Here's a short story:

ISO 20121 (full name: ISO 20121:2012, "Event sustainability management systems –- Requirements with guidance for use") is a voluntary international standard for sustainable event management, created by the International Organization for Standardization. The standard aims to help organizations improve sustainability throughout the entire event management cycle. 

Every event – from a village barbecue to a major sporting event like the Olympics – will have economic, social and environmental impacts. Water and energy resources are put under pressure, significant amounts of waste and carbon emissions can be generated. Sometimes events can put a strain on local communities. By 2005, practitioners within the events industry were becoming aware of the need for more sustainable practices. 

Specifically, the Head of Sustainability at the London 2012 Olympic and Paralympic Games, David Stubbs, was looking for a way to make good on the sustainability promises made in the London Games bid. 

He raised the issue with the British Standards Institution (BSI) in the UK. This led to the creation of BS 8901:2007 "Specification for a sustainable event management system with guidance for use". After a period of review, the second version of BS 8901 was published in 2009. 

BS 8901 was received very positively by the international event industry, and was soon being widely used. For example, COP15, the United Nations Conference on Climate Change, was certified as compliant with BS 8901 in December 2009. The Microsoft Corporation achieved certification to BS 8901 at its Microsoft Convergence® 2009 event in New Orleans, Louisiana, in March 2009. (End of story)

Provide your best guess for the following question. Give ONLY the guess, no other words or explanation.

For example:

Guess: <most likely guess, as short as possible; not a complete sentence, just the guess!>

Here are a few examples of questions and answers:

Question: What is the article mainly about?
Guess: Event sustainability

Question: What is one example of an event that comes with impacts?
Guess: a village barbecue

Question: Name another?
Guess: the Olympics

Question: And the last?
Guess: a major sporting event

Question: How many types of impacts are there?
Guess: Three

Question: Name one?
Guess: economic

Question: Can the environment be impacted?
Guess: yes

Question: What other impact haven't we mentioned?
Guess: social

Question: What is one type of resources can be strained?
Guess: water

Question: What's another?
Guess: energy

Now answer the following question in the same format.

Question: What is one type of emission this can generate?

waste