Fine particulate matter (PM2.5) and other pollutants (PM10, ozone, nitrogen dioxide) can affect health over short and long periods. According to WHO and EPA assessments, exposure is linked to cardiovascular and respiratory effects, including reduced lung function, asthma exacerbations, and increased risk of heart attacks and strokes. Vulnerable groups include people with heart or lung disease, older adults, and children. WHO publishes global air quality guidelines for these pollutants.