Petrol-fuelled lawnmowers and household painting put on hold as ozone levels rise over France.

Arthur Rogers/Strasbourg, France

Rising ozone pollution in France has provided an excuse to avoid the chores of gardening and household maintenance.

Under restrictions triggered when ground levels of ozone (O3) - an indicator of photochemical smog - exceed set thresholds, French officials are empowered to ban certain activities in order to reduce emissions of volatile organic compounds. It’s all part of the country’s ozone plan. Activities that may be banned include household painting and, conveniently for some, garden use of petrol-powered equipment.

Ground levels of ozone are created when nitrogen oxides react with volatile organic compounds (VOCs) in sunlight. Ground level ozone is hazardous to human health and the environment. It can irritate the lungs and cause inflammation and breathing difficulties; and it can damage the leaves of plants and reduce crop yields.

Christian Fr?mont, a chief administrative official, or prefect, of the Bouches-du-Rhone department in the south of Francewas first off the mark as temperatures in the Rhone delta soared to 37?C and beyond. Ozone levels exceeded the threshold of 240 micrograms/m3 of air, activating ’le plan ozone’. Pollution peaked at 288 micrograms/m3.

Fr?mont was unavailable for comment when Chemistry World tried to check whether his gendarmes had recorded any incidents of illicit lawnmowing or nefarious use of solvent-based topcoat. 

Equally, the small print of Fr?mont’s decree indicating that it would be OK to resume lawnmowing/painting after 9pm indicates attention to detail, but a certain unworldliness as to how the French spend their evenings, especially when Les Bleus were on a roll during the football World Cup (brought to a sorry end last night).

The restrictions imposed in Bouches-du-Rhone and four other departments are based on EU legislation that prescribes steps starting at an O3 level of 180 micrograms/m3, the ’information level’, when warnings of possible respiratory irritation must be issued.

Interdictions at the ’alert’ level of 240 micrograms/m3 are flanked by powers to impose traffic speed restrictions. At even higher levels, traffic movements and industrial activity can be suspended.

After Europe’s 2003 heatwave, the European Environment Agency warned that further ’very long lasting and geographically extensive episodes’ of high concentrations of harmful ground-level ozone could be expected until EU measures succeed in curbing emission of VOCs and other pollutants ’towards the year 2010’.

The EEA reported that EU emissions of the main precursors - nitrogen oxides and non-methane volatile organic compounds (NMVOCs) - fell by around 30 per cent in the 1990s, and predicted that EU measures should deliver a further 30 per cent reduction.

VOCs are emitted not only by fuels and paints but by thousands of products including lacquers, paint strippers, pesticides, building materials and furnishings. And anthropogenic VOCs make up only one part of the whole VOC picture. ’The natural emission of VOCs from vegetation also increases in warmer weather,’ warned Alastair Lewis, a specialist in atmospheric chemistry at York University, UK.

The combination of these VOCs with nitrogen oxides from fossil fuel combustion contributes to the peaks seen in ground level O3, said Lewis. He has serious reservations about the focus in EU law on anthropogenic NMVOCs.

’The relative contributions of natural to anthropogenic NMVOCs vary widely depending on factors like location, temperature and time of day,’ Lewis told Chemistry World. ’Using control of VOCs - whatever their source - to limit ozone can sometimes have only limited effects, however, since O3 production is a highly non-linear process. Removing one VOC molecule does not necessarily result in one less O3  molecule, and in many environments it is NOx that is the better target to control.’

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