No abstract

Graphical abstract

Graphical abstract

No abstract

In the indoor environment of dental clinics, dental personnel and patients are exposed to a risk of infection because of the transmission of SARS-CoV-2 via particles or droplets. This study investigated the presence of SARS-CoV-2 RNA in indoor air of dental clinics in Tehran, Iran. Air sampling was done ( n = 36) collecting particulate samples on PTFE filters at flow rates of 30 to 58 L/min. The samples were analyzed with novel coronavirus nucleic acid diagnostic real-time PCR kits. Only 13 out of 36 samples were positive for SARS-CoV-2 RNA. Logistic regression showed that sampling site’s volume, PM 2.5 concentration, number of people, and number of active patient treatment units were significantly positively related with the presence of SARS-CoV-2 RNA. Thus, strategies to control the spread of COVID-19 should include reducing the number of infected people in dental clinics, adding filtration systems, and/or improving ventilation conditions.

Purpose The aim of the present study was to investigate the effect of short-term exposure to ambient black carbon (BC) on daily causespecific mortality, including mortality due to respiratory, cardiovascular, ischemic heart and cerebrovascular diseases in Tehran, Iran. Materials and methods Daily non-accidental death counts, meteorological data and hourly concentrations of air pollutants from 2014 to 2017 were collected in Tehran. A distributed lag non-linear model was used to assess the association between exposure to BC and daily mortality. ResultsThe mean daily BC concentration during the study period was 3.96 ± 1.19 µg/m 3 . The results indicated that BC was significantly associated with cardiovascular, ischemic heart disease, and cerebrovascular mortality, but not with respiratory mortality. In first model, each 10 µg/m 3 increase in at lag 3, lag 4 and lag 5 were associated with cardiovascular mortality in 16-65 year age group with the relative risks (RRs) of 1.17 (95 % CI: 1.02-1.33), 1.17 (95 % CI: 1.04-1.31) and 1.12 (95 % CI: 1.02-1.24), respectively. The highest mortality rate per 10 µg/m 3 increase in exposure was found for ischemic heart diseases with RR of 3.98 (95 % CI: 1.04-1.81, lag 01) for 16-65 age group. Cerebrovascular mortality was associated with 10 µg/m 3 increases in non-cumulative exposure with RR of 1.17 (95 % 1.009-1.35, lag 5) in the age group ≥ 65 years. In the second model for a 10 µg/m 3 increase in BC, cardiovascular mortality at specific lag days (5 and 6 days) in the age group ≤ 16 years were associated with RR of 1.34 (95 % CI 1.08-1.66) and 1.35(95 % CI 1.02-1.77), respectively. Conclusions This study in Tehran found significant effects of BC exposure on daily mortality for cardiovascular, ischemic heart disease, cerebrovascular disease.

No abstract

This study investigated the association of short-term exposure to PM 10 , PM 2.5 , NO 2 , O 3 , and CO with daily all-cause, cardiovascular, ischemic heart disease (IHD), cerebrovascular, and respiratory deaths in Mashhad, a tourist megacity in Iran (2014Iran ( -2018. A distributed-lag-day, nonlinear model (DLNM) and generalized additive model (GAM) based on the quasi-Poisson distribution were used to explore the exposure-lag-day-response associations. The average (± standard deviation) concentrations of PM 10 , PM 2.5 , NO 2 , O 3 , and CO were 67.1 (± 35.5), 29.6 (± 14.2), 57.3 (± 24.1), 55.9 (± 16.9), and 1907.6 (± 1362.7) μg/m 3 , respectively. NO 2 was associated with IHD mortality in lag-days 0 to 0-7, and lag-day 1. The relative risks (RRs) for a 10 μg/m 3 increase in NO 2 ranged from 1.01 (95% CI 0.93, 1.11) at lag-day 0 to 1.04 (95% CI 0.94, 1.16) and 1.03 (95% CI 0.93, 1.14) for lag-day 0-1 (cumulative) and lag-day 1 (non-cumulative), respectively. For all-cause mortality, cumulative exposure to PM 2.5 for lag-day 0-7 (1.07, 95% CI 1.00, 1.15) and non-cumulative exposure to NO 2 at lag-day 6 (1.02, 95% CI 1.00, 1.03) were significant. Exposure to PM 10 (per 10 μg/m 3 ) was significantly associated with respiratory mortality at several lag-days. Adjusting for Ramadan did not significantly affect the results. PM 10 had significant associations with respiratory mortality of people > 65 years old, and men for several lag-days. For IHD, NO 2 affected older people, and men and women over different lagdays. Results of multi-pollutant models were similar to the single-pollutant model outcomes. In conclusion, NO 2 and PM 10 had more significant relationships with adverse health outcomes than the other pollutants.