The durability of negative effects of silver nanoparticles on seed germination and growth characteristics of Scots pine (Pinus sylvestris L.) in soil

This study was conducted on the stability of the inhibitory effects of Ag nano-particles on seed germination and growth characteristic of Scots pine (Pinus sylvestris L.) seeds planted in soil. The study was conducted as a factorial experiment in completely randomized design with 3 replications. Experimental factors were different concentrations of silver nano-particles and different planting dates after mixing Ag nano-particles with soil. The results showed significant differences of the evaluated traits amongst the experimental treatments. Moreover, increasing the concentration of silver nano-particles was shown to result in significant decrease in early growth characteristics compared to control in the all examined planting dates. The maximum reductions in the above mentioned traits were observed in 100 mg/kg silver nano-particles. The reduction for most of the studied traits started at 20 mg/kg silver nano-particles indicated the vulnerably of P. sylvstris to silver nano-particles. These findings showed that Ag nano-particles in the soil have inhibitory effects on seed germination and growth characteristics of P. sylvestris and the time progression decreased the inhibition and toxic effects of silver nanoparticles in soil. This reduction over time could be related to the decreasing silver mobility and bioavailability in the studied soil. Therefore, repeating the current experiment with different woody species and in different environments is recommended

Environmental air pollution and acute cerebrovascular complications: an ecologic study in Tehran, Iran

Background: In this study, we aimed to assess the association between air pollution and cerebrovascular complications in Tehran, one of the most air-polluted cities in the world, among different subgroups of patients with stroke in 2004. Methods : In this ecologic study, we calculated the daily average levels of different air pollutants including CO, NO X , SO 2 , O 3 , and PM 10 and also humidity and temperature on the day of stroke and 48 hours prior to stroke in 1 491 patients admitted with the diagnosis of stroke in eight referral hospitals in different areas of Tehran. Then, we evaluated the association between the rate of stroke admissions and the level of the selected pollutants, humidity, and temperature on the day of stroke and 48 hours prior to stroke among different subgroups of patients. Results : There was no significant association between the same-day level of the pollutants and the rate of stroke admissions, but an association was seen for their level 48 hours before stroke. These associations differed among different subgroups of age, sex, history of underlying diseases, and type of stroke. Same-day temperature had a reverse association in patients with hemorrhagic stroke and in patients without a history of heart disease or previous stroke. A direct significant association was seen for humidity level 48 hours before stroke in patients with a history of heart disease. Conclusions: It is inferred that air pollution has a direct association with the incidence of stroke and these association differs among different subgroups of patients. The results of this study are not time-dependant and can be generalized to different times and regions. Moreover, these results may be useful for environmental health policy makers

Health impact and related cost of ambient air pollution in Tehran

Ambient air pollution represents one of the biggest environmental risks to health. In this study, we estimated the avoidable mortality burden attributable to ambient air pollution in Tehran, and derived the economic impact associated with these health effects. Using PM; 2.5; data from ground-level air pollution measurements in Tehran, we estimated PM; 2.5; exposure for 349 neighborhoods in Tehran, by the Environmental Benefits Mapping and Analysis Program (BenMAP-CE). We considered five scenarios related to PM; 2.5; levels: an increase to 35 μg/m; 3; ; a reduction to 25 μg/m; 3; ; a reduction to 15 μg/m; 3; ; a reduction to 10 μg/m; 3; (the WHO's air quality guideline value); and a full roll-back, assuming a reduction to 2.4 μg/m; 3; . All scenarios used 2017 p.m.; 2.5; levels as a starting point. Using the concentration response function of the Global Exposure Mortality Model (GEMM), we estimated a total of 7146 (95% CI: 6596-7513) adult (age ≥25 years) deaths attributable to PM; 2.5; in 2017. The leading causes of death were ischemic heart disease (3437; 95% CI: 3315-3516), stroke (886; 95% CI: 693-1002), lower respiratory infections (531: 95% CI: 414-589), chronic obstructive pulmonary disease (364; 95% CI: 271-420), and lung cancer (274; 95% CI: 236-298). The estimated total annual economic benefit (2017) of reducing PM; 2.5; concentration levels to 2.4 μg/m; 3; was USD 0.591 (95% CI: 0.447-0.624) billion per year, using the value of a life year (VOLY) approach, and USD 2.894 (95% CI: 2.671-3.043) billion per year, using the value of a statistical life (VSL) approach