Traffic moves along Main Street in Hellertown Wednesday, under a shroud of haze. The smog is a result of wildfires burning across Canada, and covers much of the Mid-Atlantic region, where air quality alerts are in effect.

Due to worsening air quality caused by smoke from wildfires ravaging parts of Canada, the Pennsylvania Department of Environmental Protection upgraded the Code Orange air quality alert it first issued Tuesday to a Code Red alert on Wednesday. Meanwhile, some local outdoor activities were postponed or canceled because of the unhealthy haze that blanketed the region.

The Promenade Shops at Saucon Valley announced that its weekly outdoor summer music series–Party at the Patio–would not be held Wednesday evening “due to air quality concerns.”

As another wave of Quebec-born wildfire smoke wafted southward across the Lehigh Valley Wednesday afternoon, the Code Red alert remained in effect for Northampton, Lehigh, Bucks, Montgomery, Carbon, Monroe and other counties in eastern Pennsylvania, where in addition to the haze an unpleasant, burnt odor filled the air. Some residents said the odor made them feel ill.

A Code Red alert is issued when air pollution rises to a level that has the potential to affect residents of all ages and without underlying health problems; a relatively rare occurrence in this area.

Above, two photos taken of the same section of South Mountain in Fountain Hill–near Bethlehem–show the dramatic increase in smog between Tuesday afternoon (top photo) and Wednesday afternoon (bottom photo).

Under the Environmental Protection Agency’s U.S. Air Quality Index, a Code Red classification means that “some members of the general public may experience health effects (and) members of sensitive groups may experience more serious health effects.” Examples of sensitive groups include small children, the elderly and individuals with heart and/or lung disease, asthma or other health conditions that may make them more susceptible to the negative effects of breathing polluted air.

According to a Guide for Particle Pollution published on the website AirNow.gov, when a Code Red alert is in effect, sensitive groups should avoid long or intense outdoor activities and consider rescheduling or moving activities indoors. All others should reduce their participation in “long or intense activities” and “take more breaks during outdoor activities.” For individuals who are members of sensitive groups, the use of air conditioning may be helpful, and the EPA advises that anyone staying indoors should not do so with the windows closed during spells of hot weather.

Fortunately, although it remains extremely dry across the Mid-Atlantic states, temperatures are lower than average for this time of year. Wednesday’s high in Allentown was forecast to be just 71.

Due to the lack of rain, combined with low humidity and breezy conditions, a Red Flag Warning is once again in effect for the Lehigh Valley area and beyond. A red flag warning means there is an elevated risk of wildfire due to weather conditions, and residents are being urged to exercise caution if handling any potential ignition sources, such as machinery, cigarettes and matches.

The DEP has issued another Code Orange air quality alert for the Lehigh Valley for Thursday in anticipation of continued poor air quality throughout the region.

Residents should continue to monitor local weather and air quality forecasts for updates on the situation.

PHOTOS BELOW of scenes in Hellertown borough contributed by Alec Bachman