The air quality is expected to remain "unhealthy" through Friday in the Northern Zone and Eastern Zone of the Bay Area.
An air quality advisory remains in place for all of Oregon through Thursday.
Wildfire smoke from the west coast has reached as far east as the Great Lakes region.
Portland faces hazardous air quality conditions while visibility is less than a mile in some areas.
Parts of California are experiencing hazardous air quality as a result of the smoke produced by the numerous wildfires.
The air quality in the Bay Area is expected to be at a moderate level from Thursday.
Vacaville faces very unhealthy levels of air pollution as wildfires burn across the region, producing heavy smoke.
"This is the most significant event in the past 50 years," said environmental health scientist Pablo Méndez Lázaro.
The author's of the assessment say cleaner air is also responsible for fewer work absences and premature births.
"Poisoning our environment means poisoning our own body," said researcher Yaron Ogen.
"I have never seen aerosol values so low in the Indo-Gangetic Plain at this time of year," said NASA scientist Pawan Gupta.
Residents of the city of Jalandhar in Punjab have been posting images on social media showing the snow-capped peaks of the the Dhauladhar mountain range.
A man sentenced for gang-raping a 23-year-old woman on a bus claims high levels of pollution in Delhi's air and water is already cutting his life short, using it as an argument to change his sentence.
The move is usually reserved for severe human rights violations.
New research suggests current air pollution standards are failing to protect human health and life.
Pollution in New Delhi peaked this month, reaching levels not seen in three years. In some parts of the city, the Air Quality Index approached 1,000—more than three times what is considered hazardous.
Scientists carried out the study after seeing exaggerated claims about the purifying powers of plants online.
During this time private cars with even number plates will only be permitted to drive on even dates and private cars with odd number plates will be restricted to odd dates.
Several fires are currently raging in various parts of the state.
"If possible, stay inside with windows and doors closed until smoke levels subside," the Bay Area Air District warned residents.
The now-20 strong panel will reconvene to consider the various known and unknown affects of particulate matter on human health and based on the current science, calculate how much air pollution (with an adequate margin of safety) is passable without being a significant threat to human health.
A smoke map using National Oceanic and Atmospheric Administration forecasts shows how pollution from the California fires spread to the U.S. East Coast.
The Camp Fire in California's Butte County created so much smoke that it made the air quality hazardous to breathe.
The Bay Area has been shrouded in a polluted haze due to nearby wildfires.
A norovirus outbreak has spread across evacuation shelters for the Camp Fire in California as smoke decreases the air quality to hazardous.
The air quality is extremely poor in some areas of California, and the National Weather Service in Sacramento has instructed residents to stay indoors.
"This measure, eagerly awaited by the inhabitants, is the fruit of an important partnership between the prefecture of police, mayors of the district and neighborhood associations," Mayor Anne Hidalgo said.
Local residents have been advised to shelter in place while officials get the blaze under control.