Air quality monitoring in the eastern Jiul Valley

. Jiu Valley is an area with a tradition in the field of mining. Over time, coal mining has been the main driver of the local economy. The decrease in the level of coal use also led to the closure of mining units in the Jiu Valley. Such transitional actions require calibration to climate, environmental and health responsibilities. Air pollution specific to the area has, perhaps, the most significant impact on the quality of population’s life in terms of affecting health. The paper presents the air quality monitoring in the Eastern Jiu Valley for a period of four months (one sampling campaign/month), between February and May 2023, in six monitoring points, with the help of the Mobile Environmental Laboratory which has the facility of simultaneously determining several samples for quick identification of polluted areas. The established monitoring program includes the monitoring points, monitoring frequency and duration, as well as the areas where the mobile laboratory was located. The analysed data highlight the air quality in the Eastern Jiu Valley to establish the medium and long-term objectives in each area where the mobile laboratory was located, as well as the level of exposure of resident population. The concentration levels found in different urban areas illustrate the average concentrations of dust, gases and ozone caused by both activities in the area and road traffic.


Introduction
Clean air in cities improves our health and overall quality of life and helps fight climate change and preserve the environment.High-resolution measures of pollutant concentrations can support the identification of urban areas with poor air quality and increase citizen awareness while encouraging more sustainable behaviours.
Recent advances in Internet of Things technology have led to the widespread use of low-cost air quality sensors for hyper-local air quality monitoring.As a result, public administrations and citizens increasingly rely on information obtained from sensors to make decisions in everyday life and to mitigate the effects of pollution.
Over the last years, the mining sector has been exposed to rapid changes, namely layoffs and restructuring of the mining industry.The restructuring process continues today, in line with developments related to the coal transition at European level, with the prospect of closing the 4 mines (Lonea Mine and Lupeni Mine in the middle of the closure program, respectively Livezeni Mine and Vulcan Mine, closure conditioned by the measures the Romanian state will implement).The extractive activity in the Jiu Valley was one of the main sources of pollution, causing degradation of some environmental components and an ecological imbalance with an impact on the life of living organisms.The prospect of closing the remaining operational mines raises serious concerns both from the perspective of the subsequent exploitation of these sites of a manner that does not affect the environment, as well as their reinsertion into the natural and/or economic circuit, without negatively impacting the health of inhabitants and the environment, inclusively by rethinking the greening methods.
Reducing the negative effects on biodiversity, which provides services that support economic prosperity and quality of life, and adopting measures to protect and, as the case may be, rehabilitate ecosystems affected by human activities are priorities from the perspective of environmental protection assumed by the "Economic, social and environmental development strategy of the Jiu Valley" (2022-2030).Consequently, the current economic profile of the Jiu Valley is dominated by the service sector -especially trade, over 40% of the total number of companies active in the private sector in the Jiu Valley operating in this sector.
The choice of monitoring air quality in the Eastern part of the Jiu Valley was made because the Western part, more precisely the city of Vulcan, already has an air pollution measurement station, and the "Economic, social and environmental development strategy of the Jiu Valley" (2022 -2030) mentions that a pilot program for environmental quality monitoring will be implemented to ensure coverage of monitoring needs in all 6 jurisdictions.
The aim of the paper is to evaluate the impact of current economic activities on the environment and implicitly on the health of population caused by immissions of dust and gases in the Eastern part of the Jiu Valley.The analysed data highlight the air quality in the Eastern part of the Jiu Valley to establish the medium and long-term objectives in each area where the mobile laboratory was located, as well as the level of exposure of resident population.
On one hand, the research explored aspects of air quality using the mobile laboratory provided by the NIRD INSEMEX Petrosani, equipped with instruments for measuring: carbon monoxide (CO), sulphur dioxide (SO2), nitrogen oxides (NO 2 , NO, NOx), ozone (O 3 ), hydrogen sulphide (H 2 S) and dust in suspension, and on the other hand the impact of pollutants on resident population

Materials and methods
The research is primarily based on data from health-related air pollutant monitoring and focuses on six indicators of air pollution: • PM, measured as particles with an aerodynamic diameter <10 μm (PM10) and <2.5 μm (PM2.5) • carbon monoxide (CO), • nitrogen dioxide (NO 2 ), • sulphur dioxide (SO 2 ), • hydrogen sulphide (H 2 S), • ozone (O 3 ).These indicators were selected in order to identify typical air pollution concentrations.This selection, however, does not mean that other substances do not pose a considerable threat to human health and the environment at levels present in urban and industrialized areas.Air pollution exists as a complex mixture, and the effects attributed to ozone, nitrogen dioxide, sulphur dioxide or particulate matter (PM) may be influenced by the underlying toxicity of the complete mixture of air pollutants.Processes in the atmosphere further transform these pollutants into new compounds.For example, ground-level ozone is a secondary pollutant produced by the interaction of sunlight with nitrogen dioxide and volatile organic compounds (VOCs).The sources for these substances are different and so are the impacts on human health, which makes air pollution a complex process.
The monitoring of air quality parameters was carried out with the help of the mobile environmental laboratory endowment of NRDI INSEMEX Petrosani infrastructure, equipped with analysers and gas chromatographs that measure suspended dust particles (PM2.5, PM10), carbon monoxide (CO), nitrogen dioxide (NO2) and sulphur dioxide (SO 2 ), hydrogen sulphide and ozone.Measurements are supplemented with information on temperature, humidity and atmospheric pressure, from the station fitted on the vehicle, which has a 6m mast.Air quality monitoring was performed in the Eastern part of Jiu Valley for a period of four months (one sampling campaign/month), between February and May 2023, in six monitoring points.
Atmospheric conditions greatly influence the distribution of chemicals in the atmosphere.For example, humidity and low temperatures cause low concentrations of chemicals in the atmosphere, which are either blown away by wind or washed out of the air by precipitation.High temperatures keep chemicals inside the city and contribute to reaching critical thresholds for human health.
The sampling from surrounding air is carried out by means of a common collector, and the sampling method for the collected sample is carried out by means of individual sampling lines to which gas chromatographs and analysers, endowment of the mobile laboratory, are attached.The main collector consists of a precipitation protection device to prevent precipitations from entering the sampling line.The inlet of the main collector as well as the sampling line are made of polytetrafluoroethylene (PTFE) in order not to influence the sample composition.
The equipment used complies with reference standards and has calibration certificates.Moreover, before starting the sampling campaigns, they are calibrated with the help of the multi-component cylinder provided in the mobile laboratory.All data obtained are recorded by the IOVIS system and then transferred to a laptop.
The monitoring points have been established so that we can cover the Eastern part of the Jiu Valley depending on the activities carried out in the area, the resident population and interference of the main sources of air pollution that can have a harmful influence on human health.In this regard, six monitoring points (MP) were established in the Est part of the Jiu Valley, one of them being considered a blank sample, as follows: -MP1 -behind the University of Petrosani, considered a blank sample, because it is surrounded by fir trees, being out of road traffic; -MP2 -Livezeni Mining Exploitation; -MP3 -NRDI INSEMEX premises, located next to the national road that connects Petrosani to the Parâng Mountains tourist area; -MP4 -INCD INSEMEX testing ground premises, located in an area with households and businesses (wood processing); -MP5 -Petrila City Hall, -MP6 -Lonea Mining Exploitation.The duration of the monitoring program was four months (February -May), with 8 hours/day/month in points MP1, MP2, MP6 (the mobile laboratory positioned in an unguarded area) and 24 hours/month for points MP3, MP4, MP5 (the mobile laboratory positioned in a guarded area).
According to Law no.104/2011 regarding the quality of the surrounding air, the sampling points were located as to avoid measuring the neighbouring microenvironments, so that the values obtained are relevant for the air quality.

Results and discussion
The values measured with the help of the mobile environmental laboratory represent the average of the measurements carried out over a period of 8 hours / 24 hours during the four months, in conditions of a partly cloudy sky, without precipitation.The analysis of the average concentrations obtained (table no.1), shows exceeding of the Maximum Admissible Value (MAL) of the national legislation for: -PM2.5 suspended dust in February at monitoring points MP2, MP3, MP5, with an average atmospheric humidity of 83.31% and an average temperature of 0.91 o C, in March at monitoring point MP2 and in April at monitoring point MP5, with an average atmospheric humidity of 83.38% and an average temperature of 4.89 o C; -suspended dust PM10 in February at monitoring points MP2, MP5, with an average atmospheric humidity of 81.91% and an average temperature of 0.91 o C and in March at monitoring point MP6, with an atmospheric humidity of 87 .1% and an average temperature of 6.33 o C; -nitrogen dioxide in March at monitoring point MP3 with an atmospheric humidity of 91.97% and an average temperature of 12.8 o C, in April at points MP3, MP4 and in May at points MP1, MP3 under the meteorological circumstances specified in table no.1; also, the average value obtained in May at point MP5 is close to the VLA, requiring monitoring over a longer period.
We mention that all monitoring points were chosen outside of road traffic.Exceeding the maximum allowed values is estimated to be caused by the activities carried out in the areas where the mobile laboratory was located, a large proportion being caused by the thermal agent used both at the mining units and in households, considering the rather low temperature in the winter-spring period.
Several case studies [2,3,7] analysed the air quality in Petrosani, each one analysing in particular the impact generated by road traffic on air quality and implicitly on the health of population.The new environmental objectives included in the Economic, Social and Environmental Development Strategy of the Jiu Valley (2022-2030) refer to environmental monitoring in all 6 jurisdictions, which will contribute to a much broader analysis of air quality and population health.
The Even if the other monitored indicators are not yet included in the public reports, considering that the HD-5 station is located in the western part of the Jiu Valley, certain comparisons cannot be made with the values obtained in the eastern part, as distances are quite appreciable.However, we can observe that the maximum concentration obtained by the HD-5 automated station are lower than those obtained in this study, due to the fact that the mobile laboratory was positioned near some possible sources of pollution, for example mining units, households.

Conclusions
The mining industry in Jiu Valley had and still has a significant influence on air quality through the release of harmful substances and on soil quality through tailings storage, as well as by generating industrial waste that can cause negative effects on the health of inhabitants.
As part of the Nucleu Project -PNEXH2, measurements were carried out for four months (winter-spring) regarding atmospheric air quality parameters in the Eastern part of the Jiu Valley in order to be able to evaluate the influence of mining activities (even if it is quite reduced currently) and home heating on atmosphere quality.The results obtained showed that the air is polluted especially with PM10, PM2.5 and nitrogen dioxide.We mention that the concentrations of suspended dust are strongly influenced by seasonal variations.
Based on this assessment, the methods of air quality management can be established by identifying, on a local scale, the areas of interest where integrated air quality plans, air quality maintenance plans and short-term action plans (where no pollution has been found), targeting the health of resident population.
Through modern measures plans, developed and implemented by the Hunedoara County Council along with the local town halls (Petrosani, Petrila), and, last but not least, by complying with national legislation by all possible factors involved, whether we are talking about industry, builders, households, etc. we will be able to establish the most effective ways to reduce pollution.
It is recommended to intensify the monitoring process to improve the control and management of air quality and to get a clearer picture of the main sources of pollution.Also, pollutant dispersion modelling is of real help in establishing the extent of pollution and its degree of intensity in different areas.
Degradation of air quality has been a cause of concern these days and real-time monitoring of air quality helps us keep a check on it.

Fig. 2 .
Fig.2.Measurement locations (measurement points)Centralization of the average values determined from the sets of values obtained on the sampling days, over a period of four months (February, March, April, May) as well as the limit value for protection of human health are shown in table no.1.

Table 1 .
Centralization of the average values determined * Parameters without normative.

Table 2 .
table below compares the values obtained in this research to results of the nearest station of the National Air Quality Monitoring Network (RNMCA), namely the HD-5 monitoring station in Vulcan Municipality located in the western part of the Jiu Valley.On the https://www.calitateaer.rowebsite (table no. 2) only the concentrations of PM10 are presented, respectively: Values obtained from HD-5 monitoring station in Vulcan Municipality *