Wildfire Smoke Frequently Asked Questions


What is in wildfire smoke?

  • Smoke is a complex mixture of carbon dioxide, water vapor, carbon monoxide, particles, hydrocarbons and other organic chemicals, nitrogen oxides, and trace minerals.
  • Fine particles are the principal pollutant of concern from wildfire smoke for short-term exposures (hours to weeks).

What are some of the health effects of wildfire smoke?

  • Fine particles can be inhaled deeply into the lungs; exposure to the smallest particles can affect the lungs and heart.
  • Fine particles are respiratory irritants, and exposure to high concentrations can cause persistent cough, phlegm, wheezing, and difficulty breathing.
  • Exposure to fine particles can affect healthy people, causing respiratory symptoms and reductions in lung function. Particle pollution may also affect the body's ability remove foreign materials from the lungs, such as pollen and bacteria.
  • Studies have found that short-term exposure (i.e., days to weeks) to fine particles, a major component of smoke, is linked with aggravation of pre-existing heart and lung disease. 

Are some people more affected than others?

  • Not everyone who is exposed to wildfire smoke will have health problems. Age, individual susceptibility – including the presence or absence of pre-existing lung (e.g., asthma, COPD) or heart disease, and other factors – determine whether someone will experience smoke-related health problems.
  • Most healthy adults and children will recover quickly from smoke exposure and will not suffer long-term health consequences. Certain sensitive people may experience more severe acute and chronic symptoms. 
  • Children, pregnant women, elderly individuals, and people who are sensitive to air pollution (such as those with pre-existing heart and lung disease) should take precautions to limit exposure to wildfire smoke.
  • Sensitive individuals concerned about the potential health implications of exposure to wildfire smoke should discuss this with their primary healthcare provider and check the Air Quality Index (www.airnow.gov) each day for the air quality forecast and for information about ways to reduce exposure.

What if I have asthma or another lung disease, or I have heart disease? 

  • If you have asthma or another lung disease make sure you follow your healthcare provider’s directions about taking your medicines and following your asthma action plan. Have at least a five-day supply of medication on hand. Call your healthcare provider if your symptoms worsen.  For individual concerns from specific smoke events, consult a medical professional.
  • If you have cardiovascular disease, follow your healthcare provider’s directions and call if your symptoms worsen. If you think you are having a heart attack or stroke, dial 9-1-1.

How will I know if smoke will be in my area?

    Additional Information

  • The AQI is used to report information about the most common air pollutants, including particulate matter (PM2.5 or PM10) and ozone. For more information, visit www.airnow.gov
  • The AirNow website, at www.airnow.gov is a multi-agency website run by EPA that reports air quality using the AQI. The AirNow program accepts, stores, and displays data provided by air quality agencies. Agencies submit continuous PM data to AirNow from over 1,200 PM2.5 monitors and 500 PM10 monitors, plus temporary monitors that monitor smoke on an hourly basis. These data are available to the public via national, regional, and local maps on airnow.gov and through email notifications, widgets, and smart-phone apps.
  • Many local news and local air quality agencies report air quality forecasts on their websites.

How can I reduce exposure to wildfire smoke?

  • For people in a safe location, away from the fire, reducing physical activity is an effective strategy to lower the dose of inhaled air pollutants and reduce health risks during a smoke event. During exercise, people can increase their air intake as much as 10 to 20 times over their resting level. Increased breathing rates bring more pollution deep into the lungs.
  • Staying inside in a safe place with the doors and windows closed can usually reduce exposure to air pollution by at least a third or more. 
  • If you have a central air conditioning system in your home, set it to re-circulate or close outdoor air intakes to avoid drawing in smoky outdoor air. Consider upgrading your filter to a HEPA filter with the highest MERV rating suitable to your system. Refer to user manual. 
  • Reduce other sources of indoor air pollution: smoking cigarettes, using gas, propane and wood-burning stoves and furnaces, spraying aerosol products, frying or broiling meat, burning candles and incense, and vacuuming can all increase particle levels in a home and should be avoided when wildfire smoke is present.
  • People who wish to clean their residences after wildfire smoke events should use cleaning practices that reduce re-suspension of particles that have settled, including damp mopping, damp dusting and using a high efficiency particulate air [HEPA] filter-equipped vacuum.
  • Portable air cleaners using High-Efficiency Particulate Air (HEPA) filters and ElectroStatic Precipitators (ESPs) can help reduce indoor particle levels, provided the specific air cleaner is properly matched to the size of the indoor environment in which it is placed, and doors and windows are kept shut. Check to make sure the device does not produce ozone; those devices may increase indoor air pollution.  California Air Resources Board maintains a list of portable air cleaners that are certified by the State to not emit excess ozone. The California Air Resources Board also provides guidance on selecting an air cleaner at: https://www.arb.ca.gov/research/indoor/aircleaners/certified.htm.
  • Some communities have designated clean air shelters where people can go for respite from smoky conditions. This is particularly important for people without air conditioning on hot smoky days, when staying indoors with windows closed can be hazardous. Places to consider going include public libraries, hospitals, movie theaters, and other public buildings with good HVAC systems.
  • Individuals who are particularly sensitive to smoke should consider temporarily evacuating an area with unhealthy levels of air pollution until air quality conditions improve. 

Should I wear a mask?

  • Respirator masks can be effective in reducing exposure to smoke particles, however they should only be used after first implementing other, more effective methods of exposure reduction, including staying indoors with doors and windows closed, reducing activity, and using HEPA air cleaners indoors to reduce overall smoke exposure. 
  • For adults, NIOSH N95 or P100 masks, when worn correctly, have been shown to filter particles and improve the quality of the air being inhaled. 
  • Masks can be ordered online or purchased at hardware stores. 
  • People with respiratory or heart conditions should consult with their healthcare provider prior to wearing a respirator mask. 
  • Effective masks are labelled NIOSH N95 or P100 and must fit properly or they are ineffective. 
  • Surgical masks, dust masks, and bandanas or other face coverings do not offer protection from particle pollution. 
  • Children should not wear these masks – they do not fit properly and can impede breathing. If the air quality is poor enough that a child requires a mask, the child should remain indoors, in a safe place, and evacuation should be considered.
  • For information on using masks for wildfire smoke see: https://airnow.gov/static/topics/images/epa-infographic-respirator.jpg.

If the air is smoky and hot, what can people do to protect their health when they do not have air conditioning/HVAC?

  • Leaving the area may be best for those with health conditions that put them at higher risk for illness.
    • Go to a local public building with air conditioning such as a movie theater, mall or library.
    • Seek a local clean air shelter.
    • Seek shelter at a friend or relative's home away from smoke.
  • If you must stay put:

When should local officials issue warnings or cancel local activities?

  • School and local officials should consider the following and consult the Wildfire Smoke: A Guide for Public Health Officials when deciding to close or curtail local activities or events due to wildfire smoke:
    • Is the activity being held inside or outside?
    • Do smoke levels reduce visibility and make it unsafe to travel to the activity?
    • Are highly sensitive groups such as asthmatic children participating?
    • What time of day will the activities be held?
    • Are smoke forecasts available for the day? Based on the smoke forecast, will the smoke level be higher or lower at the time of the activity and at the time individuals will be traveling to the activity?
    • Are smoke levels inside public buildings likely to be similar to or lower than those in private homes? For example, if local populations do not have air conditioning and the activity is held inside a public building that does have air conditioning and it is hot and smoky outside, it may benefit the public to seek relief indoors.
    • Is it practical to cancel part of the activity?
    • Are smoke forecasts likely to put any or all populations at increased risk? See below for Recommended Actions.
    • Is it practical to continue with the event as planned but issue a warning for sensitive groups? For example: holding the high school football game but issuing a warning that encourages sensitive groups — such as grandparents and young children — to stay at home and not attend the event?

Recommended Actions for Public Health Officials
Air Quality Index (AQI) Category (AQI Values) Level of Fine Particles in the Air measured in micrograms per cubic meter Recommended Actions

Good
(0 to 50)

 

0-12

  • If smoke event forecast, implement communication plan

Moderate
(51 to 100)

12.1-35.4

  • Prepare for full implementation of School Activity Guidelines (https://www3.epa.gov/airnow/flag/school-chart-2014.pdf)
  • Issue public service announcements (PSAs) advising public about health effects, symptoms and ways to reduce exposure
  • Distribute information about exposure avoidance

Unhealthy for Sensitive Groups
(101 to 150)

35.5-55.4

  • Evaluate implementation of School Activity Guidelines
  • If smoke event projected to be prolonged, evaluate and notify possible sites for clean air shelters
  • If smoke event projected to be prolonged, prepare evacuation plans

Unhealthy
(151 to 200)

55.5-150.4

  • Full implementation of School Activity Guidelines
  • Consider canceling outdoor events (e.g., concerts and competitive sports), based on public health and travel considerations

Very Unhealthy
(201 to 300)

150.5-250.4

  • Schools move all activities indoors or reschedule them to another day.
  • Consider closing some or all schools  
  • Cancel outdoor events involving activity (e.g., competitive sports)
  • Consider cancelling outdoor events that do not involve activity (e.g. concerts)

Hazardous
(> 300)

>250.5-500

  • Consider closing schools
  • Cancel outdoor events (e.g., concerts and competitive sports)
  • Consider closing workplaces not essential to public health
  • If PM level is projected to remain high for a prolonged time, consider evacuation of at-risk populations

What are the health effects of ash?

  • Ash may be irritating to the skin, nose, and throat, and may cause coughing. Fine particles can be inhaled deeply into lungs and may aggravate asthma and make it difficult to breathe.
  • People with asthma or other lung diseases, pregnant women, children, and older adults should not be in the vicinity while cleanup is in progress because it is easy to stir up ash. Do not allow children to play in ash. Clean all children’s toys before using. Clean ash off pets and other domesticated animals, and do not allow pets on contaminated sites.
  • AVOID direct contact with ash. If you get ash on your skin, in your eyes, or in your mouth, wash it off as soon as you can.

    Additional Information

  • Fires often result in large amounts of ash, other debris (broken glass, exposed electric wires), and contaminated dust, which may contain toxic substances such as asbestos, arsenic and lead. If your child is exposed to any of these substances, wash the child with soap and water as soon as possible and call Poison Control for further advice.
  • Cleanup efforts may expose you to ash and other fire decomposition products that may cause irritation and other health effects. Ash contains tiny particles (dust, dirt, soot) that can be deposited on indoor and outdoor surfaces and can be inhaled if the ash becomes airborne during cleanup. Ash from burned structures is generally more hazardous than forest ash.