Airborne chemical remains a mystery
Toluene not being used at tar ponds site, according to official agency
A dangerous chemical continues to appear in air monitoring tests although the source of the substance remains a mystery.
"On Aug. 31, at our Henry Street station in Whitney Pier, the reading was 4,000 micrograms per metres cubed," said Parker Donham, spokesperson for the provincial Sydney Tar Ponds Agency. "It was exclusively toluene."
The acceptable level of toluene listed in site separation zone criteria, while work is done at the Sydney coke ovens and tar ponds, is 760 micrograms per metre cubed.
The volatile organic compound is defined as a colourless flammable liquid obtained from coal tar or petroleum and used in aviation fuel and other high-octane fuels, in dyestuffs, explosives and as a solvent for gums and lacquers. It's also known as methylbenzene. At extremely high levels, the substance can cause tumours in humans. "The toluene readings have been occurring since July 2," said Donham.
The highest level recorded so far is 6,000 micrograms per metre cubed along King's Road in Sydney on Aug. 19.
"The fact that they've been showing up at diverse stations at times when the wind was blowing from the gauge toward the site rather than from the site toward the gauge makes us confident that the material is not originating on the site," said Donham. "We're not using any pure toluene for any purpose on the site right now."
Donham said no one else in the community is believed to be using the substance either.
The possibilities officials continue to investigate are: lab error, contaminated canisters, tampering of the air monitoring units, and that the substance is coming from within the airshed.
Donham said officials have increased monitoring activities to pin down the source. He declined to provide further details.
A detection of xylene is also causing concern. A reading Aug. 13, also at the Henry Street location, showed a level of 300 micrograms per metres cubed, said Donham. That exceeds the acceptable level of 36 micrograms per metres cubed.
Regulatory bodies were notifled of the high levels.