Air pollution is the presence of certain particles in the air (including gases, solid particles and liquid droplets) that have detrimental effects on human health and the environment. The main air pollutants typically measured when determining the quality of the air include particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and ozone (O3). Regulating and limiting the concentration of these pollutants in the air is crucial for protecting our health.

Several regulations (laws) and recommendations (guidelines) are in place in order to protect citizens and natural ecosystems. These set an upper acceptable limit for both long-term (annual) and short-term (e.g. 24-hour) exposure to air pollutants.

In Europe, some of the most comprehensive regulations on air quality have been established. The Directive 2008/50/EC is a significant piece of legislation established in 2008, which sets specific limits for the concentration of different pollutants found in ambient (outdoor) air. A revision of this directive is expected in 2024, taking into account the latest scientific evidence on the health impacts of pollutants, and setting stricter air quality standards to be met by 2030.

Countries in the EU have the legal obligation to keep pollutant concentrations below the set limits, and can face substantial fines when they fail to meet these standards. The air pollutant levels are typically tracked by fixed monitoring stations, and reported to the government and public. Certain measures are implemented to ensure compliance with the air quality standards, such as establishing a low emission zone in cities with a large population, like London and Berlin. In addition, countries can set their own limits that can be even more restrictive than those established by the European Union.

Besides legally-binding directives, different organisations release recommendations and guidelines that can help countries define their air quality goals and policies. Notably, the World Health Organization (WHO) guidelines, last updated in 2021 with the next update expected in 2030, define safe exposure levels for pollutants based on the latest research and evidence, and are considered key in guiding policies and strategies for tackling air pollution.

Overall, regulations and efforts to decrease pollutant levels are expected to continue evolving with new research, ultimately aiming for cleaner air in Europe and mitigating the health impacts of air pollution.