Here's the less wordy version of the link I posted above:
FIVE STEPS TO KEEP CHICKENS HEALTHY DURING SMOKY CONDITIONS:
PROVIDE FRESH WATER OFTEN
One of the most important things you can do to ensure your chickens stay healthy during smoky conditions is to provide as much clean, fresh water as possible. Fresh water will help to moisten airways and wash particulate matter away from the chicken’s beak and nostrils. Change the water often, to ensure that it is clean and free of toxins. We have noticed a large accumulation of film building up on our chicken’s water due to the smoke.
KEEP FOOD AND ENVIRONMENT DUST-FREE
Try to reduce any unnecessary dust that may be lurking in your chicken’s food or environment. Dusty conditions will further decrease air quality. If your feed is grainy or dusty, it may be a good time to ferment it. Fermented feed offers additional moisture, and it increases the bioavailability of nutrients. Providing extra nutrients is very important to combat the stress and fatigue caused by smoky conditions. Try to avoid dusty bedding material. It is also best to avoid changing bedding (unless absolutely needed) due to the amount of dust that is created by raking, shoveling, and replacing the bedding.
LIMIT ACTIVITY, IF POSSIBLE
Your chickens will most likely limit their physical activity during smoky conditions, which is perfectly natural and actually beneficial. Allow your chickens to rest and conserve energy. You may need to consider providing free range chickens with extra feed. This will help reduce the amount of physical exertion that is needed when searching and hunting for food.
WATCH FOR SIGNS OF RESPIRATORY DISTRESS
Monitor your chickens closely for respiratory distress and other health problems when conditions are smoky. Signs of respiratory distress can include wheezing, difficulty breathing, pale comb, discharge from nose or eyes and lethargy or fatigue. If you see consistent signs of respiratory distress, it is advisable to separate the effected bird, as infection can spread quickly. If signs continue or worsen, contact your avian veterinarian to develop a treatment plan. It is also important to continue monitoring animals after smoky conditions have improved because it can take several weeks for animals to fully recover.
MONITOR CONDITIONS ON A DAILY BASIS AND MAKE CHANGES AS NEEDED
One of the best things you can do to protect your animals during wildfire season is to trust your intuition! If you feel that conditions are worsening, if ash begins to fall, or if your animals are showing symptoms of distress, move them into a covered or indoor area if possible. A barn, garage or shed could be good options to provide temporary relief from smoky conditions