SAN FRANCISCO (KRON) — Plumes of smoke from wildfires in Northern California and Oregon have covered the Bay Area starting Tuesday. On Wednesday, a Spare the Air Alert was issued through Thursday due to the higher levels of particulate matter in the air, the Bay Area Air Quality Management District announced. Residents have been advised to avoid exposure if the smell of smoke is present by staying indoors and closing all doors and windows.

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Bay Area air quality updates:

10:00 p.m. — Air quality concerns remain in South Bay, East Bay

The unhealthy air quality continued throughout Wednesday in the Easy Bay and South Bay. The smoke was visible in both areas, though that didn’t stop people from going outside.

Dr. John Balmes with UCSF says people with pre-existing conditions are affected most by the air. He says anyone who has one of these conditions and plans on attending Thursday’s 49ers home opener should wear a mask.

5:30 p.m. — Wildfire smoke causes unhealthy air conditions for North Bay residents

12:47 p.m. — USF on-site instruction suspended

The University of San Francisco is suspending all on-site instruction Wednesday at USF campuses and additional locations, according to an announcement from school officials. Campuses affected include Hilltop, Downtown, Sacramento, San Jose and Santa Rosa. In addition, Koret Health and Recreation Center, Gleeson Library and Zief Law Library will also be closed. USF said dining and housing services will remain open and staffed.

11:11 a.m. — Red Flag Warning issued

A Red Flag Warning was issued by the National Weather Service for interior North Bay mountains that goes into effect Wednesday at 11 p.m. and ends Thursday at 5 p.m. The warning means that critical fire weather conditions exist now or will occur shortly. It does not relate to the smoke in the Bay Area coming from Northern California and Oregon. The NWS said the combination of gusty winds and low humidity can cause fire to rapidly intensify and grow in size.

(Image: National Weather Service Bay Area)

10:36 a.m. — Oakland Zoo closed Wednesday

The Oakland Zoo announced on X that it will be closed Wednesday due to poor air quality. The zoo added that its animal care team is “making sure all of our animals are comfortable and healthy.”

9:57 a.m. — Oakland school district issues “poor air quality” protocols

The Oakland Unified School District said Wednesday the air quality in Oakland is on the edge of the Environmental Protection Agency’s categories of “Unhealthy for Sensitive Groups” and “Unhealthy.” In response, the district will be instituting poor air quality protocols. Staff are instructed to close the doors and windows of classrooms, turn HEPA filters in classrooms and offices to “high,” keep students with sensitivities to air quality, such as asthma, indoors, and move all activities indoors at an air quality index (AQI) of 151 or higher.

The Fremont Unified School District said that schools in the city will be open Wednesday with some modifications due to the poor air quality. These modifications include keeping windows and doors closed, moving physical education classes indoors when possible and moving recess and lunch indoors when possible. Fremont school officials said that after-school activities and sports would be modified as needed and that information would be sent from specific schools to parents of students.

On Tuesday, the San Francisco Unified School District said it is also monitoring air quality in San Francisco and expects the higher AQI to last through Thursday. The district said its schools can stay open based on state guidance, “even if they need to close their windows or decrease outdoor air intake by the ventilation system during these times.” SF school officials also said portable air filters that HEPA filtration can maintain healthy air quality in schools along with the HVAC systems.