This section contains information about weather conditions that may help you avoid contracting Valley Fever if you live in an endemic area. If you have to be outdoors during high-risk conditions, a simple dust mask is NOT enough. NIOSH-approved N95 and N100 paper respirators found in hardware stores technically could filter the arthroconidial Coccidioides spores but do not fit tightly enough around the wearer’s face to provide adequate protection. A miner’s mask or other respiratory equipment with a more secure seal would be needed for true protection.
Ultraviolet light (UV) from the sun can kill Coccidioides spores. The fungus lives in the soil in the hot, sunny desert and infects people when it is carried through the air. Since the disease still exists, natural UV is obviously not sufficient to kill all or even most of the spores that can cause infection at any time. Dawn, dusk, and night are the times with the least UV from sunlight.
Anyone can contract a Coccidioides infection at any time of day or night in an endemic area. Digging, working, or playing in soil that harbors this fungus are dangerous behaviors.
In Arizona the largest outbreaks are usually recorded from June through July and October through November. In California the larger outbreaks recorded are from May through November. Valley Fever can be contracted all year round but studies have shown that larger outbreaks tend to follow major rain and drought cycles.
The section below offers precautions about specific examples of weather conditions. These safety precautions apply to all parts of the endemic areas, including cities and suburban communities.
At the dawn of a new day it can be windy and hazy in the desert, with air currents lifting dust into the air. The cocci spores are alive and well in their endemic areas at this time of day. Even if you are in the city or miles away from the open desert, you can inhale the spores that cause Valley Fever. You don’t have to be in the desert itself.
Note: Although dust may be mingling with airborne Coccidioides spores (called arthroconidia), remember that these spores are microscopically small, not visible to the naked eye, and not attached to the dust itself.
On a clear day in the desert with no wind to blow dust around, chances of contracting Valley Fever may be reduced.
However, if you are in an area where construction is happening (such as new roads, office buildings, housing, etc.), working in the ground itself (gardening, playing close to the ground, crawling, etc.) the danger increases. Automobiles passing by, machinery in use, or any other activity that can lift dust into the air can cause a case of Valley Fever if cocci spores are present and inhaled.
On a windy, hazy day in the desert, city, or even near your home, you should take precautions. Instead of golfing or hiking on a windy day, do indoor sports or other activities to lessen your risk of contracting Valley Fever. Avoid spending the day outdoors because the possibility of contracting a Valley Fever infection is dramatically increased due to the soil disturbances the wind can cause. It is advisable to keep your children and pets inside during these weather conditions.
If you are driving, closing your vents and windows and setting the ventilation system to “inside air” will reduce the risk of airborne spores entering the vehicle. Valley Fever Survivor is proud that we were the first to share this simple, potentially lifesaving measure in 2002.
A peaceful, beautiful desert sunset, without wind, can be easily enjoyed. While this has similar risks to a still day with sunlight, care should always be taken. As noted earlier, the lack of airborne dust or wind does not guarantee that there are no Coccidioides spores nearby to be inhaled.
This is one of the most dangerous scenarios, along with the complete fall of night when the wind and dust are blowing. We suggest that you avoid going outside on a windy night. Even a simple trip to the supermarket might bring cocci to your lungs when it could have been avoided. The lack of UV and presence of wind can allow cocci spores to travel hundreds of miles.
Not every inch of the endemic areas contain Coccidioides spores, but it is always wise to take precautions. Also please remember that the conditions that are unsafe for you are also unsafe for your children and pets.