Yes. Any amount of smoke is damaging to anyone with lungs, more so to those with growing or weakened lungs. Again, from the US EPA, “It’s always a good idea to reduce your exposure to smoke.”

This is a distinction without much of a difference. The idea of a sensitive group was invented to imply that everyone not in this group is not sensitive to smoke. However, according to the EPA the sensitive group includes all older adults, children, teenagers, and anyone working outdoors. Take special note of that last group, “anyone working outdoors”. In other words, it does not matter who you are, if you are in a situation where you must breathe smoke-filled air, you are in danger. If your lungs are young, growing, or already compromised, you are at even greater risk. The distinction become more ridiculous when considered together with the EPA’s own finding that any amount of smoke is dangerous for anyone with lungs.

Describing one group as “sensitive” implies that another group is not. This leads officialdumb (such as narrow-minded school administrators) to fixate on artificial distinctions, and create one set of rules for “sensitives” and anther for everyone else. In reality, everyone with lungs is sensitive to smoke and will sustain some degree of permanent damage.

Smoke from wildfires contains many different toxins in the form of particulate matter and vapor. When forests burn most of the particulate matter is from burning vegetation. In urban fires, where buildings, vehicles and factories may burn, an extremely toxic mix of pollutants is produced.

All particulate matter is dangerous. The more particulate matter there is in the smoke, the more dangerous it is. According to the EPA there is no minimum safe exposure level.

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. Because they are so small, 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.

PM 2.5, are the smallest and most dangerous particles in smoke. They are 2.5 microns in diameter or less.

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.

No. As smoke floats away from the fire, the largest and heaviest particles drift to the ground in the form of ash. These are usually not as dangerous 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. For this reason, smoke from faraway fires can potentially cause more long term health damage than smoke from nearby fires if it is breathed in for extended periods.

In most cases it’s better to stay home. The US EPA advises, “When it’s smoky outdoors, try to stay indoors.” (https://www3.epa.gov/airnow/airaware/wildfires.html) 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. If it is impossible to filter the air in your home, the next best option may be a local library or other public building with proper air filtration. In any case, driving to school every day, often in long commutes through heavily polluted areas, is not staying indoors.

Probably not. If your child attends a typically underfunded public school in the US, classrooms are likely to have poor-quality systems, with low MERV level filters. The clerical staff in some schools may claim that classrooms have better air than your home. This is rarely true for the following reasons:

1. Poor air filtration: Most schools use inexpensive or unmaintained air filters, such as MERV11 which are useless against the particulate matter in smoke. The “best” such systems can do is blow the smoke through the classroom.
2. 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 to enter such structures even when doors and windows are closed.
3. 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 and ash that may have settled inside the room. As students and teachers enter and exit the classroom multiple times per day, they inevitably circulate large amounts of outside air into classrooms and kick up the dust already in the room.
4. Getting there: Many live a long way from school. During long commutes we may pass through areas of extremely high pollution. Few vehicles are equipped to filter out fine particulate matter, such as PM2.5. The fact that you may not be able to see or smell the smoke inside you vehicle does not indicate that the air is safe. This twice-daily dose of heavy pollution can lead to long term health issues.

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. These are expensive and difficult to find.

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.	✓

Maybe. More efficient filters are thicker and 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.

There are many effective ways to protect your home from outside smoke, including:

1. 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.
2. 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.
3. 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.
4. 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.
5. 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.
6. 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.

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.

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.

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:

• https://www.amazon.com/s?k=childrens+n95+mask

Note: Many face masks sold for children are KN95. This type of mask is regulated in China, not in the US. Beginning in the Reagan years, most product inspections at US ports of entry were greatly reduced or eliminated. This creates ideal conditions for the importation of knockoff KN95 masks to be dumped into the US market.

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. N95 masks must be NIOSH approved. Here is a list of approved suppliers: https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/N95list1.html

A KN95 mask is the Chinese version of the N95 face mask. It has similar properties but its production quality is regulated in China. Beginning in the Reagan years, most product inspections at US ports of entry were greatly reduced or eliminated. This creates ideal conditions for the importation of knockoff KN95 masks to be dumped into the US market.

The “N” in N95 means, “No protection from oil”. These masks DO NOT protect against oil or 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 oil-based pollutants.

N95 masks are “single use only” because the oil in our skin immediately begins to break down the filter fabric. Such masks work as rated for only about 15 minutes even in the best of conditions. As soon as they become moist from a person’s breath, or absorb oil-based pollutants, they are useless.

Yes. There are several better options. See the following table.

Type	Filter	Description
N99 Face Mask	up to 99.9%	one-time use; no protection from oil-based toxins
P100 Half Face Respirator	up to 99.9%	extended-use; provides protection from oil-based toxins; ; no protection for the eyes
P100 Full Face Respirator	up to 99.9%	extended-use; full protection from oil-based toxins; includes a face shield to protect the eyes

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.

Yes.

Your local hardware store. Ask for an OSHA approved respirator. Amazon also carries them: https://www.amazon.com/s?k=p100+respirator+mask