ESTRO 2024 - Abstract Book

S2941

Interdiscplinary - Other

ESTRO 2024

bigger cities enroute [4] and was validated for 3 example journeys. Published conversion factors [2] were used to calculate the carbon footprint, in units of kg CO 2 equivalent (CO 2 e).

The maximum impact of train travel was estimated by calculating the carbon footprint if all attendees within Europe travelled by train. Other potential scenarios were estimated by replacing Vienna as the host city with other European cities that have held the congress before, will host it or are popular conference destinations. The influence of simultaneous congress hubs on carbon footprint was modelled for different combinations of hubs in Europe (Amsterdam, Berlin, Zurich and Madrid), America (Denver), Asia (Singapore) and Africa (Cape Town). It was assumed that all attendees would travel to the most nearby congress hub. Finally, one scenario with online attendance was modelled by assuming that all non-European attendees would participate online and all European onsite in Amsterdam.

Results:

The total number of attendees at ESTRO23 was 6,710 of which 76% were from Europe, 9.6% from the Americas, 7.5% from Asia/Pacific and 1.1% from Africa. The top 5 countries by number of delegates were UK, Germany, Netherlands, US and Italy, with 606, 593, 565, 427 and 396 respectively. Of the 450 respondents to the post ESTRO23 survey 47 travelled to Vienna by international train. Figure 1 shows the total travel carbon footprint for 12 different venues (black bars) and the equivalent carbon footprint if everyone in Europe travelled by train (green bars). With current modes of transport (black bars) the lowest travel carbon footprint would be if the ESTRO congress was held in Amsterdam with 6,607 tCO 2 e, equivalent to driving 39 million km in an average car. This is 37% lower than holding it in Madrid. If everyone in Europe travelled to Amsterdam by train this would reduce to 5,358 tCO 2 e, a 19% reduction compared to current modes of travel.

Figure 2 shows the modelled scenarios if there were 3 ESTRO hubs within Europe in addition to Amsterdam (blue bar). The addition of 3 European hubs reduces the total travel carbon footprint by 16%. International hubs in addition to Amsterdam (green bars) saves 27%, 49% and 51% adding 1,2 or 3 hubs respectively. The total carbon footprint of holding the congress at Amsterdam is also shown for comparison (red bar). If all non-European delegates were to join an Amsterdam based ESTRO congress online, with European delegates travelling as they currently do, the travel carbon footprint would drop by 80% (orange bar).