By Nia Williams
REVELSTOKE, British Columbia (Reuters) - Millions of people in the western Canadian province of British Columbia were under air quality warnings on Monday as hundreds of wildfires filled the skies with smoke and turned the sun orange.
In the cities of Kelowna and Kamloops, the air quality index (AQI) was above 350, a "hazardous" level, real-time air quality information platform IQAir showed. AQI measures major pollutants including particulate matter produced by fires.
In comparison, Lahore in Pakistan was the world's most polluted major city in 2022 with an average AQI of 97, according to IQAir.
Wildfire smoke is a seasonal occurrence for much of heavily-forested British Columbia, but the number of wildfires and amount of land burned is trending higher as a result of climate change, increasing concerns about the impact on human health.
Forecasting service BlueSky Canada said nearly the entire province was covered by smoke, with the highest concentrations in the southern interior region where fires have forced around 35,000 people to evacuate over the past four days.
"This type of extreme smoke event covering all of our province does not happen every year," said Jalena Bennett, smoke information specialist with BlueSky Canada, adding 2018 was the last time wildfire smoke was so widespread.
Huge fires near the interior's biggest city Kelowna and around Shuswap Lake have destroyed an unknown number of homes, forcing the federal government to call in the military to help tackle blazes.
Environment Canada issued air quality advisories for much of the southern half of British Columbia, home to the majority of the province's 5.1 million inhabitants, including the densely populated Metro Vancouver region where smog hung in the sky.
In communities throughout the interior, smoke blotted out the mountains and dimmed the sunlight.
"Ash has been falling from the sky, my throat is itchy, my eyes are itchy," said Marie-Eve Hervieux, 31, a customer support manager living in Revelstoke, about 550 km (341 miles) northeast of Vancouver. "We don't know the long-term effects of breathing in this much smoke every summer."
Older adults, pregnant women, children and people with respiratory conditions like asthma are most at risk from inhaling smoke, according to the provincial government, which urged people to reduce physical activity outdoors.
Canada is enduring its worst-ever wildfire season and carbon emissions released by the fires are more then double the previous record.
Cooler weather and some rain in coming days is expected to help firefighters battling the blazes and bring temporary relief from the smoke, but the reprieve will be short-lived, said Bobby Sekhon, an Environment Canada meteorologist in Vancouver.
"We are going to be dealing with smoke into September because of the wildfires," he said.
(Reporting by Nia Williams; Editing by Denny Thomas and Josie Kao)