Global ozone pollution warning

Current controls are failing to protect human health and the environment from increasing ground-level ozone, according to a report by the Royal Society. The report says international action is needed to curb the pollutant and protect people and crops.

Although ozone (O₃) in the upper atmosphere shields the Earth from harmful ultraviolet rays, ozone close to the ground is an increasingly serious problem as it is a potent oxidant and contributes to photochemical smog. During hot summer months ozone levels can spike, exacerbating conditions like asthma in vulnerable people. It is also thought to interfere with photosynthesis and has been shown to stunt the growth of some crops.

Over 1500 deaths in the UK during 2003 were attributed to ozone - a figure that is expected to rise by more than 50 per cent in the next 20 years. Children, asthmatics and the elderly are particularly vulnerable to the pollutant, which can irritate the lining of the nose and lungs. In addition, reductions in the yields of crops like wheat, rice and soybeans caused an estimated loss of 6.7 billion euros in the EU alone during 2000. 

’This is a truly global problem, as ozone produced in one country can migrate to others through weather systems and jet streams,’ says David Fowler, the chair of the Royal Society’s ground-level ozone working group. ’A global strategy is needed to deliver the kind of reductions that are necessary to protect human health and the environment.’

Ozone is not emitted directly from any source, but instead is made by photochemical reactions from volatile organic compounds and nitrogen oxides released from fossil fuel burning - primarily from vehicle exhaust fumes. Although some countries have had great success in reducing ozone levels through the widespread adoption of catalytic converters on road vehicles, global emissions of ozone precursors are still increasing and its effects are expected to worsen. 

’Polluted air can travel thousands of miles,’ says Mike Pilling, an expert in atmospheric chemistry at the University of Leeds. ’So here in the UK for example, when the wind comes from the east we import a great deal of ozone precursors from Europe.’

Increasing ground-level ozone is also closely linked to global warming, Pilling warns, as ozone is a powerful greenhouse gas. Additionally, the changing climate will mean that ozone concentrations will increase in heavily polluted areas of the world, indicating that the pollutant could threaten agriculture in developing countries. 

’Europe, the US, and certain countries such as China have already committed to very substantial ozone controls,’ Pilling says. ’But it is critical that legislation is implemented across the globe to combat this problem.’

Lewis Brindley