Air pollution concentration and period of the day modulates inhalation of PM2.5 during moderate- and high-intensity interval exercise

Physiological impacts of atmospheric pollution: Effects of environmental air pollution on exercise

In this review, we discuss some of the recent advances in our understanding of the physiology of the air pollution and exercise. The key areas covered include the effect of exercise intensity, the effects of pre-exposure to air pollution, acclimation to air pollution, and the utility of masks during exercise. Although higher intensity exercise leads to an increase in the inhaled dose of pollutants for a given distance traveled, the acute effects of (diesel exhaust) air pollution do not appear to be more pronounced. Second, exposure to air pollution outside of exercise bouts seems to have an effect on exercise response, although little research has examined this relationship. Third, humans appear to have an ability to acclimate to ground level ozone, but not other pollutants. And finally, masks may have beneficial effects on certain outcomes at low intensity exercise in pollution with significant levels of particles, but more study is required in realistic conditions.

Effects of Particulate Matter Inhalation during Exercise on Oxidative Stress and Mitochondrial Function in Mouse Skeletal Muscle

Particulate matter (PM) has deleterious consequences not only on the respiratory system but also on essential human organs, such as the heart, blood vessels, kidneys, and liver. However, the effects of PM inhalation on skeletal muscles have yet to be sufficiently elucidated. Female C57BL/6 or mt-Keima transgenic mice were randomly assigned to one of the following four groups: control (CON), PM exposure alone (PM), treadmill exercise (EX), or PM exposure and exercise (PME). Mice in the three-treatment group were subjected to treadmill running (20 m/min, 90 min/day for 1 week) and/or exposure to PM (100 μg/m3). The PM was found to exacerbate oxidative stress and inflammation, both at rest and during exercise, as assessed by the levels of proinflammatory cytokines, manganese-superoxide dismutase activity, and the glutathione/oxidized glutathione ratio. Furthermore, we detected significant increases in the levels of in vivo mitophagy, particularly in the PM group. Compared with the EX group, a significant reduction in the level of mitochondrial DNA was recorded in the PME group. Moreover, PM resulted in a reduction in cytochrome c oxidase activity and an increase in hydrogen peroxide generation. However, exposure to PM had no significant effect on mitochondrial respiration. Collectively, our findings in this study indicate that PM has adverse effects concerning both oxidative stress and inflammatory responses in skeletal muscle and mitochondria, both at rest and during exercise.

Detection of atmospheric aerosols and terrestrial nanoparticles collected in a populous city in southern Brazil

The main objective of this study is to analyze hazardous elements in nanoparticles (NPs) (smaller than 100 nm) and ultrafine particles (smaller than 1 µm) in Porto Alegre City, southern Brazil using a self-made passive sampler and Sentinel-3B SYN satellite images in 32 collection points. The Aerosol Optical Thickness proportion (T550) identification was conducted using images of the Sentinel-3B SYN satellite at 634 points sampled in 2019, 2020, 2021, and 2022. Focused ion beam scanning electron microscopy analyses were performed to identify chemical elements present in NPs and ultrafine particles, followed by single-stage cascade impactor to be processed by high-resolution transmission electron microscopy. This process was coupled with energy-dispersive X-ray spectroscopy and later analysis via secondary ion mass spectrometry. Data was acquired from Sentinel-3B SYN images, normalized to a standard mean of 0.83 µg/mg, at moderate spatial resolution (260 m), and modeled in the Sentinel Application Platform (SNAP) software v.8.0. Statistical matrix data was generated in the JASP software (Jeffreys's Amazing Statistics Program) v.0.14.1.0 followed by a K-means cluster analysis. The results demonstrate the presence of between 1 and 100 nm particles of the following chemical elements: Si, Al, K, Mg, P, and Ti. Many people go through these areas daily and may inhale or absorb these elements that can harm human health. In the Sentinel-3B SYN satellite images, the sum of squares in cluster 6 is 168,265 and in cluster 7 a total of 21,583. The use of images from the Sentinel-3B SYN satellite to obtain T550 levels is of great importance as it reveals that atmospheric pollution can move through air currents contaminating large areas on a global scale.

Assessment of particulate matter inhalation during the trip process with the considerations of exercise load

A Particulate Matter (PM) inhalation model considering exercise load is established to evaluate the impact of PM on residents' travel health. The study chooses PM detectors to collect PM concentrations at the various transportation space, including walking, bicycle, bus, taxi, and subway. A multiple linear regression model revised by road greening is utilized to study the influence factors that have a potential impact on the PM concentration. The air inhalation model with the consideration of exercise load can be acquired by connecting the heart rate (HR) and individual characteristics. The PM_2.5 and PM₁₀ inhalation for a complete trip of traveler can be estimated using the proposed model based on air inhalation per time unit, travel time, and PM concentration. The analysis results using the experimental data in Xi'an indicate that PM concentrations in taxi carriage, bus carriage, and subway carriage are significantly different from those obtained from environmental monitoring stations. However, the difference is not significant in the locations of sidewalk, non-motorized lane, taxi station, bus station, subway concourse, and subway platform. PM concentration and humidity in background environment have a positive influence on the increase of PM concentration in transportation environment, while temperature and wind speed are negative. The mean values of air inhalation per time unit for male and female using each mode are in the range of 9.6-26.8 L/min and 9.8-27.8 L/min, respectively. Exposure time in non-motorized transportation has a large effect on PM inhalation of travelers, walking connections and waiting in motorized transportation are the main contributing states to PM inhalation of travelers. The results of the study can be used to predict travelers' PM inhalation in completed trips, and provide recommendations for travelers to choose a healthier mode.

How do temperature, humidity, and air saturation state affect the COVID-19 transmission risk?

Environmental parameters have a significant impact on the spread of respiratory viral diseases (temperature (T), relative humidity (RH), and air saturation state). T and RH are strongly correlated with viral inactivation in the air, whereas supersaturated air can promote droplet deposition in the respiratory tract. This study introduces a new concept, the dynamic virus deposition ratio (α), that reflects the dynamic changes in viral inactivation and droplet deposition under varying ambient environments. A non-steady-state-modified Wells-Riley model is established to predict the infection risk of shared air space and highlight the high-risk environmental conditions. Findings reveal that a rise in T would significantly reduce the transmission of COVID-19 in the cold season, while the effect is not significant in the hot season. The infection risk under low-T and high-RH conditions, such as the frozen seafood market, is substantially underestimated, which should be taken seriously. The study encourages selected containment measures against high-risk environmental conditions and cross-discipline management in the public health crisis based on meteorology, government, and medical research.

Exposure to O3 and NO2 in physically active adults: an evaluation of physiological parameters and health risk assessment

The gaseous air pollutants ozone (O₃) and nitrogen dioxide (NO₂) have a large public health relevance and trigger environmental health risk. On the other hand, despite the health benefits, exercise practices might increase the susceptibility to air pollutants exposure. However, there are innumerous lifestyle factors besides physical activity habits that must be considered in the daily air pollution exposure and are still not fully comprehended. This study aimed to evaluate the effects of O₃ and NO₂ exposure on cardiorespiratory fitness, lipid accumulation product (LAP), and environmental health risk during the entire daily routine of physically active adults that exercise in outdoor and indoor environments. One hundred and twenty healthy young men were assigned to untrained (n = 52), indoor exercise (n = 36), and outdoor exercise (n = 32) groups, following their lifestyle exercise habits, and O₃ and NO₂ were assessed by personal monitoring. Exercised groups demonstrated higher healthy eating index (HEI) (p < 0.001), physical activity (PA) (p < 0.001), metabolic equivalent of task (MET) (p < 0.001), and peak oxygen uptake VO_2peak (p < 0.001), while outdoor group had lower LAP index (p < 0.001) and higher O₃ concentration (p = 0.0442). Environmental health risk demonstrated no difference (p > 0.05). The higher O₃ concentration was positively correlated with the risk quotient (p = 0.003) and MET (p = 0.020), and a negative correlation between LAP and VO_2peak was observed (p < 0.001). In conclusion, physically active individuals might have a lower risk of developing cardiovascular and metabolic diseases despite the higher O₃ concentration exposure, and the exposure during exercise did not represent an additional health risk.

Exposure to fine particulate matter partially counteract adaptations on glucose metabolism, oxidative stress, and inflammation of endurance exercise in rats

BACKGROUND

Long-term exposure to air pollution triggers metabolic alterations along with oxidative stress and inflammation, while exercise interventions are widely used to improve those parameters.

OBJECTIVE

Our study aimed to determine the effects of subchronic exposure to particulate matter 2.5 (PM_2.5) and endurance exercise training on glucose metabolism, oxidative stress, and inflammation of the heart and gastrocnemius muscle of rats.

MATERIAL AND METHODS

Thirty-two male Wistar rats were assigned to 4 experimental groups: Untrained; Endurance training (ET); Untrained + PM_2.5; Endurance training + PM_2.5. Rats exposed to air pollution received 50 µg of PM_2.5 via intranasal instillation daily for 12 weeks. Exercised groups underwent endurance training, consisting in running on an electronic treadmill (70% of maximal capacity, 5 days/week, 5 times/week) for 12 weeks. Glucose metabolism markers, redox state, and inflammatory variables were evaluated in the heart and gastrocnemius muscle.

RESULTS

ET and ET + PM_2.5 group had lower body mass gain and higher exercise capacity, and higher glycogen concentration in the heart and gastrocnemius muscle. In the heart, ET and ET + PM_2.5 groups had higher levels of GSH, and lower TBARS and TNF-α concentrations. In the gastrocnemius muscle, the ET group showed higher leptin and lower TBARS and IL-1β concentrations, ET and ET + PM_2.5 showed higher superoxide dismutase activity and ROS content.

CONCLUSION

PM_2.5 exposure partially blunts metabolic and inflammatory adaptations in heart and gastrocnemius muscle tissues induced by exercise training.

Impacts of Regional Speed Control Strategy Based on Macroscopic Fundamental Diagram on Energy Consumption and Traffic Emissions: A Case Study of Beijing

Numerous studies shown that particulate matter in the ambient environment has a significant impact on the health of the respiratory system. To understand the interrelationships between urban built environment, transportation operations and health, this study proposes an innovative approach that uses real-world GPS datasets to calculate energy consumption and emissions from transportation. The experiment used the traffic operation state in the Fourth Ring Road of Beijing as the research object and tested the impact of using the Regional speed optimization (RSO) strategy based on Macroscopic Fundamental Diagram (MFD) on energy consumption and emissions during peak hours. The impact of traffic emission on the health of roadside pedestrians is also considered. Changes in PM2.5 concentrations around four different built-up areas were calculated and compared. The computational experiments indicate that the PM2.5 pollutants exhausted by the traffic on the Ring Road during peak hours can reach up to 250 μg/m3, while the traffic emission on general roads near residential areas is only 50 μg/m3. Adopting Regional speed optimization can reduce the energy consumption of the road network by up to 18.8%. For roadside runners, the PM2.5 inhalation caused by night running in commercial and recreational areas is about 1.3-2.6 times that of night running in residential areas. Compared with morning or night running, the risk of respiratory disease caused by PM2.5 inhalation was about 10.3% higher than commuter running behavior. The research results provide a useful reference for energy conservation and emission reduction control strategies for different road types in cities and help existing cities to establish a traveler health evaluation system caused by traffic operation.

Physical Exercise in the Context of Air Pollution: An Emerging Research Topic

Physical exercise (PE) brings physiological benefits to human health; paradoxically, exposure to air pollution (AP) is harmful. Hence, the combined effects of AP and PE are interesting issues worth exploring. The objective of this study is to review literature involved in AP-PE fields to perform a knowledge-map analysis and explore the collaborations, current hotspots, physiological applications, and future perspectives. Herein, cluster, co-citation, and co-occurrence analysis were applied using CiteSpace and VOSviewer software. The results demonstrated that AP-PE domains have been springing up and in rapid growth since the 21st century. Subsequently, active countries and institutions were identified, and the productive institutions were mainly located in USA, China, UK, Spain, and Canada. Developed countries seemed to be the major promoters. Additionally, subject analysis found that environmental science, public health, and sports medicine were the core subjects, and multidimensional communications were forming. Thereafter, a holistic presentation of reference co-citation clusters was conducted to discover the research topics and trace the development focuses. Youth, elite athletes, and rural population were regarded as the noteworthy subjects. Commuter exposure and moderate aerobic exercise represented the common research context and exercise strategy, respectively. Simultaneously, the research hotspots and application fields were elaborated by keyword co-occurrence distribution. It was noted that physiological adaptations including respiratory, cardiovascular, metabolic, and mental health were the major themes; oxidative stress and inflammatory response were the mostly referred mechanisms. Finally, several challenges were proposed, which are beneficial to promote the development of the research field. Molecular mechanisms and specific pathways are still unknown and the equilibrium points and dose-effect relationships remain to be further explored. We are highly confident that this study provides a unique perspective to systematically and comprehensively review the pieces of AP-PE research and its related physiological mechanisms for future investigations.

Exercising under particulate matter exposure: Providing theoretical support for lung deposition and its relationship with COVID-19

The aim of the present study was to investigate lung particulate matter (PM) deposition during endurance exercise and provide a new insight concerning how SARS-CoV-2 could be carried into the respiratory tract. The anatomical and physiological characteristics of the Human Respiratory Tract model were considered for modeling the lung PM deposition during exercise. The Monte Carlo method was performed to randomly generate different values of PM concentrations (1.0, 2.5, and 10.0 μm), minute ventilation, and duration of exercise at moderate, heavy, and severe exercise intensity domains. Compared to moderate and severe intensities, during heavy exercise (75-115 L‧min-1, duration of 10.0-60.0 min) there is greater lung deposition in the bronchiolar region (p < 0.01). In turn, there is greater deposition per minute of exercise at the severe intensity domain (115.0-145.0 L‧min^-1, duration of 10.0-20.0 min, p < 0.01). Considering that SARs-CoV-2 could be adsorbed on the particles, exercising under PM exposure, mainly at the severe domain, could be harmful concerning the virus. In conclusion, beyond the traditional minute ventilation assumption, there is a time vs intensity dependence for PM deposition, whereby the severe domain presents greater deposition per minute of exercise. The results observed for PM deposition are alarming since SARs-CoV-2 could be adsorbed by particles and carried into the deeper respiratory tract.