This meant having plenty of open windows or an air purification system. But now the smoke we are experiencing because of the wildfires burning across California, has some concerned for the health of their children.
RELATED: Bay Area prepares for 'critical' fire conditions, smoky air
San Francisco parents we talked to said they were so happy their children were returning to in-person learning, that they haven't even thought about air purifiers in the classroom.
"I think they've got one, yeah, I think there's one there but I don't know," said one parent.
But Wednesday in San Francisco, the smoke was much more noticeable than earlier this week.
VIDEO: Smoke from CA wildfires brings ominous, orange skies to Bay Area
San Francisco Unified has told us because of COVID, they made sure to have good ventilation in all of the classrooms.
"In some classrooms that looks like lots of windows that open and in other classrooms that looks like making sure that there is mechanical ventilation," explained Gentle Blythe of the San Francisco School District.
But as wildfires continue to spread, opening windows isn't always advisable.
"Pollution, smoke plus respiratory viruses is a bad combination so it is worrisome. So really that's why ventilation systems are important," expressed Dr. Aruna Subramanian of Stanford Health Care.
WILDFIRE TRACKER: Interactive map shows where wildfires are burning in CA
To minimize the spread of coronavirus, some schools are requiring lunch be taken outside. That may not be practical if the air quality gets worse.
"We want our children to breathe the cleanest air possible, so it's definitely a concern that we have," said another San Francisco parent.
All classrooms in Oakland public schools have portable devices, according to the school district. Berkeley Unified says they too have one in each classroom. But keep in mind, Berkeley has 16 schools, where SF Unified is a much bigger district with 114 schools.
As of today, there are 775 portable air cleaners in classrooms across San Francisco Public schools. The school district said they will obtain a larger number once their current stock has been put to the test.