No abstract

Air is a very important part of the environment, which also affects other elements. It has implications for living conditions, the condition of ecosystems, and the processes of climate change. The greatest impact of air pollutants on human and animal health are observed in industrial and urban areas [1]. One of the negative phenomena that increasingly occurs in cities is smog. Classic smog occurs in the winter months. It is caused by low air temperature, which results in higher heating of apartments, especially by people who use low-quality fuel for this purpose. In addition, among other things, due to adverse meteorological conditions (e.g., lack of wind and precipitation), temperature inversion occurs at this time. Photochemical smog occurs in warm months, when the air temperature is about 25-35°C and is windless. Its main causes are reactions that occur between the oxides of nitrogen and hydrocarbons from car exhaust and light [2]. As a consequence, harmful compounds are formed. The composition of smog includes, among other things, dusts. It may include hydrocarbons, elemental carbon, silicon compounds, aluminum, iron, trace metals, sulfates, nitrates, chlorides, and ammonium compounds. Dusts in the air are associated with direct emissions, in particular from transport and from municipal sources, but also due to the reaction between substances contained in the air. The most commonly measured particle size indicators are PM 10-particles with a diameter fraction of less than 10 μm, and PM 2.5-particles with a diameter fraction less than 2.5 μm [1].

The coronavirus disease (COVID-19) has caused huge changes in people’s daily habits and had a significant impact on the economy. The lockdowns significantly reduced road traffic and meant that many people worked remotely. Therefore, the question arose as to how the reduced road traffic and stays of residents at home affected the degree of pollution and the structure of major air pollutants. To answer this question, the article presents an analysis of changes in typical air pollutants (PM10, PM2.5, NO2) in the five largest Polish cities and one of the voivodships. The data from the Polish State Environmental Monitoring were used for the analysis. The analysis showed that the period of the first lockdown in Poland (April 2020), despite the reduced road traffic, resulted in a significant increase in PM10 emissions (9–91% during working days and an average of 30% on Saturdays and Sundays), a slight increase in PM2.5 emissions (on average from 2% to 11% for all analyzed locations), and a reduction in NO2 emissions (on average from 6% to 11% for all analyzed locations) compared to the period before the lockdown. However, the changes were not homogeneous—in Łódź and Warsaw, in most cases, an increase in all analyzed pollutants was observed, and the greatest decrease in pollution took place in Małopolska voivodship (including Kraków). Comparing the data from April 2020 to the data from April 2019, the overall difference in the PMs concentrations was small, although there are places where there has been a significant decrease (Wrocław, Poznań), and there were also places where the concentration increased (Warsaw, Łódź, Małopolska). In the case of nitrogen dioxide, pollution concentration decreased in most locations. The only exception was the background stations in Warsaw, where the increase was 27%.

This article presents a long-term evaluation of low-cost particulate matter (PM) sensors in a field measurements campaign. Evaluation was performed in two phases. During the first five months of the campaign, two PM sensors were simultaneously compared with the results from the reference air quality monitoring station in various atmospheric conditions—from the days with freezing cold (minimum temperature below −10 °C) and high relative humidity (up to 95%) to the days with the maximum temperature above 30 °C and low relative humidity (at the level of 25%). Based on the PM10 measurements, the correlation coefficients for both devices in relation to the reference station were determined (r = 0.91 and r = 0.94, respectively), as well as the impact of temperature and relative humidity on measurements from the low-cost sensors in relation to the reference values. The correction function was formulated based on this large set of low-cost PM10 measurements and referential values. The effectiveness of the corrective function was verified during the second measurement campaign carried out in the city of Nowy Sącz (located in southern Poland) for the same five months in the following year. The absolute values of the long-term percentage errors obtained after adjustment were reduced to a maximum of about 20%, and the average percentage errors were usually around 10%.

The aim of the study was to determine air pollution over the sea surface (North Sea and Baltic Sea) compared to the situation in ports, as well as to examine the impact of ships on the level of particulate matter (PM) concentration. The measurements, made during the two-week cruise of the tall ship Fryderyk Chopin, demonstrated that the principal source of PM emission over the sea surface are passing ships equipped with internal combustion engines, including quite numerous units powered by marine oil. The highest pollution levels were observed in locations distant from the coast, with increasing concentrations when other ships were approaching. During the cruise, at least two places were identified with increased PM concentration (18–28 μg/m3 for PM10 and 15–25 μg/m3 for PM2.5) caused by passing ships. The share of PM2.5 fraction in the general PM concentration in these places increased from 70–72% to 82–85%, which means that combustion emission dominated. In turn, measurements made in ports (Copenhagen and Kołobrzeg) showed lower levels of air pollution and indicated a typical variability of the PM concentrations characteristic for land areas. The results confirm the need for determining suitable solutions for sustainable sea transport.