Control of ozone in cities is beyond the power of local regulators

The most critical factor affecting ozone concentrations in cities is the amount drifting in from outside their boundaries, which means that it is beyond the control of local regulators, according to new research.

The study from Ohio State University in the United States, which examined ozone pollution in over 300 cities, indicated that public transport, forests and farmland in cities can have a positive impact on lowering levels of ozone. A 1% increase in public transportation was found to decrease ozone by 0.51%, and an equal increase in forested land in the city decreased ozone by 0.019%.

The study also investigated carbon monoxide levels in over 100 cities, and found that the quantity of the pollutant was predominantly determined by the number and placement of road intersections within each conurbation.

“Researchers already know most of the causes of air pollution in our cities, but the advantage of our statistical analysis is that we can measure the relative importance of each of these causes,” said Jean-Michel Guldmann, co-author of the study and Professor of City and Regional Planning at the University. “Our results confirm that ozone is transported over long distances with minimal decay. Local efforts are not going to control ozone in a city – there has to be a comprehensive national policy, which is consistent with what the [Environmental Protection Agency] has been doing.”

A further major factor influencing ozone levels was found to be building construction, with every 1% increase in construction accompanied by a 0.69% rise in ozone levels. According to Guldmann, construction involves a lot of truck traffic and use of paints and chemicals which can help boost ozone levels.

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