As of 11am PDT (7pm BST), the air quality index (AQI) in Seattle measured 185, a rating classified as “unhealthy”. The level means “everyone may begin to experience health effects, members of sensitive groups may experience more serious health effects”. In fact, the dismal air quality is so bad it is like smoking seven cigarettes a day, according to a research scale created by Berkeley Earth. The hazardous smog has been worse than in Beijing this week, where air quality levels are notoriously bad.Latest Seattle smoke map Seattle’s National Weather Service said visibility levels in Seattle today measured just two miles.What has caused the smoke? An outbreak of raging wildfires across the north west coast of the United States and British Columbia, Canada, is to blame for the choking conditions. The smoke was said to be so thick on Monday it masked the skyline and turned the sun a bright shade of red. Hundreds of flights have been grounded at Seattle-Tacoma International Airport due to the poor visibility.When will conditions clear? The National Weather Service has predicted a move to cooler temperatures and westerly winds over the next 48 hours, which should blow away much of the smoke for southern Washington where Seattle sits. In its latest update, NWS said: “The coastal areas and Southwest Washington should wake up to clean air tomorrow morning, and the rest of Western Washington will follow shortly behind. “Keep in mind that there could still be smoke from Vancouver Island fires that affects Clallam county and smoke from the Maple Fire that affects parts of Kitsap and Mason counties.” However, central and eastern Washington are likely to see conditions worsen temporarily before fresh air is brought in by rain at the end of the week.What are the health effects of wildfire smoke? Breathing in smoke from forest fires can be dangerous for everyone, especially sensitive groups such as people with heart or lung disease. Symptoms can include burning eyes, coughing, a sore throat, headache, shortness of breath and wheezing. When levels reach “unhealthy” for all persons, individuals are urged to limit their time outdoors and avoid strenuous activities. Check out the latest air quality index updates here.