Show HN: Home Made Air Purifier
Note: this is not my idea, but I have used it for 2 Cal fire seasons successfully.
1) Acquire a box fan
2) Acquire a large "FPR 10" rated filter from home depot
3) Duct tape filter to the out flow side of the box fan. Make sure the arrows on the filter point in the correct airflow direction.
This works dramatically well for very little dollars and can help save your lungs if air purifiers are not available or expensive.
Also, check air quality of live sensors on purpleair.com (no affiliation)