Add a brief smog advisory to the list of surprises that the Winter 2014 has foisted on Hamilton.

Though uncommon, the February smog advisory wasn’t a freak incident.

In fact, look for it become a more common occurrence as Environment Canada changes its air quality warning system.

It is revising the Air Quality Index into the Air Quality Health Index, which zeros in on key pollutants most likely to harm people. Those changes won't necessarily mean more warnings, but will likely affect when they arise and what factors prompt them.

'“We want people to learn more about it before it comes the official way to measure air quality.' - Jeff Coulson, meteorologist with Environment Canada.

Thursday's brief warning arose when a high pressure system crawling through southern Ontario, “light winds and a stagnant air mass” trapped pollutants in the Greater Toronto and Hamilton,” Environment Canada said in Thursday morning statement.

The agency warned the conditions could cause health problems for at-risk populations, including children, the elderly and people with respiratory illnesses.

Officials made the call based upon the air quality health index (AQHI), an equation that it has been testing out over the past nine years as a future replacement for the current air quality index (AQI).

“We want people to learn more about it before it comes the official way to measure air quality,” said Jeff Coulson, a meteorologist with Environment Canada.

The AQI, which Environment Canada has traditionally used to determine the cleanliness of the air, measures levels of several air pollutants — particulate matter, ozone, nitrogen dioxide, carbon monoxide, sulphur dioxide and total sulphur — and bases the pollution rating on the highest of the six readings. 

The AQHI, however, is based on an equation that measures the combined levels of just particulate matter, ozone and nitrogen dioxide, which are believed to have more harmful short-term impacts on health of high-risk individuals.

“The federal government wanted a standardized across Canada that would reflect the health impact of air pollutants so people could see it and make decisions about how they’ll go about their day,” said Denis Corr, an air pollution consultant in Hamilton.

Yesterday’s hours-long traffic jam in Hamilton, sparked by a morning collision on the 403, may have also contributed to the poor air quality in on Thursday, Corr said.

The AQHI is measured on scale of 1 to 10. When readings are between 1 and 3, the outdoor air quality is good and presents few health risks. When the air quality ranks in the 7-to-10 range, at-risk individuals should avoid doing strenuous activities outside, Environment Canada says. 

The agency is testing the AQHI in more than 50 of regions across the country, but has yet to adopt it as the nationwide standard.

As it’s rolled out, regions across the country can expect to minor changes in when cautions about air quality are released, Corr said.

Improving air quality in Hamilton

Even if Hamilton experiences more smog advisories going forward, it doesn’t mean the city’s air quality is necessarily getting worse. In fact, Corr said, air quality has actually improved better over the past decade.

Deaths related to air pollution have fallen 20 per cent since 2003.

'Even though air pollution has improved considerably in Hamilton, it is too high. —Denis Corr, environmental consultant

“In the wider context, even though air pollution has improved considerably in Hamilton, it is too high,” Corr noted. “The best data 180 to 190 people die of air quality here in Hamilton each year.”

Changes in weather

Thursday’s smog advisory was sparked by an uptick in airborne nitrogen dioxide in Hamilton and the Greater Toronto Area.

“Nitrogen dioxide affects the mucous membranes of the respiratory tract, eyes, nose, and throat,” said Matthew Adams, a doctoral student at McMaster University who specializes in the monitoring of air pollution.

“This irritation occurs with elevated exposure that may impair lung function and increase respiratory infections. The exposure to elevated NO2 may lower a person’s resistance to respiratory.”

Environment Canada downgraded and later cancelled the advisory on Thursday afternoon.

A low pressure system is set to blow into the Hamilton area over Thursday night, pushing the stagnant, relatively polluted air out of town.