A mobile air quality monitoring trailer. (Department of Environment)

While the quality of air in Saint John is getting better, one clean air expert is still concerned about levels of a toxic chemical in the air.

The Department of Environment released its air quality findings from 2009 in a report this week.

Gordon Dalzell, a member of the Citizens' Coalition for Clean Air, is troubled by levels in the air of the carcinogen benzene — a toxic chemical found in crude oil, gasoline, cigarette smoke and industrial emissions — even though it meets international standards.

"It's not the type of material you want to be in the ambient air. In fact you don't want it on your hands, any pathway to your body. And it is linked, there's no question, this substance is linked to cancer."

However, he said the Irving oil refinery has taken out some of the benzene in its gasoline to comply with American standards.

The report said there was a slight increase in 2009 in the Forest Hills and Champlain Heights areas, but that "benzene levels have not changed appreciably in the past three years at either site."

The reason for the increase wasn't listed in the report.

Dalzell said the East Saint John Marine Terminal is also installing technology that will reduce the amount of the benzene that escapes into the air.

That should be up and running in the fall.

The data collected in the 2009 report does show a decrease in the levels of two contaminants that contribute to acid rain.

The air quality index shows risk levels were low 98 per cent of the time and moderate the rest.

The report summarized results from 57 air quality monitoring sites and 12 acid rain monitoring sites.

Dalzell said there are multiple reasons behind the improved air quality.

"Coleson Cove is not working to its capacity. It's only about 13 per cent. And the Irving Oil Refinery did put in new technology to reduce sulphur dioxide."

"That's good news," said Dalzell. "There's a continuing downward trend."

The city of Saint John has been monitoring air quality levels since 1961.