More than 20,000 lives a year could be saved if major industrial regions cut their emissions of ozone-triggering gases by a fifth, according to a new study published in Environmental Science and Technology.

Ozone is both good and bad. The ozone layer, high up in the atmosphere, is vital for our continued survival because it shields us from harmful levels of UV radiation.

At ground level it’s a different story. Formed when sunlight reacts with emissions from cars, power plants and other sources, it has been linked to cardiorespiratory disease and neoplasia.

Ozone produced by the action of sunlight on air pollution cases cancer, heart disease and asthma.

The researchers found that almost 22,000 ozone-related deaths a year could be avoided (in the northern hemisphere alone), by reducing the pollutant gases (like methane and nitrous oxides) that are the substrates for ozone production.

The most interesting finding, though, was just how far ozone traveled after it was formed. As an example, three-quarters of the lives that could be saved by North American emission cuts were on other continents (especially Europe) – ozone formed on the US east coast was carried to Europe on prevailing winds.

Other regions, though, are poisoning themselves – 90% of South Asia’s ozone victims were local. As a result, the authors estimated that a 20% cut in ozone-precursor emissions would save 7600 lives there annually.

Reducing vehicle-related pollution (and thereby controlling ozone at its source) also helps to slow down climate change: Not only would less fossil fuel be burnt as a result, but ozone and its precursors are also greenhouse gases.

Annual avoided nonaccidental mortalities (hundreds) in each region from 20% NOx, NMVOC, and CO emission reductions in the same region.

Other important findings included:

• Regardless of where emission reductions occur, avoided mortalities are concentrated in highly populated areas (e.g., Northern India and China).
• The greatest rates of avoided mortalities generally occur near the source region.
• Reducing domestic emissions is more effective at decreasing mortalities than reducing emissions in any of the three foreign regions.

Click here to read more about ozone pollution and human health at the Clean Air Trust (highly recommended).