A contentious black cloud particulate emission at ArcelorMittal Dofasco on October 8 was only one of three reportable air pollution incidents by the steelmaker that weekend.

Neither the Ministry of Environment and Climate Change nor ArcelorMittal Dofasco had previously acknowledged the additional "events" on Thanksgiving weekend until asked by The Spectator this week.

"Yes, ArcelorMittal Dofasco (AMD) did report other incidents that occurred on October 8 and October 9 to the ministry. The additional events were related to the crane failure and shutdown of the steel making furnace," ministry spokesperson Gary Wheeler said Wednesday.

The issue came to public notice after Environment Hamilton executive director Lynda Lukasik photographed a dark cloud over the steelmaker at about 10 a.m. on Oct. 8. She happened to be bicycling in the area at the time.

She complained to the environment ministry, went public with the photos online and argued it was further evidence that the company's environmental handling of a hot iron temporary storage process called "coffining" was inadequate.

This led to Hamilton city council pressing the environment ministry last week to become more "aggressive" with the company and to host an air quality summit.

Coun. Sam Merulla, who introduced the motion, said Thursday that learning there were three incidents enlarges the concern but "I'm not surprised any longer. We've been abused, beaten and ignored for so long that nothing surprises me."

He noted the coffining issue has been going on for years, and he feels the ministry should be more rigorously enforcing pollution laws rather than working with companies over extended periods of time to try to mitigate environmental issues.

On Friday ministry staff met with company officials and this week the company outlined in a letter some technical processes it will do to try to lessen particulate pollution from coffining operations in the future.

Steelmakers use coffining when they have more molten iron than they can use in steelmaking. As a temporary measure the excess iron is placed in slag-lined outdoor pits to cool.

That can cause giant particulate clouds in the sky, especially when the pits are damp from rain. Prior to Thanksgiving weekend, there have been a total of seven coffining emission events reported this year, the company says.

The ministry was unable to confirm this. However, Lukasik says she has personally photographed 15 incidents over the past year, prior to Thanksgiving weekend.

As for the three incidents reported on Thanksgiving, the company says two were related to coffining and the third had to do with a technological issue during steelmaking. However, the ministry says its records show all three were coffining, two on Oct. 8, one on Oct. 9.

The company says the crane failure on Thanksgiving weekend meant that hot iron had to be diverted from steelmaking and put through a coffining process.

The letter to the ministry this week, signed by the company's environmental manager Jim Stirling, said: "Since the events of October 8, ArcelorMittal Dofasco has established a team of experts with a mandate to fast track trials, deploy additional technologies and make process reconfigurations to eliminate eruptions and emissions."

The company says - in an effort to cut back on emissions - it is preheating coffining beds when rain is forecast to ensure they are hot and dry if needed. As well, the company is changing the manner in which the hot metal is poured into the coffining beds.

Meanwhile, the city's public health department says emissions from coffining operations are less of a public health concern than many other factory emissions because particles in a coffining-produced dark cloud tend to be larger.

Matt Lawson, health hazards manager with the city's public health services, says the emissions may look ominous. But it's actually industrial discharges that people can't see that are a greater threat to public health.

Ultra-small particles known as PM 10 (10 microns in size) and PM 2.5 (2.5 microns in size) "can get deep into our lungs. It goes into the alveoli where it becomes more of a health impact. Larger particles get filtered out by body defences like mucosal membranes and nose hair," he said.

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He also noted, "If this cloud doesn't make its way to be breathed in by anybody then there isn't anything to worry about in terms of health impact."

In the letter to the environment ministry, Stirling said, "The emission from this eruption fully dispersed in approximately one minute and did not leave ArcelorMittal Dofasco's property."

However, Lukasik said that was not what she observed. She said the emission did not stay on the property and floated over Eastport Drive and the beach strip.