Here is one hurdle for a business to achieve sustainability: answering questionnaires.

It's about data collection, and a growing number of companies large and small are not just analyzing their own carbon footprint, but also the emissions of their suppliers and customers.

A new GTM Research report scheduled for publication at the end of the month shows that 70 percent of the companies surveyed have already set pollution and waste reduction goals. Forty-six percent of them already take part in emissions labeling programs for their products while 36 percent of them plan to do so in the coming year or two.

But the costs and efforts for this undertaking can be particularly daunting for small and mid-size businesses.

Earlier this year, Walmart said it would begin asking its more than 100,000 suppliers to track and report the emissions from their manufacturing processes, water use, and waste production, among a host of other issues.

PepsiCo, meanwhile, has seen more of its suppliers answering its supply chain questionnaire. The beverage and food giant received replies from 57 percent of its suppliers in 2008. That rate jumped to 90 percent with the most recent request for answers, said David Walker, director of environmental sustainability for PepsiCo, at Greentech Media's Greening the Supply Chain conference in Boston Thursday.

"Any company that turned in the questionnaire has a climate change strategy. Now we can begin to talk to each other about shared values," Walker said.

Taking a comprehensive look at emissions – let alone coming up with ways to reduce pollution – can pose special challenges for businesses without the resources of a PepsiCo or Walmart. Certainly, some companies are finding it difficult to hire someone who is knowledgeable about coordinating emission reduction efforts.

"If you are a smaller organization, having a person with that level of expertise can be a challenge, especially when you go to fill out the questionnaires," said James Salo, vice president of strategy and research of TruCost, a London-based consultancy that works with companies on collecting and analyzing their emissions.

Information about the costs of carrying out these emission tracking and reduction efforts also can be hard to come by in public discussions. Companies are happy to discuss their use of renewable energy and recyclable packaging materials, but they don't like to talk about the costs.

Walker declined to say how much PepsiCo, which does business in all but four countries in the world, spends on all of its sustainability efforts. He did share that the 1 percent to 2 percent of the company's capital expenditure goes toward emission-cutting projects such as renewable energy generation and water and waste treatment.

In between sessions at the conference, Paul Baier, vice president of consulting at Salem, Mass.-based Groom Energy Solutions, said a company with an annual revenue of $500 million or more could expect to spend anywhere between $50,000 to $150,000 for assembling a report analyzing its own carbon footprint.