Air Quality and Your Lungs: A Fresno Guide to Smoke and Allergy Season
By Dr. Harman Virk, DO — Board‑Certified Internal Medicine, The Modern Medicine Group (Fresno, CA)
Medical disclaimer: This article is educational and not medical advice. If symptoms are severe, worsening, or you’re worried—seek urgent care or call 911.
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Quick Take
The San Joaquin Valley traps air. Geography, agriculture, traffic, and wildfire smoke combine into some of the most challenging air in the country.
Fine particles are the main concern — small enough to reach deep into the lungs and enter the bloodstream.
Check the AQI the way you check the temperature, especially if you have asthma, COPD, heart disease, or a child at home.
On bad days, indoor air is your main tool: windows closed, air conditioning on recirculate, a good filter, and a portable HEPA unit if you can manage one.
Cloth and surgical masks do not filter fine particles. An N95 or KN95, properly fitted, does.
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Table of Contents
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1) Reading the AQI
The Air Quality Index converts measurements into a single number with color codes.
Green (0–50), Good: No precautions needed.
Yellow (51–100), Moderate: Unusually sensitive people may notice symptoms.
Orange (101–150), Unhealthy for Sensitive Groups: People with lung or heart disease, older adults, children, and pregnant women should limit prolonged outdoor exertion.
Red (151–200), Unhealthy: Everyone may experience effects. Sensitive groups should stay indoors.
Purple (201–300), Very Unhealthy: Everyone should avoid outdoor activity.
Maroon (301+), Hazardous: Emergency conditions. Stay indoors with filtered air.
Check it before outdoor work or exercise, using AirNow or the San Joaquin Valley Air Pollution Control District. Values change through the day, so a morning reading does not describe the afternoon.
One practical note: if you can smell smoke or see haze, treat the air as bad regardless of what the number says, since monitors are not on every corner.
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2) What to Do on a Bad Air Day
Stay indoors as much as possible, and keep windows and doors closed
Run air conditioning on recirculate rather than pulling in outside air
Postpone outdoor exercise, or move it indoors
Shift necessary outdoor work to early morning when levels are often lower
Keep rescue inhalers with you, not at home in a drawer
Avoid adding indoor pollution — no candles, incense, fireplaces, frying, or vacuuming without a HEPA filter
Set car ventilation to recirculate while driving
Stay hydrated
Check on older neighbors and relatives with lung or heart disease
Have a plan for where to go if your home cannot be kept clean — a library, mall, or community facility with filtered air
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3) Masks: What Works and What Does Not
Cloth masks and surgical masks do not filter fine particles. They were designed for droplets, and they will not protect your lungs from smoke.
N95 or KN95 respirators do, when fitted properly:
It must seal against your face; facial hair breaks the seal
Both straps go around the head, not looped over the ears, for a true N95
Check the seal by exhaling and feeling for leaks around the edges
Replace it when it becomes damp, dirty, or hard to breathe through
Anyone with significant heart or lung disease should ask their doctor first, since a respirator increases the work of breathing
They are not designed for small children
A mask is a supplement to staying indoors, not a substitute for it.
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4) Managing Asthma and COPD Through Smoke Season
Have a written action plan from your doctor, spelling out what to do at each level of symptoms and when to call.
Take controller medications consistently. These are the ones that prevent flares, and they only work when taken daily as prescribed — not just when you feel symptoms.
Keep rescue inhalers accessible and unexpired, and know how much is left.
Track your rescue inhaler use. Needing it more than usual is an early warning, and it is the signal to call before a flare becomes an emergency.
Get vaccinated against flu, COVID-19, RSV where indicated, and pneumococcal disease per your doctor’s recommendations. Respiratory infections stack badly with poor air.
Prepare before the season starts, not during it: refills in hand, action plan reviewed, filters purchased.
For what years of smoke exposure do to the lungs, see Modern Medicine’s related article, Long-Term Effects of Smoking on Your Health.
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5) Valley Fever: The Dust-Borne Infection to Know About
Coccidioidomycosis — Valley fever — is caused by a fungus living in Central Valley soil. It is inhaled when dust is disturbed, and this region is one of the highest-incidence areas in the country.
Higher exposure risk: agricultural and construction work, digging or grading, dust storms, off-road driving, archaeological work, and living in newly developed areas.
Symptoms, usually one to three weeks after exposure, can include:
Fatigue that is out of proportion to activity
Cough
Fever
Shortness of breath
Headache
Night sweats
Muscle or joint aches
A rash, sometimes tender red bumps on the lower legs
Many infections are mild and resolve on their own. Some cause prolonged illness, and a small share spread beyond the lungs — with higher risk in people who are pregnant, have diabetes, have weakened immune systems, or are of certain ancestries.
The practical point: a cough with fatigue that has lasted more than a couple of weeks in this valley deserves consideration of Valley fever. It is frequently treated as pneumonia or bronchitis first, and testing requires someone to think of it. It is reasonable to ask directly.
Reduce exposure by staying inside during dust storms, wetting soil before digging, keeping car windows closed on dusty roads, and using an N95 for dusty outdoor work.
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6) When to Call Your Doctor and When to Call 911
Call your doctor for:
Needing your rescue inhaler more often than usual
A cough that persists more than a couple of weeks
Chest tightness or wheezing that is new
Worsening exercise tolerance
Fatigue with fever or night sweats
Symptoms that do not settle once air quality improves
Any question about whether your action plan needs adjusting
Call 911 for:
Severe shortness of breath
Inability to speak in full sentences
Chest pain
Blue or gray lips or fingertips
Confusion or extreme drowsiness
A rescue inhaler that is not working
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7) Frequently Asked Questions
Does a cloth mask help with wildfire smoke?
No. Cloth and surgical masks do not filter fine particles. An N95 or KN95 with a proper seal is needed.
Is it safe to exercise outside on a moderate air day?
Most healthy adults are fine. People with asthma, COPD, or heart disease should consider indoor alternatives once the index reaches orange.
Do air purifiers actually work?
HEPA units meaningfully reduce indoor fine particles when properly sized for the room. Avoid ozone-generating devices.
How long after a fire does the air stay bad?
It depends on wind and weather, and can persist for days after the visible smoke clears. Follow the AQI rather than what you can see.
Should I be tested for Valley fever?
If you have had a cough, fatigue, or fever lasting more than a couple of weeks in this region — especially with dust exposure — it is worth asking about specifically.
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Fresno CTA — The Modern Medicine Group
If smoke season, dust, or allergy season leaves you reaching for a rescue inhaler more than usual, get your action plan reviewed before the next bad stretch.
The Modern Medicine Group manages asthma and COPD for Fresno patients, provides written action plans, evaluates persistent cough including Valley fever testing, and keeps vaccinations current ahead of respiratory season.
Visit: 7053 N. Cedar Ave., Fresno, CA 93720
Phone: 559-369-7787
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