Air Quality

Introduction

Clouds in a summer sky

Courtesy of the EPA

Clouds in a summer sky
Courtesy of the EPA

Clouds in a summer sky

Courtesy of the EPA

Enlarge image

Wherever we are we must breathe the air that surrounds us – we don’t have a choice – and so the quality of that air is important for our health and wellbeing. Air is composed mostly of Nitrogen [N] (78.09%), Oxygen [O₂] (20.95%), Argon [Ar] (0.93%) and Carbon Dioxide [CO₂] (0.04%), but small amounts of pollutants can cause environmental harm and can endanger our health. This is because each of us inhales 20,000 litres of air each day (14 litres every minute) and, with strenuous physical exercise, this increases to 50 litres per minute.

The main air pollutants of concern are

• Oxides of sulphur – from the burning of fossil fuels
• Oxides of nitrogen – from high temperature burning of air in engines and power stations
• Particulate matter (PM₁₀ and  PM_2.5) - from the burning of coal and oil
• Polycyclic Aromatic Hydrocarbons (PAHs) - from soilid fuel burning
• Benzene - from burning petrol in engines
• Carbon monoxide - from motor vehicles
• Ozone at ground level - formed by the action of sunlight on other air pollutants.

These pollutants, alone or in combination, can cause a range of illnesses and even death. They therefore need to be carefully monitored to ensure that levels remain within safe limits.