projection Factor (CPF). Its application is demonstrated through a case study using fifteen street vegetation species from the UK, utilising a combination of direct field measurements and inventoried literature data. Our results indicate greater preference to small-to-medium size trees and evergreen shrubs over larger trees for streetscaping. The proposed PI approach can be potentially applied two-fold: one, for evaluation of the performance of the existing street vegetation, facilitating the prospects for further improving them through management strategies and better species selection; two, for planning new streetscapes and multi-functional biomass as part of extending the green urban infrastructure.

Preparation, characterization and in vivo studies of proliposomes containing Cyclosporine A

The present study was undertaken to prepare proliposomes of Cyclosporine A (CsA) to increase its oral bioavailability. The proliposomes were prepared by spraying a solution of CsA, egg lecithin and cremophor EL in methanol-chloroform mixture onto directly compressible lactose (carrier) in a rotary evaporator. A dry free flowing powder of proliposomes was obtained. The dry proliposomal powder was characterized for surface morphology by scanning electron microscopy (SEM). Then the proliposomes were hydrated with distilled water to produce liposomes, which were characterized for particle size distribution, % drug entrapment, and morphological characteristics by transmission electron microscopy (TEM). The liposomes exhibited good entrapment of about 99%. The entrapment of CsA in liposomes was found to be dependent mainly on the drug:lipid ratio. Bioavailability studies were carried out for three different formulations of CsA i.e., free drug suspension; proliposomes derived liposomes and marketed formulation (Pannimun Bioral, Microemulsion) on male SD rats. The results of bioavailability studies indicated that the difference in the mean drug concentration of the free drug and the liposomes was found to be statistically significant (p < 0.05, p value is 0.032). The absorption constant for liposomal product was much greater (10.26 h(-1)) than for free drug solution (1.2 h(-1)) or the marketed sample of microemulsion (2.51 h(-1)) and the volume of distribution was found to be less for liposomes (7629.88 ml/kg) than that of the free drug solution (10971.92 ml/kg) and marketed microemulsion (9012.07 ml/kg). The results of these studies have shown that a stable proliposomal formulation of CsA for oral administration can be prepared which can be easily hydrated into liposomes from which CsA can exert its clinical effects with a better oral bioavailability.

Characteristics and health implications of fine and coarse particulates at roadside, urban background and rural sites in UK

Recent studies have pointed to evidence that fine particles in the air could be significant contributors to respiratory and cardiovascular diseases and mortality. Epidemiologists looking at the health effects of particulate pollution need more information from various receptor locations to improve the understanding of this problem. Detailed information on temporal, spatial and size distributions of particulate pollution in urban areas is also important for air quality modellers as well as being an aid to decision and policy makers of local authorities. This paper presents a detailed analysis of temporal and seasonal variation of PM(10) and PM(2.5) levels at one urban roadside, one urban background and one rural monitoring location. Levels of PM(10), PM(2.5) and coarse fraction of particulates are compared. In addition, particulate levels are compared with NO(2) and CO concentrations. The study concludes that PM(10) and PM(2.5) are closely related at urban locations. Diurnal variation in PM(2.5)/PM(10) ratio shows the influence of vehicular emission and movement on size distribution. This ratio is higher in winter than in summer, indicating a build-up or longer residence time of finer particulates or washout due to wet weather in winter. In the second part of this study, a disease burden analysis is carried out based on the dose-response relationships recommended by the UK Committee on the Medical Effects of Air Pollution. The disease burden analysis indicates that if Marylebone Road (MR) levels of PM(10) were prevalent all over London, it will result in around 2.5% increase in death rates due to all causes. Whereas, if Bloomsbury (BB) levels were prevalent in London, which is more likely to occur as this is more representative of the urban background environment to which people in London are likely to be exposed, the corresponding increase would be around 1.7%. Considering this, in London, at Bloomsbury levels, 973 deaths and 1515 respiratory hospital admissions (RHA) are attributable to PM(10) while 2140 RHA are attributable to NO(2). After deducting the disease burden due to background levels at Rochester (RC), PM(10) emission caused by anthropogenic activities in London equates to 273 additional deaths and 410 additional RHA, while NO(2) account for additional 1205 incidences of RHA.

Liquid crystalline pharmacogel based enhanced transdermal delivery of propranolol hydrochloride

A novel pharmacogel was developed for the enhanced transdermal delivery of propranolol hydrochloride (PH). The synthesized prodrugs, propranolol palmitate hydrochloride (PPH) and propranolol stearate hydrochloride (PSH) self-assembled to form gel simply upon mixing alcoholic solution of prodrug with an aqueous solution in a specified ratio. By varying the ratio of prodrug, alcohol and water, three-component phase diagram was constructed which revealed isotropic-gel-vesicular dispersion regions, respectively concomitant to increasing the ratio of water. The gel phase is termed 'Pharmacogel' and exhibits birefringence under plane-polarized light corroborating the presence of lamellar liquid crystals. The pharmacogel by virtue of high chemical potential gradient and improved physicochemical properties showed the enhanced in-vitro skin permeation flux of 51.5+/-3.7 and 42.5+/-3.1 microg/cm(2)/h from PPH and PSH gel, respectively, as compared to 1.9+/-0.1 microg/cm(2)/h for control; and decrease in lag time (1.8 and 2.8 h for PPH and PSH gel, respectively) compared to control (7.6 h) was observed. The admixing of egg lecithin (EL) in increasing ratio concomitantly decreased the flux values to 31.7+/-2.1 microg/cm(2)/h (at a mole ratio of 50:50 PPH:EL) and increased the lag time. In the gel containing 50% EL, the addition of span 40 and cholesterol slightly reduced the permeation while sodium deoxycholate and Tween-80 improved it. The plasma drug levels following transdermal application of control were low (C(max)=23 ng/ml) while in PPH gel, it increased with time reaching C(max) of 94 ng/ml at 8 h post-application of PPH gel (C(max) of 75 ng/ml at 12 h post application of PL5 gel) and maintained for longer times. The AUC(0-32 h) for PPH gel was much higher (1968 ng h/ml) than control (AUC(0-18 h) was 239 ng h/ml), while EL mixed gel also showed better absorption (AUC(0-32 h) was 1707 ng h/ml). The gel formulations also caused less irritation than control, while mixed gel showed least irritation. This novel self-assembled pharmacogel providing high transdermal permeation with many variables to regulate the delivery is therefore having a great potential in percutaneous delivery.

High-entrapment liposomes for 6-Mercaptopurine--a prodrug approach

Low entrapment of drugs into liposomes is a serious challenge in their commercial application. 6-Mercaptopurine (6-MP), an antineoplastic agent, is such a drug with low entrapment efficiency (EE). We devised their lipophilic derivatization as a means of enhancing EE by covalently coupling 6-MP with glyceryl monostearate (GMS) via a succinic anhydride spacer. This prodrug had an improved partition coefficient value of 25.16 compared to 1.22 for free drug, confirming higher lipophilicity. A hydrolysis rate study of prodrug indicated 2.90%, 12.5%, 24.1%, and 25.1% hydrolysis in phosphate buffered saline (PBS) (pH 7.4) and 10%, 20%, and 30% serum, respectively. Liposomes of phosphatidylcholine (PC)/sphingomyelin, cholesterol, and dicetyl phosphate bearing drug or prodrug were prepared by shaking by hand and sonication methods. The EE was found to increase from 1.92% for free drug to 91.8% for drug-conjugate. An in vitro cell line toxicity study on L1210 leukemia cells showed improved performance of liposome-encapsulated drug-conjugate compared to free drug. The plasma drug level profile following administration of free drug and the liposomal formulation containing prodrug (HE liposome) manifested a higher sustained level of the latter, which was further improved in case of sphingomyelin-containing liposomes (STHE liposome). The pharmacokinetic parameters revealed an increase in half-life, from 61 min to 120 min for the HE liposomes and 296 min for the STHE liposomes. Therefore, increased entrapment was made possible through lipophilic derivatization, and it was subsequently tested in vivo.

A new disease-burden method for estimating the impact of outdoor air quality on human health

Urban air quality is a serious problem, with an estimated 40 million people in Europe exposed to exceedences of existing WHO air-quality guidelines, with prospects of further declines in air quality due to projected growth in motor vehicle traffic. Air-quality management strategies, underpinned by legislation are attempting to combat this problem. To support such strategies, assessment of the costs and benefits of remedial measures is required, including an assessment of the impact of urban air quality on human health. This paper describes a disease burden estimation approach, developed to assess 'health gain' from recreational water quality improvement, and its application to urban air quality and incidence of respiratory disease. The method represents an improvement over existing disease-burden estimation techniques applied to air quality, in that by considering the probability density function of pollutant concentrations, improved estimates of exposure and hence disease burden, and also 'health gain' from air-quality improvement, are possible. Estimations of mortality advanced by fine particulate matter (PM10) are presented for five UK cities. Implications of the method for disease burden and air-quality standards are discussed. The utility of integrating the disease-burden assessment model with linked dynamic models of land-use, vehicle movement and pollutant dispersion, as a means to identify remedial strategic planning initiatives, is highlighted.

Niosomal delivery of 5-fluorouracil

Non-ionic surfactant vesicles (niosomes) have shown promise as cheap, chemically stable alternatives to liposomes. Niosomes of spans (Sorbitan monoesters) have shown promise of commercial exploitation. Hence, niosomes were prepared of 5-fluorouracil (FU) using different spans. Niomsomes were prepared by the hand shaking method (HSM), reverse phase evaporation (REV) and ether injection method (EIM) using a series of Spans, i.e. Span 20, 40, 60 and 80. HSM giving least permeable vesicles were used to study the effect of variables like type of Span, composition of lipid and total lipid concentration on entrapment efficiency (EE) and release rate. Span 40 and 60 released 40.9 and 37.1% drug in 6 h while Span 20 and 80 displayed 52.2 and 57.1% release, respectively in the same time. Niosomes of Span 40 showed a mean vesicle size of 8.1 microns, EE of 15.3 +/- 1.3% and released 78.6% drug in 6 h; inclusion of cholesterol reduced the vesicle size to 4.8 microns, EE to 12.3 +/- 0.9% and the release to 50.5% (in 6 h), while incorporation of dicetyphosphate further reduced the vesicle size to 3.87 microns, EE to 10.9 +/- 1.1% and reduced release to 40.9% (in 6 h). Increase in the amount of lipid used translated into an almost linear increase in EE. Biodistribution of drug in rats was modified on encapsulation. The concentration of niosomal drug in liver, lung and kidney was increased while it decreased in intestine compared to free drug solution following intravenous administration. The niosomal formulation displayed higher and sustained plasma drug level profile compared to free drug solution. Pharmacokinetic calculations revealed an increase in half-life, area under the curve and decrease in volume of distribution of the drug on encapsulation. Thus, the study suggests that niosomes can act as promising carriers for 5-Fluorouracil.