How air pollution affects health

Cardiovascular, respiratory, and cognitive impacts — the WHO 2021 evidence summary translated for a general audience.

The headline figure

The European Environment Agency, applying the WHO 2021 concentration-response functions to its population-weighted exposure estimates, attributes approximately 380,000 premature deaths per year to PM2.5 exposure across the EU+UK region; about 50,000 to NO2; and roughly 22,000 to ground-level ozone. These are not double-counted — they reflect partly independent biological pathways and partly overlapping cardiopulmonary endpoints.

Cardiovascular system

The strongest evidence base for PM2.5 mortality runs through the cardiovascular system, not the respiratory system. PM2.5 particles that translocate from the lungs into the bloodstream promote endothelial dysfunction, accelerate atherosclerosis, increase blood-clotting tendency, and trigger autonomic nervous system effects that raise blood pressure and heart rate variability. The dominant attributable causes of death are ischemic heart disease, stroke, and hypertensive heart disease.

Respiratory system

NO2 inflames the airway epithelium and increases susceptibility to respiratory infection. The WHO 2021 review concluded that there is sufficient evidence to support a causal link between long-term NO2 exposure and new-onset asthma in children. PM2.5 and PM10 are major triggers of asthma exacerbation and chronic obstructive pulmonary disease (COPD) hospitalization. Ozone reduces lung function across the population during summer pollution episodes and disproportionately affects outdoor workers and athletes.

Lung cancer

The International Agency for Research on Cancer (IARC) classified outdoor air pollution and particulate matter in outdoor air pollution as Group 1 human carcinogens in 2013. The mechanism involves oxidative DNA damage from polycyclic aromatic hydrocarbons and metal-bound species adsorbed onto PM surfaces.

Neurological and cognitive effects

An emerging evidence base, summarized in the 2021 WHO review, links long-term PM2.5 exposure to faster cognitive decline in older adults and to elevated dementia incidence. The proposed mechanism is inflammatory damage to cerebral microvasculature combined with direct olfactory-pathway transport of ultrafine particles into the brain. This evidence base is newer than the cardiopulmonary literature; the attributable burden is not yet quantified in the EEA mortality estimates.

Pregnancy and child development

Prenatal PM2.5 exposure is associated with lower birth weight, preterm birth, and slowed lung development in early childhood. Children growing up in high-NO2 areas show attenuated lung function growth — a deficit that persists into adulthood. These pathways particularly affect low-income communities and people living near major roads.

Vulnerable groups

The WHO 2021 review identifies five groups with disproportionately elevated risk at any given exposure level: pregnant women; infants and young children; older adults; people with pre-existing cardiovascular or respiratory disease; and outdoor workers (construction, agriculture, traffic). Living within 100 metres of a major road is associated with ~25% higher mortality from cardiopulmonary causes than living 500+ metres away, after adjusting for other socioeconomic factors.

The takeaway

Air pollution is the largest environmental health risk in Europe. The EEA estimates each 1 µg/m³ reduction in population-weighted PM2.5 prevents around 38,000 premature deaths per year across the EU+UK. This is why the gap between EU limits and WHO guidelines matters: closing it is not symbolic — it is a public-health intervention.

Source: European Environment Agency Air Quality e-Reporting Database, Dataflow E1a (validated annual).

Source: World Health Organization Global Air Quality Guidelines (2021 update).

Sources: European Environment Agency Air Quality e-Reporting; WHO Global Air Quality Guidelines 2021; EU Directive 2008/50/EC and the revised Directive (EU) 2024/2881; Copernicus Atmosphere Monitoring Service.