Summer is approaching and many schools face risks from wildfires. So, for June’s Ask Nancy, we look at questions about how to be Preparing for Wildfire Smoke.

Question:

Is there a checklist for schools in wildfire zones that will help us get prepared for smoke related issues?

Nancy says:

While we’re in pre-wildfire season, this new EPA factsheet about preparing for wildfires is a great resource: https://www3.epa.gov/airnow/smoke_fires/prepare-for-fire-season.pdf.

WA State Department of Ecology has an Air Quality Monitoring webpage with the ability to launch a map of Washington State’s air monitoring sites, execute site reports, view recent data and link to other sites resources.  There is also a blog that county, state, and Federal agencies and Indian Tribes use to coordinate and aggregate information for Washington communities affected by smoke from wildfires. 

Schools prone to smoke events while school is in session might consider obtaining appropriate HEPA air filters.

The use of dust masks is voluntary.  Schools allowing voluntary use aren’t required to provide a medical evaluation or fit- testing for voluntary users of dust masks, but they are required to provide a free copy of the advisory information sheet found in WAC 296-842-11005 after determining voluntary use is a safe option for their workers.

Question:

What can our school be doing to ensure the best air quality in the buildings when there is wildfire smoke?

Nancy says:

Outdoor (ambient) air pollutants, including smoke, enter and leave buildings in three primary ways:

1. Mechanical ventilation systems, which actively draw in outdoor air through intake vents and distribute it throughout the building.

2. Natural ventilation (opening of doors or windows).

3. Infiltration, the passive entry of unfiltered outdoor air through small cracks and gaps in the building shell.

Tightly closed buildings reduce exposure to outdoor air pollution. Upgrading the filter efficiency of the heating, ventilating, and air-conditioning (HVAC) system and changing filters frequently during smoke events greatly improves indoor air quality. Supplementing with HEPA filters, particularly those with activated charcoal or other adsorbents, improves air quality even more.

During long-term smoke events, take advantage of periods of improved air quality (such as during rain or shifts in wind) to use natural ventilation to flush-out the building.

To reduce smoke particles in the building and their off-gassing, damp mop with microfiber cloths and use high efficiency (HEPA) vacuums or vacuums with high efficiency filter bags.

Reduce all sources of indoor air pollutants, including use of aerosols, fragrances, gas, propane or wood-burning stoves, smoking, etc.

 

Question:

How do we know when it is better to have the windows open or closed if wildfires have been happening?

Nancy says:

What you need to think about is how to maximize your building’s capacity to improve the indoor air quality.

When outside air is in the hazardous category (see the Department of Ecology Washington Air Quality Advisory Map), close all windows and minimize use of outside doors.  Under normal operations, mechanical ventilation air intake systems can supply approximately 15 -20 cubic feet per minute of outside air per person to flush out pollutants and keep CO2 levels below about 1000 – 1100 parts per million (ppm).

  • Close air intakes when outside air is in the unhealthy category. Indoor CO2 levels will probably rise.
  •  If possible, monitor CO2 levels. The eight-hour Washington Division of Occupational Safety and Health permissible limit for CO2 is 5000 ppm (WAC 296-841-20025). If CO2 reaches this level, the building will be uncomfortable. At about 4000 ppm, open air intakes to bring in outside air, preferably filtered.
  • If recommended by public health officials, use CO monitors with meters that can detect CO at levels as low as 1 ppm. Most hardware store CO alarms only detect potentially life-threatening levels of CO, not long-term, low-level exposures that still affect health. o California considered children when they set the current ambient air CO standard of 9 ppm CO averaged over 8 hours, and 20 ppm averaged over 1 hour. See California’s Evaluation of Air Quality Standards and Protection of Children (PDF). Low levels of CO can cause headache, dizziness, fatigue, weakness, confusion, and nausea.