00:00Lance Roule is director of the Copernicus Atmospheric Monitoring Service, also known as CAMS.
00:07Welcome to the program. Just 5% of the world's population has been exposed to good ozone levels this year.
00:14What constitutes good according to the present guideline? What does that mean?
00:22Yeah, what is good is defined, as you said, by the World Health Organization.
00:29In fact, the World Health Organization publish regularly guidelines that elaborate on the basis of relationships between exposure to air
00:39pollutants and disease, mortality, statistics.
00:44And good means that we are below the levels that are set by the guidelines, by the World Health Organization
00:53regarding exposure to ozone, exposure, short-term exposure, so I mean during every day, during peaks, or longer-term exposure,
01:03I mean during season.
01:05So good means that they are below those guidelines, so it's by W2.
01:09And where do those lucky 5% find themselves in the world? Tell us where they are geographically.
01:17What you can see in the report is that, in fact, the southern hemisphere has a lower level of ozone.
01:25And this is simply because there is a strong seasonality in ozone exposure.
01:30Ozone is built upon the emissions of some precursors, and those reactions are triggered by sunlight and heat, which means
01:41that for the period that we have investigated, the first 6-8 months of the year, the northern hemisphere was
01:49most exposed.
01:50So the 5% are mainly in the southern hemisphere, and in some parts of the northern hemisphere, like the
01:57Tibetan plateau, which is not exposed, but not so many people there.
02:01The analysis identifies Asia as the region most impacted by ozone pollution globally. Why is that?
02:09So this is a combination of many factors. First, emissions, emissions of precursors, because once again, tropospheric ozone is a
02:18secondary pollutant, so traffic, industry, very, very dense city, megacities, those are all sources of ozone precursors.
02:28And specific meteorology with, as I said, sunlight, high temperatures, and also in some parts of the continent, specific geographical
02:40conditions, like this plain in the north of India, where the pollution stays stuck, in fact.
02:51So this is a combination of several factors.
02:53We've spent all summer seemingly reporting on heatwaves and wildfires. I wonder how much they have contributed to this.
03:03Heatwaves can trigger definitely the occurrence, the development of ozone episodes and high ozone concentrations in the lowest part of
03:16the atmosphere.
03:17So this is an important factor. This is a driving factor. Regarding Wi-Fi, they emit a large amount of
03:25precursors, like nitrogen dioxide or volatile organic compounds.
03:31And in doing that, they participate in the formation of ozone, because they emit those precursors.
03:37Laurence Gruuil, the director of the Compernicus Atmosphere Monitoring Service. Thank you very much indeed.
