The outbreak of human-human severe acute respiratory symptom coronavirus 2 (SARS-CoV-2) was initially reported in Wuhan city, Hubei Province, the Republic of China on 31st December 2019 (Chan et al. 2020). Since then, the SARS-CoV-2 has spread through almost every country within all the major regions/continents across the globe. As of 7 June 2020 in 10:15 GMT, the number of confirmed deaths caused by this virus was observed in Americas (183,999), Europe (178,761), Asia including Middle East (34, 587), and Africa (5,089), whereas these mortality cases also correspond to the same order of total confirmed cases found within each region (WHO 2020; Worldometer 2020).
The health and economic impacts from COVID-19 pandemic have been exacerbated mainly due to the introduction of stringent lockdown measures by several countries which have ultimately affected the global business cycles (Guan et al. 2020; Ozili and Arun 2020). Fortunately, the COVID-19 lockdown and social distancing measures have positively impacted environmental pollution levels through a reduction in air pollution, water pollution, and flooding situations in most countries (Lokhandwala and Gautam 2020; Muhammad et al. 2020). Several studies have reported a decrease in ambient air pollution levels during the COVID-19 lockdown. A study found that the air quality index (AQI) of various cities in China has decreased by 6.34 leading to a reduction in PM2.5 levels by 7 µg/m3(He et al. 2020). In India, which is rated as one of the highly polluted countries, it was found that there has been a reduction in AQI index by 31–54% among the PM, SO2, NO2, CO, O3, and NH3 in Delhi during COVID-19 lockdown. Similarly, Madrid and Barcelona experienced a significant reduction in ambient air quality by 62% and 50%, respectively where the study recommended the implementation of new air quality policies to help to achieve cleaner cities in the future (Baldasano 2020). Also, Saudi Arabia has reported a remarkable improvement in ambient air quality levels in the Eastern Province of the country where NO2, the marker for traffic emissions, reduced drastically during (12–86%) and after the lockdown (14–81%) periods (Anil and Alagha 2020). Concerning water quality, unfortunately, they may be the likelihood SAR-COV-2 transmissions during collection, treatment, and distribution of water in mega-cities such as in India including other developing countries where sewage treatment facilities are limited (Bhowmick et al. 2020).
On the other hand, the lockdown has led to an improvement in water quality levels of many polluted rivers in many cities by elevating the water quality levels from a poor state to a cleaner form where it can be used for both drinking and other domestic (e.g. bathing) activities due to decrease in pollution levels and sources of these water bodies as a result of the COVID-19 pandemic (Selvam et al. 2020). For example, the lockdown has reduced waste pollution across beaches, resuscitated the coastal ecosystems including improvement in human activities such as noise pollution levels due to a reduction in beach-related business activities (Yunus et al. 2020). It is widely known that COVID-19 pandemic has affected the aviation industry due to the closure of several airports across the world. This has greatly affected the mobility of many travelers and has also caused an economic loss to thousands of aviation industries. Fortunately, the COVID-19 pandemic measures especially the closure of airports have led to huge reduction in aircraft noise pollution levels among populations living closer to airport areas (Iacus et al. 2020a; Suau-Sanchez et al. 2020). Previous studies showed that noise levels produced by aircraft traffic were associated with increased in acoustic discomforts including annoyance, irritations, anxiety, and sleep disorders (Beutel et al. 2016; Brink et al. 2019; Lechner et al. 2019; Quehl et al. 2017). A cross-sectional study on the impact of aircraft noise exposures involving a total of 400 adult population of 45–70 years of age was carried out in Italy (Carugno et al. 2018). It was reported that annoyance levels among residents (65–76 dBA) living closer to the airports were doubled compared to those individuals (60–65 dBA) in far distant areas. Also, complaints about sleep disorders were found to be 36% and 30%, among the residents of areas closer to the airports and far distant areas, respectively (Carugno et al. 2018). A meta-analysis study comprising of more than 16,000 residents found an association with aircraft noise levels and an increase in the incidence of hypertension, especially among women and those with more than 55 years of age following the sub-group analysis (Huang et al. 2015). It was concluded that aircraft noise levels could lead to the prevalence of cardiovascular diseases (Huang et al. 2015). Similarly, there has been evidence of an increase in hospital admissions (Correia et al. 2013) and symptoms of cardiovascular diseases as a result of frequent exposure to high aircraft noise levels (Azuma and Uchiyama 2017). There have been situations of increased in symptoms of heart diseases and the incidence of stroke among people living closer to airports in many European countries following long-term airport noise exposures (Floud et al. 2013).
Over the decades, populations especially those dwelling near airports’ areas were continuously exposed to noise levels with their attendant annoyance and health-related problems (Evrard et al. 2015; Eze et al. 2020; Franssen et al. 2004; Hansell et al. 2013; Lefèvre et al. 2020). Thus, no study has assessed so far aircraft noise levels, annoyance, and health effects over several months during airport closures from the COVID-19 pandemic. Considering the effect of noise on the health and well-being of the exposed population, it is crucial to evaluate the degree of noise exposure levels among resident populations living nearer to airport areas as a result of the impact of COVID-19 lockdowns and social distancing measures. This study aimed to assess aircraft noise exposure levels and the extent of annoyance among residents living closer to Muscat International Airport (MCT), in Oman amid COVID-19 pandemic period. In doing so, both field measurements and online social survey approaches were employed to respectively, estimate noise and annoyance levels among the exposed population. It is believed that these studies could provide background noise data for future noise mitigation measures which could aid in addressing the burden of noise-related health problems. Furthermore, the study outcomes could be used as a proxy in understanding aircraft noise pollution and annoyance levels in other countries across the globe during the current COVID-19 pandemic period.