We'll always need air quality consultants
Air quality and its cousin integrated pollution prevention & control (IPPC) never top the league when consultants and their clients are asked where they expect to see rapid growth in coming years - but there's always going to be a need for professional advice in this area.
He acknowledged that tackling climate change, waste management and renewable energy - the top three areas flagged up by consultants - were likely to continue to dominate the market for the foreseeable future.
But, he said, while the private car is the preferred form of transport in the UK, there is always going to be plenty for the air specialists to get their teeth into.
"There will always be work for us as long as we're driving these rather filthy armchairs around," he said.
The oft-cited belief that work for air quality specialists is drying up as regulated industry already meets required standards is largely false, he said.
"I guess there's a wrongly held perception that air quality work is all about industrial pollution regimes," he said.
"It always comes as a surprise to the non-specialists that, unless you've got specific local issues, industry's really not the main contributor to the nasty stuff that makes the pages of the newspapers."
The largest source of emissions for all the usual suspects - particulate matter, NOx and sulphur dioxide - is transport.
On the industrial side, said Mr Bollan, the sector has reached something of a plateau in the UK.
"Regulators have made a concerted decision to be more of a friend to industry," he said.
"That's not to say they're going easy on them, but the permitting process has become rather more realistic and proportionate.
"Whereas before year-on-year improvements might have been specified in the permit, it's now recognised that that's not sustainable indefinitely."
He said that, by and large, regulated industrial sites now meet the required standards and the technologies helping them to do this are well-evolved.
"Once everybody's meeting the same standards, the only thing to compete on is price so that's a commodities market now," he said.
Nigel Clark, marketing director of Enviros, agreed that the industrial pollution control market, while not at its peak, was still healthy.
“The main hurdles around pollution treatment and control legislation hit in 2006-07,” he said.
“There’s ongoing work to ensure that people comply with their action plans and stay within the boundaries that they have been set or set themselves but there’s nowhere near the pace of work that there was in 2005-07.
“It is a shrinking concern, but it’s from a very high peak of work. If we went back two or three years, we would probably find that the majority of environmental consultancies were having a bit of a boom time in this area. That level of activity was never going to be sustained.
“It’s going back to a sensible state rather than dropping off a cliff.”
Mr Bollan added that there is still growth in pollution prevention markets beyond the UK - in India, the Middle East and parts of Eastern Europe, for example.
But when it comes to transport, there's still a lot to be done in Britain, he said, which means a rich vein of work for consultants for the foreseeable future.
"As times get tighter and other environmental concerns start to bite, the way we do things change," he said.
"The choices of the past such as building a bypass or just adding more lanes to a motorway are no longer acceptable in many cases, or even affordable, so there's room to look at doing things differently.
"And all that means work for us."