Heavy metals levels in road dust from Muscat, Oman: relationship with traffic volumes, and ecological and health risk assessments.

Dust samples from roads classified based on traffic volumes (low, medium and high traffic) were collected from Muscat, Oman, and then analyzed for a dozen heavy metals. Their contents varied widely with mercury and iron, having the lowest and highest concentrations (0.59-0.80 and 406.10-429.00 ppm, respectively). Contrary to most metals detected, mercury and arsenic did not only exhibit increasing trends from low to high categories, but they also were significantly correlated to each other and traffic volumes, suggesting that both might originate from vehicular emissions. While the calculations revealed that the potential ecological risk index (RI) for selected metals in the dust samples was at a considerable level, the hazard index (HI) was within the safe threshold value (HI < 1). Overall, our findings imply minor prejudicial health risks to the general public nevertheless, children would be relatively more vulnerable to the impact of metals associated with dust.

Mass concentration and morphological analysis of PM10 and PM2.5 particles in congested roads during day hours in three major cities of Oman.

PM10 and PM2.5 samples were collected using the particulates E-Sampler from congested roads in three major cities of Oman. The average PM10 concentration varied from 35.87 µg/m3 in Salalah during the monsoon season to 18.95 µg/m3 in Sohar. PM2.5 concentration ranged from 20.74 µg/m3 in Muscat to 7.20 µg/m3 in Sohar. Average concentrations of PM10 and PM2.5 in all cities were below NAAQS and WHO standards. Scanning Electron Microscopy coupled with energy dispersive spectrometer (SEM-EDS) of PM2.5 particles from all cities showed spherical like fly ash and chain like soot aggregates. These might have originated from fuel burning and vehicle emissions. Fe, O and Si are the major components present in the PM2.5 and PM10 particles while other elements are present in lower percentages. PM10 particles collected from Muscat and Salalah were irregular and chain like soot aggregates that are referred to originate from natural and anthropogenic emissions. However, PM10 collected from Sohar showed irregular shape containing aluminosilicate particles that might have initiated from natural sources.

Characterization and exposure assessment to urban air toxics across Middle Eastern and North African countries: a review.

Middle East and North African (MENA) countries over the decades are experiencing rapid industrial and infrastructural growth combined with being the global hub of oil and gas industries. These economic transformations are associated with release of air pollutants including urban air toxics (UAT) through industrial, traffic, and constructional activities into ambient urban environments. UAT concentrations levels may exacerbate in most MENA countries considering high number of vehicular traffic populations and petrochemical industries which are one of the main sources of this pollutant. Therefore, the main objective of the study is to review major findings of UAT levels in urban areas across thirteen (13) MENA countries. The study characterizes various measured UAT, assesses their concentrations in ambient environment, and identifies their major sources of emissions by reviewing more than 100 relevant UAT papers across the selected MENA countries. It was found that benzene, heavy metals, formaldehyde, and dioxin-like compounds are the most reported UAT. The study concluded that road traffic, fuel stations, and petrochemical industries were identified as the main sources of ambient UAT levels. It was further reported that most of the studies were based on short-term ambient environment with limited studies in indoor environments. Therefore, it is highly recommended that future research should focus on innovative health impact assessment and epidemiological studies from exposure to UAT levels. Also embarking on sustainable mitigation approaches through urban greenery, eco-industrial estates infrastructural developments, and renewable energy shares will reduce UAT levels and improve human health.

Public awareness, perceptions and attitudes on air pollution and its health effects in Muscat, Oman.

A survey was conducted in Muscat/Oman between February and May of 2020, with a total of 1289 respondents to investigate public knowledge, behavior, and attitudes about the air pollution via online questionnaire. We considered the disparity among gender, age and education level in four main aspects, viz. sources of access to information, knowledge and risk perception about air pollution and willingness to change and act for mitigation. Social media was a primary source of access to information regarding air pollution in Muscat. Further, the majority of the respondents were aware of the meaning of air pollution and interested in the issue of air quality, while females have a higher level of air pollution awareness than males. Over 94% of respondents were disturbed by air pollution from vehicles and other sources. Males and older participants have significantly higher level of interest about air quality information. The majority pay attention to air quality when they move outdoors but females are more susceptible than males to the effects of air pollution. Majority recognized the air pollution is always dangerous to their health, yet participants with higher education level have a higher risk perception of air pollution. Breathing contaminated air was the most common pathway of exposure to the toxic air pollutants reported by participants. Over 90% of participants care about air quality when they are performing outdoor sports activities. Most of the participants reported that they did not use public transportation to move within Muscat Governorate, their major transportation mode being private vehicle. Meanwhile, females, older participants (over 35) and postgraduate holders significantly expressed their willingness to reduce the duration of driving vehicles.Implications: This work is the first study in the country that try to investigate perception, attitude and behavior of the public about air pollution in Muscat, the capital of Oman. Use of private vehicles is a popular mode of transportation in the city and is the major contributor to the air quality issues. Any future directions by the government toward sustainable transportation need a better understanding of people's perception on the issue. The results show that most of the respondents were aware of air quality and related issues and they also expressed willingness to change their behavior to reduce air pollution.

Human and ecological risk assessment of heavy metals in different particle sizes of road dust in Muscat, Oman.

Heavy metal contamination of Hg, As, Cu, Cr, Zn, and Pb was investigated in three different fractions 45, 125, and 200 µm of road dust in Muscat, Oman. Dust samples were collected from three different traffic roads, viz. high, medium, and low based on traffic volume and then sieved individually before they analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Cu has the highest level among the analyzed metals while the lowest amount was for Hg. Most of the metals in all traffic sites have higher concentration in finer fraction and the concentrations of Cu, Pb, and Zn in HT road dust decreased significantly from finer fraction (45 µm) to bigger fraction size (200 µm). The risks of analyzed heavy metals to the urban ecosystem and human health were calculated by the potential ecological risk index and human exposure model, respectively. Risk index levels of studied metals in the three fractions and roads vary from strong to very strong potential. Hg found to have the greatest contribution in risk index in the three different fractions and roads. The values of risk levels for individual metal contamination in the dust street samples from different roads and fractions were ranked in the following order: Hg > Cu > Pb > Cr > Zn. Ingestion is the main pathway of exposure to road dust particles for both children and adults, followed by dermal contact absorption. The HI for children and adults exposed to 45- and 125-µm particles were higher than exposed to 200-µm particles, which indicated that finer particles tend to have higher non-carcinogenic risk. The non-carcinogenic risks of the studied heavy metals to children and adults are within safe threshold value; however, health risks of Cr, Pb, and Cu were relatively high for children.

Occupational exposure to pesticides and associated health effects among greenhouse farm workers.

The number and production capacities of greenhouse farms have been increased across the globe, driven by an effort for addressing food security problems related to the rapid population growth and the effects of climate change. As a result, there was a large increase in the number of greenhouse farm workers who are typically involved in chemical preparations and pesticide sprayings, crop harvesting, and greenhouse maintenance activities. Considering the enclosed architecture of the greenhouse farm design and the frequent application of pesticides, the objective of this review was to characterize pesticide exposure levels and resultant health effects among greenhouse farm workers. While most health assessment studies were mainly based on self-reported symptoms, this review showed limited epidemiological and clinical studies on the assessment of the health effects of pesticide exposure on greenhouse workers' health. Reproductive disorders, respiratory symptoms, neurological symptoms, and skin irritations were the most reported health effects among greenhouse farm workers. Additionally, there were limited studies on respirable pesticide-borne fine and ultrafine particulate matters in greenhouse farms. Ventilation systems and indoor environmental conditions of greenhouse farms were not designed according to specifications of the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Among recommendations provided, long-term exposure assessments of pesticide effects on children born by greenhouse farm workers should be considered in future research. Also, compliance with ASHRAE indoor ventilation and environmental standards will be very important in reducing pesticide exposure and health effects among greenhouse farm workers.