Critical air pollutant assessments and health effects attributed to PM2.5 during and after COVID-19 lockdowns in Iran: application of AirQ+ models.

Objectives: The aim of this study was to evaluate changes in air quality index (AQI) values before, during, and after lockdown, as well as to evaluate the number of hospitalizations due to respiratory and cardiovascular diseases attributed to atmospheric PM2.5 pollution in Semnan, Iran in the period from 2019 to 2021 during the COVID-19 pandemic. Methods: Daily air quality records were obtained from the global air quality index project and the US Environmental Protection Administration (EPA). In this research, the AirQ+ model was used to quantify health consequences attributed to particulate matter with an aerodynamic diameter of <2.5 µm (PM2.5). Results: The results of this study showed positive correlations between air pollution levels and reductions in pollutant levels during and after the lockdown. PM2.5 was the critical pollutant for most days of the year, as its AQI was the highest among the four investigated pollutants on most days. Mortality rates from chronic obstructive pulmonary disease (COPD) attributed to PM2.5 in 2019-2021 were 25.18% in 2019, 22.55% in 2020, and 22.12% in 2021. Mortality rates and hospital admissions due to cardiovascular and respiratory diseases decreased during the lockdown. The results showed a significant decrease in the percentage of days with unhealthy air quality in short-term lockdowns in Semnan, Iran with moderate air pollution. Natural mortality (due to all-natural causes) and other mortalities related to COPD, ischemic heart disease (IHD), lung cancer (LC), and stroke attributed to PM2.5 in 2019-2021 decreased. Conclusion: Our results support the general finding that anthropogenic activities cause significant health threats, which were paradoxically revealed during a global health crisis/challenge.

Alteration in angiotensin-converting enzyme 2 by PM1 during the development of emphysema in rats.

INTRODUCTION: Angiotensin-converting enzyme 2 (ACE2) provides an adhesion site for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Patients with COPD could have severe outcomes after SARS-CoV-2 infection. The objective of this study was to investigate ACE2 regulation by air pollution during the development of COPD. METHODS: Sprague Dawley rats were exposed to unconcentrated traffic-related air pollution for 3 and 6 months. We examined lung injury markers, oxidative stress, inflammation, emphysema, ACE2 and angiotensin II receptor type 1 (AT1) and 2 (AT2) in the lungs after exposure. RESULTS: Lung injury occurred due to an increase in permeability and lactate dehydrogenase cytotoxicity was observed after 6 months of exposure to fine particulate matter of <1 µm in aerodynamic diameter (PM1). An α1-antitrypsin deficiency and neutrophil elastase production with emphysema development were observed after 6 months of PM1 exposure. 8-isoprostane and interleukin-6 were increased after 3 and 6 months of PM1 exposure. Caspase-3 was increased after exposure to PM1 for 6 months. Upregulation of ACE2 was found after 3 months of PM1 exposure; however, ACE2 had decreased by 6 months of PM1 exposure. AT1 and AT2 had significantly decreased after exposure to PM1 for 6 months. Furthermore, smooth muscle hypertrophy had occurred after 6 months of PM1 exposure. CONCLUSIONS: In conclusion, short-term exposure to PM1 increased the ACE2 overexpression in lungs. Long-term exposure to PM1 decreased the ACE2 overexpression in emphysema. Air pollution may be a risk for SARS-CoV-2 adhesion during the development of COPD.

Medical mask versus cotton mask for preventing respiratory droplet transmission in micro environments.

The objective of this study was to investigate whether cotton mask worn by respiratory infection person could suppress respiratory droplet levels compared to medical mask. We recruited adult volunteers with confirmed influenza and suspected cases of coronavirus disease 2019 (COVID-19) to wear medical masks and self-designed triple-layer cotton masks in a regular bedroom and a car with air conditioning. Four 1-hour repeated measurements (two measurements for bedroom the others for car) of particles with a size range of 20-1000 nm measured by number concentrations (NC0.02-1), temperature and relatively humidity, and cough/sneeze counts per hour were conducted for each volunteer. The paired t-tests were used for within-group comparisons in a bedroom and in a car. The results showed that there was no significant difference in NC0.02-1 or cough/sneeze counts between volunteers with medical masks and cotton masks in a bedroom or a car. We concluded that the cotton mask could be a potential substitute for medical mask for respiratory infection person in microenvironment with air conditioning. Healthy people may daily use cotton mask in the community since cotton mask is washable and reusable.