Study Guide: Air Quality and Smoke Days
Major fires will become more frequent in California. Everyone needs to be prepared. During recent fires, misleading information was widely propagated, leading some to believe that driving children through smokey conditions to sit in poorly-filtered classrooms was their best option. The US EPA, a more credible source of information, states:
“Fine particles, called “particle pollution,” are the pollutant of most concern in wildfire smoke. These microscopic particles can get deep into your lungs. They can cause many health problems from burning eyes and runny nose to aggravation of chronic heart and lung disease, leading to emergency department visits, hospital admissions and even premature death. Anyone with heart and lung disease is especially at risk. While not everyone reacts the same way to wildfire smoke, it’s always a good idea to reduce your exposure to smoke."
Source: www3.epa.gov/airnow/airaware/wildfires.html
Frequently Asked Questions
1. Is any amount of smoke damaging?
Yes. Any amount of smoke is damaging to the lungs, more so to growing or weakened lungs. As the US EPA states, “it’s always a good idea to reduce your exposure to smoke.”
2. What does it mean to say that some people are sensitive to smoke?
Such foolish comments actually refer to the overly sensitive, such as those with compromised respiratory or circulatory systems. Describing one group of people as “sensitive” implies that other groups are not. This leads officialdumb to make artificial distinctions and create one set of rules for the “sensitive” and anther set of rules for everyone else. In reality, we are all sensitive to smoke, and we all sustain at least some permanent damage from the particulate matter in smoke.
3. What are the dangers in wildfire smoke?
Smoke from wildfires contains many different toxins in the form of particulate matter and vapor. When forests burn most of the particulate matter in smoke is formed from burning vegetation. When buildings, vehicles and factories burn, an extremely toxic mix of pollutants is produced.
4. How much particulate matter is dangerous?
All particulate matter is dangerous. The more particulate matter there is in the smoke, the more dangerous it is. There is no minimum safe exposure level.
5. What kinds of particulate matter are most dangerous?
The most dangerous particulate matter are very fine particles, often referred to as PM2.5. These particles are less than 2.5 microns in diameter. They can be invisible and odorless. PM2.5 particles can linger in the air for days and float to far away regions that were otherwise unaffected by the fire.
6. What is PM2.5 particulate matter?
PM 2.5, are the smallest and most dangerous particles in smoke. They are 2.5 microns in diameter or less.
7. Why is PM2.5 particulate matter so dangerous?
Small particles can travel deep within the lungs, where they are difficult to cough out, and can more easily cross the blood barrier. Once such particles enter the blood they are free to travel throughout the body, and can cause or contribute to serious diseases in many different organs.
8. Is the smoke from distant fires safer than the smoke from nearby fires?
No. As smoke floats away from the fire, the largest and heaviest particles drift to the ground in the form of ash. These are not the most dangerous particles because they are easier for the mucus membrane to filter out and the lungs to cough out.
The longer smoke stays in the air, the higher the percentage of very fine particles remaining in the smoke. For this reason, smoke from faraway fires can potentially cause more long term health damage than smoke from nearby fires.
9. Is it better to go to school or shelter at home?
The US EPA advises, “When it’s smoky outdoors, try to stay indoors.” (https://www3.epa.gov/airnow/airaware/wildfires.html)
Driving to school (often in long commutes through heavily polluted areas) is not staying indoors. The best place to be when air pollution is high is usually right where you are with the doors and windows closed, preferably in your own home where you have what you need to wait out the emergency.
10. Is the air in school classrooms better than the air at home?
Probably not. If your child attends a typically underfunded public school, the classrooms are very unlikely to have poor-quality air filtration systems. The clerical staff in some school districts, may claim that school classrooms have better air than your home. This is rarely true for the following reasons:
- Poor air filtration: Most schools use inexpensive or unmaintained air filters, such as MERV11 filters. These filters are useless against the particulate matter in smoke. The best such systems can do is blow the smoke particles through the classroom.
- Poor construction: Many classrooms are housed in cheap portables with ancient, inefficient air filtration systems and poorly maintained walls and windows. There are many ways for outside air pollution to enter such structures even when doors and windows are closed.
- Too much activity: It is impossible to keep a classroom full of energetic students quiet enough all day long to prevent exposure to outside air or to prevent disturbing the dust that may have settled in the room. As students and teachers enter and exit the classroom multiple times per day, they inevitably circulate large amounts of outside air into classroom and circulate the dust already in the room.
- Getting there: Many of us live a long way from school. During long commutes we may pass through areas of extremely high levels of pollution. Few vehicles are equipped to filter out fine particulate matter, such as PM2.5.
10. What rating of air filter should we install in our home?
Many air filtration systems use filters measured with a MERV efficiency rating from 1 to 20. To protect your home from PM2.5, you should install filters with a rating of MERV 17 or higher.
| MERV Rating | Efficiency | PM 2.5 Protection |
|---|---|---|
| MERV 1-4 | Low: Usually made of a 1” think mat of fiberglass fibers. | ✗ |
| MERV 5-8 | Medium-Low: Can significantly improve air quality in a home, but are almost completely useless against the particulate matter in smoke. | ✗ |
| MERV 9-12 | Medium-High: Can significantly improve indoor air quality, but are useless against most particulate matter in smoke. | ✗ |
| MERV 13-16 | High: Can reduce indoor particles by as much as 95 percent, but are useless against the most dangerous particulate matter in smoke, such as PM 2.5. | ✗ |
| MERV 17-20 | High Particulate Air (HEPA): Have a High Efficiency Particulate Air (HEPA) rating. These are the most efficient filters, and the only ones that can filter out PM 2.5 particles. | ✓ |
11. Will my home air filtration system handle a MERV 17 or higher filter?
Maybe. More efficient filters are often much thicker, and so may not fit into your system. You may need to consult a heating and air technician or the manufacturer of your air system to confirm which high efficiency filters will work. If you can’t switch to a more efficient filter, running the system continuously by switching the thermostat fan from “Auto” to “On” has been shown in some studies to reduce particle concentrations over time.
12. How else can we protect ourselves inside the home?
There are many effective ways to protect your home from outside smoke, including:
- Upgrade and prepare your central air system filters: Ask a heating, ventilation and air conditioning (HVAC) professional what kind of high efficiency filters (rated MERV 17 or higher) you can use in your home’s HVAC system. Keep a few extra high quality air filters ready for use.
- Minimize outside trips: In advance of a smoke event, create an emergency kit with enough food, water and other supplies to provide for your whole family for at least three weeks. This will help minimize the need to go outside to shop.
- Create a “clean room”: In advance of a smoke event, choose a room in your home where you and your family can shelter in place. This room should not have a fireplace, and should have few windows and doors. A large bedroom is often a good choice. Stock the room with books, games, art supplies, musical instruments, movies, munchies, water, blankets, duct tape, toilet paper, battery operated lighting, emergency kits, emergency radio, etc.
- Get high-efficiency portable air filters": In advance of a smoke event, get a portable air cleaner that is the right size for the room where you plan to spend most of your time. Make sure it does not make ozone.
- Cover air leaks: In advance of a smoke event, make cardboard or plastic covers to tape over any problem openings in your home. If your home uses natural gas, be sure such appliances are either correctly turned off or remain adequately vented. Learn how to close the fresh-air intake if your HVAC system or room air conditioner if it has one.
- Contain children and pets: Keep children and pets inside as much as possible. Plan on spending long periods of time together in your safe room.
13. What is a face mask?
A face mask is a loose-fitting, disposable device. If worn properly, it can help block most large-particles from reaching the mouth and nose. A face mask is not very effective at filtering out very small particles. Face masks also do not provide complete protection from contaminants because of the loose fit between the surface of the face mask and your face. Face masks do NOT offer much if any projection if you have facial hair along the edges of the mask or if the mask does not fit tightly to you face.
14. How long can I use a face mask?
Face masks are not intended to be used more than once. Used face masks should not to be shared with others. If your mask is damaged or soiled, or if breathing through the mask becomes difficult, you should remove it, discard it safely, and replace it with a new one. To safely discard a mask, place it in a plastic bag and put it in the trash. Wash your hands after handling a used mask.
15. Can children use a face mask?
Yes! Authoritative-sounding pronouncements often claim that face masks are useless for children. This is NOT true. A well-fitting face mask used correctly is far better than no protection at all. N95 face masks in children’s sizes are harder to find in an emergency, but ridiculously easy to find if you plan ahead. For example, by clicking here:
16. What is an N95 face mask?
The N95 mask can filter up to 95% of airborne particles if warn correctly. N95 masks can not filter out PM2.5, the smallest and most dangerous particles in smoke. The “N” in N95 means, “No protection from oil”. These masks DO NOT protect against oil, oil-based solvents. N95 masks may provide some protection from the smoke of a forest fire, but they CAN NOT protect against the smoke from urban fires which often contain an extremely toxic mix of pollutants.
17. Are there better options than the N95 face mask?
Yes. There are several better options, including:
- N99 face mask (Filters up to 99.9%; no protection from oil-based toxins)
- P100 (Filters up to 99.9%; provides protection from oil-based toxins; half face respirator; no protection for the eyes)
- P100 (Filters up to 99.9%; full protection from oil-based toxins; full face respirator; includes a faceshield to protect the eyes)
18. What is a P100 respirator?
The “P” stands for “Protection from oil”. This means the respirator is effective even against the toxic mix of solvents and fumes produced in urban fires. The “100” means that the respirator will filter out 99.9% of all particles, including PM2.5.
19. Should I get a P100 respirators for each member of my family?
Yes.
Where can I get P100 respirators?
Your local hardware store. Ask for an OSHA approved respirator. Amazon also carries them: https://www.amazon.com/s?k=p100+respirator+mask
More Information
US NOAA Weather Forecasts
Air Quality Forecast Guidance for Sonoma, CA
US EPA Wildfire Smoke Fact Sheet
- http://localhost:1313/docs/general/indoor-air-filtration-factsheet-508.pdf
NIOSH-Approved Particulate Filtering Facepiece Respirators
PurpleAir
PurpleAir is a proven, shared-source air quality monitoring solution for private citizens and air quality professionals alike. It uses a new generation of laser particle counters to provide real time measurement of PM1.0, PM2.5 and PM10.
The PurpleAir network of sensors update every 120 seconds, providing real time readings to the PurpleAir Map. In most areas, this system is more reliable and accurate than the government’s own AQI system which has fewer sensors and is not updated as often.
NOAA-EPA Air Quality Index (AQI)
The following simplified warning system uses a complex formula to estimate average risks from a mix of typical airborne factors, some of which are unrelated to fires. For this reason, it is not always an accurate measure of local risks from wildfire smoke. Still, it is better than nothing. It is best to shelter in place whenever the AQI reaches or exceeds 100. (It is strongly advised to ignore any pronouncements from officialdumb who may claim that AQI estimates above 100 are also safe!)
