Study of the Behavior of Air Parcels, using PIXE, Hysplit and Wind Rose in the Metropolitan Zone of Toluca Valley, Mexico

Aim: The objective of this work was to determine the behavior of the trajectories of the air plots in two sites (San Mateo Atenco-(SM) and San Lorenzo Tepaltitlán-(SL)), in the atmosphere of the Metropolitan Zone of the Toluca Valley (MZTV). Methodology: In the atmosphere of the MZTV, using HYSPLIT a Backward trajectory direction analysis was performed from June 29 to July 8, 2021, considering for each day the summertime schedules of the center, indicating its Coordinated Universal Time (UTC). An ANOVA analysis (with a significance level of α=0.05) was performed for the concentrations of SM and SL obtained with PIXE, with the objective of seeing the equality of their behavior. Results: The behavior of the direction of the trajectories of the air plots in both sites is similar and the trajectories for the same day are the same in both sites but different on another day; It was determined that during night-day (19 to 12 h of the following day) the behavior is similar and changes during the remaining time, being variable. In general, the origin of the trajectories of the air plots for both sites of the MZTV is predominantly from the southeast, a situation that was confirmed with Wind Roses. Of the ANOVA analysis, the p-value was in all cases greater than the significance level of 0.05, the null hypothesis was accept, and it is possible to conclude that the elemental chemical composition of PM2.5 have equal means in both sites. Conclusion: Among other, it is possible to consider the behavior of meteorological parameters and thus take them into account for sampling studies of criteria pollutants such as PM2.5.

Pilot Study of Air Quality during Pre and Post COVID-19 Lockdown: An Inadvertent Assistance to the Environment

The main object of this study was to examine the levels of air quality in Karachi, Pakistan, before and during the 1st, 2nd and 3rd wave of lockdown period levied to control the spread of a novel coronavirus (COVID-19) in the environment of Karachi city. Momentous improvement in the air quality has been found during the ‘Lockdown’ being implemented due to the Corona Virus Disease (COVID -19) pandemic in Karachi city. Concentrations of trace gases and particulate matter were used to calculate the results according to the criteria of USEPA. We have analyzed data from fourteen different locations along the busy roads in commercial, residential and industrial areas of Karachi during the period of lockdown. Data were compared to the before lockdown (BL) and during the complete lockdown (CL 1stwave), smart lockdown (SL 2nd wave) and again complete lockdown (CL-2 3rd wave) of COVID pandemic. The results show drastic reductions in criteria pollutants (PM10, CO, SO2 and NOx) concentrations in all the selected area during lockdown period. This study explained the level of air quality and its relation to prepare alternative plans to mitigate the air pollutants and to improve the environment of urban areas.

Phase Wise Variation of Criteria Pollutants across India during COVID-19 Lockdown

The COVID-19 epidemic forced many countries around the world to lockdown completely. This occlusion influenced the atmospheric composition positively due to reduced anthropogenic activities. Recently, many studies across India have shown how the COVID-19 lockdown has affected air quality in different cities. However, these studies did not examine the phased percentage variation in air pollutant concentrations across different states of India. In this study, percentage variation in the concentration of five criteria pollutant, PM10, PM2.5, NO2, CO and Ozone were studied for 13 states across India during four phases of COVID-19 lockdown. A significant decrease in air pollutant levels was observed in all four phases, with phase 1 and phase 2 reporting a maximum decrease. PM10 and PM2.5, CO and NO2 showed a decrease in concentration in all states. Ozone showed a mixed response, with both increase and decrease recorded across states. During the COVID-19 lockdown period in India, AOD levels were reduced by 10.25%. This study will certainly help regulators set the guidelines and mitigation measures for appropriate control of air pollutants in different states in future.

Regional flow climatology for central Mexico (Queretaro): a first case study

A flow climatology was established for the Metropolitan Area of Queretaro (MAQ), in central Mexico, by analyzing four years (2014-2017) of back-trajectories generated using the HYSPLIT Model. Two flow regimes were found: one from June until September (rainy regime); the other from December to May (dry regime). October and November were considered transition months. Northeasterly flows were present throughout the year; in contrast, trajectories from the southwest were much less frequent and observed mainly during the dry regime. An analysis of the wind fields from the NARR database for a longer period of time (1979 – 2019), suggests that these results are representative of the average conditions of the atmosphere at the study site. Some of the northeasterly trajectories observed originate within a desertic region of the state of Queretaro, where several limestone mines are located. During the dry regime and transition months some clusters originate at the industrial area in Guanajuato, which includes the Salamanca refinery. As air transport of pollutants follow these paths, this analysis could be useful for identifying regional sources that affect the MAQ and possibly increase its air pollution load. In fact, the variability of criteria pollutants concentrations matched the flow regimes described above.

Long-Term (2003–2019) Air Quality, Climate Variables, and Human Health Consequences in Dhaka, Bangladesh

Long-term trends in air quality by studying the criteria pollutants (PM2.5, PM10, CO, O3, NO2, and SO2) and climate variables (temperature, surface pressure, and relative humidity) were depicted in this study. The 17-year (2003–2019) average values of PM2.5, PM10, CO, O3, NO2, and SO2 were 88.69 ± 9.76 μg/m3, 124.57 ± 12.75 μg/m3, 0.69 ± 0.06 ppm, 51.42 ± 1.82 ppb, 14.87 ± 2.45 ppb, and 8.76 ± 2.07 ppb, respectively. The trends among the ambient pollutants were increasingly significant (p < 0.05) except for O3 with slopes of 1.83 ± 0.15 μg/m3/year, 2.35 ± 0.24 μg/m3/year, 0.01 ± 0.002 ppm/year, 0.47 ± 0.03 ppb/year, and 0.40 ± 0.02 ppb/year for PM2.5, PM10, CO, NO2, and SO2, respectively. Pearson correlations revealed a significant association among the pollutants while a noteworthy correlation was observed between ambient pollutants and surface temperature. Principal component analysis (PCA) and positive matrix factorization (PMF) have been employed collectively to examine the main sources of the pollutants. PCA revealed similar trends for PMs and CO, as well as NO2 and SO2 being equally distributed variables. PMF receptor modeling resulted in attributing four sources to the pollutants. The factors inferred from the PMF modeling were signified as vehicular emissions, road/soil dust, biomass burning, and industrial emissions. The hazard quotient (HQ) values were not antagonistic (HQ < 1) in acute exposure levels for the three age groups (infants, children, and adults) while showing significant health risk (HQ > 1) in chronic exposure for infants and children. Children are identified as the worst sufferers among the age groups, which points to low breathing levels and high exposure to traffic pollution in Dhaka, Bangladesh.

Low-Emissions Technology Development for Auxiliary Power Unit Combustion Systems

The aircraft Auxiliary Power Unit (APU) is required to provide power to start the main engines, conditioned air and power when there are no facilities available and, most importantly, emergency power during flight operation. Given the primary purpose of providing backup power, APUs have historically been designed to be extremely reliable while minimizing weight and fabrication cost. Since APUs are operated at airports especially during taxi operations, the emissions from the APUs contribute to local air quality. There is clearly significant regulatory and public interest in reducing emissions from all sources at airports, including from APUs. As such, there is a need to develop technologies that reduce criteria pollutants, namely oxides of nitrogen (NOx), unburned hydrocarbons (UHC), carbon monoxide (CO) and smoke (SN) from aircraft APUs. Honeywell has developed a Low-Emissions (Low-E) combustion system technology for the 131-9 and HGT750 family of APUs to provide significant reduction in pollutants for narrow-body aircraft application. This article focuses on the combustor technology and processes that have been successfully utilized in this endeavor, with an emphasis on abating NOx. This paper describes the 131-9/HGT750 APU, the requirements and challenges for small gas turbine engines, and the selected strategy of Rich-Quench-Lean (RQL) combustion. Analytical and experimental results are presented for the current generation of APU combustion systems as well as the Low-E system. The implementation of RQL aerodynamics is well understood within the aero-gas turbine engine industry, but the application of RQL technology in a configuration with tangential liquid fuel injection which is also required to meet altitude ignition at 41,000 ft is the novelty of this development. The Low-E combustion system has demonstrated more than 25% reduction in NOx (dependent on the cycle of operation) vs. the conventional 131-9 combustion system while meeting significant margins in other criteria pollutants. In addition, the Low-E combustion system achieved these successes as a “drop-in” configuration within the existing envelope, and without significantly impacting combustor/turbine durability, combustor pressure drop, or lean stability.

Catalyst Modeling Challenges for Electrified Powertrains

To meet the upcoming CO2 reduction challenges, the further electrification of vehicle powertrains is indispensable. In combination with the post-Euro 6 requirements for criteria pollutants, the exhaust system is expected to be more complex to allow for extremely low emissions under all driving conditions, potentially involving technologies such as electrical heating and phase-change materials. The longer ‘zero-flow’ operation of the exhaust system in hybrid applications and the associated light-out risk have demanding accuracy requirements for heat loss calculations and require additional thermal management strategies. This paper discusses the additional challenges posed with regard to catalyst modeling in the boundary conditions of electrified vehicles and the necessary improvements that go beyond the state-of-the-art techniques. Most of the necessary improvements are linked to advanced 3D modeling of the exhaust system components accounting for free convection and radiative heat transfer. Modeling of electrically assisted heating is demonstrated using a new approach involving a combined 3D electrical–thermal solver. Heat retention technologies with use of phase-change materials are also accounted for in these new-generation models. Finally, the need for a tighter integration of these high-fidelity models into a vehicle simulation framework is discussed.

Social Insurance, Welfare Codes, and the Spread of Covid-19

This paper explores disparities in the effect of pollution on confirmed cases of Covid-19 based on counties’ socioeconomic and demographic characteristics. Using data on all US counties on a daily basis over the year 2020 and applying a rich panel data fixed effect model, we document that: 1) there are discernible social and demographic disparities in the spread of Covid-19. Blacks, low educated, and poorer people are at higher risks of being infected by the new disease. 2) The criteria pollutants including Ozone, CO, PM10, and PM2.5 have the potential to accelerate the outbreak of the novel coronavirus. 3) The disadvantaged population is more vulnerable to the effects of pollution on the spread of coronavirus. Specifically, the effects of pollution on confirmed cases become larger for blacks, low educated, and counties with lower average wages in 2019.