The emission of primary particles, smaller than 10 µm (PM₁₀), particles smaller than 2.5 µm (PM_2.5) and all total suspended particles (TSP) have decreased in the period 2000 – 2021 in Slovenia by 21 %, 29 % and 20 %. The main source of emissions of particulate matter are households, mainly due to use of biomass for domestic heating.

In 2021, the levels of benzo(a)pyrene at all urban monitoring sites reached the target value. Annual trends of benzo(a)pyrene levels show that the highest levels are measured during the heating season. In summer, levels are significantly lower at all locations.

Air pollution is the most important environmental risk factor for human health, affecting an average of 400,000 premature deaths in the EU and costing Europeans an average of more than € 166 billion a year. In the case of the cities of Ljubljana and Maribor, external costs amount to almost EUR 271 million annually. Estimation of external costs of air pollution from transport is slightly decreasing.

Plans to improve air quality in Slovenia include a number of measures. It is crucial that the state ensures the financing of measures and thus the implementation of measures, and consequently the improvement of ambient air quality. In 2019, as much as EUR 15.56 million more investments were paid out than in 2014. In the period from 2014 to 2019, most investments were in wood biomass boilers, followed by investments in heat pumps.

Trends in annual precipitation are not as obvious as temperature trends. Changes between years and differences between regions are significant. According to climate change projections, annual precipitation will slightly increase while changes in seasonal precipitation will be noticeable. The most worrying are summer conditions, because less precipitation and higher temperature might result in higher frequency of droughts. In winter, more precipitation may lead to an increase in flooding events.

Precipitation is highly variable in space and time, even more than temperature (storms and hail). In the last two decades, Slovenia is observing catastrophic droughts and abundant precipitation resulting in floods, sometimes drought and floods occur even within the same year. The maximum snow cover depth and the depth of fresh snow decreased in the period 1961-2022.

The decrease in SO₂ emissions from transport is significantly influenced by the tightening of legislation governing the concentration of sulphur in liquid fuels (since 2009, it has been limited to 10 mg/kg for both petrol and diesel). The limit value of concentration of sulphur in fuels used in road transport in 2015 was not exceeded in Slovenia or in the EU-28; the same applies to air and maritime transport.

According to the state of epiphytic lichens, the preservation of forests and air quality is poor in the entire territory of the Republic of Slovenia, except in forests at higher altitude in the Alps and partially in the Dinaric mountain range.

In recent years, cadmium and lead concentrations in the kidneys and livers of roe deer has decreased below the level of toxic concentrations that could have a direct adverse effect on the health of the individuals of this species. Nevertheless, cadmium concentrations in the internal organs of roe deer exceed the admissible concentration determined by law in many areas of Slovenia (taking into consideration the suitability for human consumption).

In the period 2002-2021, the highest exposure to ozone concentrations were detected in the Primorska region in summer where air quality measuring stations in Koper and Nova Gorica detected highest ozone concentrations in ambient air. There are some differences from year to year in a level of ozone exposure due to meteorological conditions in the warm half of the year and other regional characteristics.