Air quality

Air quality is the state of the air we breathe, assessed according to the concentration of pollutants in the atmosphere. The lower those concentrations, the better the air quality and the lower the risk to health and ecosystems. It is a key indicator of environmental impact in cities and industrial areas.

Assessing air quality requires measuring pollutants such as particulate matter (PM10 and PM2.5), nitrogen dioxide (NO2), ground-level ozone (O3) and sulphur dioxide (SO2), among others. Many of these substances come from the same sources that emit greenhouse gases, so clean air and climate policies often go together.

Air quality indices

To communicate the state of the air clearly, air quality indices (AQI) translate measured concentrations into understandable categories. In Spain, the MITECO Air Quality Index classifies stations into six categories, from "good" to "extremely unfavourable", assigning each station the worst category among the pollutants considered. It is a useful tool both for the public and for companies that want to put their surroundings in context.

Two related concepts are worth separating. Air pollution describes the presence of harmful substances in the air, while air quality is the assessment of the resulting state: the same level of emissions can translate into better or worse air quality depending on the weather, dispersion and local terrain. That is why indices are updated continuously and are often accompanied by short-term forecasts.

Limit values and reference guidelines

Air quality is assessed against reference values. In the European Union, Directive (EU) 2024/2881 of 23 October 2024 on ambient air quality and cleaner air for Europe sets legally binding limit values for 2030, stricter than the previous ones and closer to the World Health Organization (WHO) guidelines updated in 2021.

The two types of reference should not be confused. The directive's limit values are legally binding on member states, while the WHO guidelines are health-based recommendations, stricter than the legal limits, that guide public policy and successive revisions of the rules. Before quoting a specific figure, check the value currently in force in the official text of the directive or in the WHO guidelines, since they vary by pollutant and averaging period.

Monitoring and measurement networks

Measurement relies on networks of monitoring stations that continuously record pollutant concentrations. These stations are usually classified according to the predominant source, into traffic, industrial and background stations, and their data feed indices, official reports and forecasting models. Rigorous monitoring is the foundation of any evidence-based improvement policy.

Using these data, authorities design air quality plans and structural measures such as promoting public transport, electrifying fleets or limiting the most polluting traffic in city centres. The effectiveness of these measures is assessed precisely by comparing how indices and measured concentrations evolve before and after they are applied.

Why it matters to companies

Air quality is relevant to organisations for several reasons: it shapes their licence to operate, affects the health of workers and communities, and is increasingly part of sustainability reporting obligations. Reducing the emissions that degrade the air usually coincides with improving energy efficiency and moving towards sustainable transport, delivering environmental and economic benefits at once.

How Manglai can help

Manglai supports companies in measuring and reducing their environmental impact, integrating emissions management into a solid sustainability strategy. With Manglai's carbon footprint software you can take the first step and measure your emissions rigorously.