Worst U.S. cities for allergies by type: pollen, mold, and air quality compared
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Most allergy city rankings only measure one thing: pollen. They tell you Boise is bad and Houston is fine, and you are supposed to plan your life around that.
But pollen is not the only thing your body reacts to in the air. Mold is a second allergen that hits many of the same people, and fine particle pollution loads your airways on top of both. A city that ranks low for pollen can still wear you down through mold or dirty air.
Most rankings score one of these things. This comparison scores all three together, so you can see the full picture for your city.
Two scores in the table
Allergy load (out of 18) counts the two true allergens, pollen and mold. These trigger an IgE allergic response, the classic mechanism behind hay fever and mold allergy. Look at this score if allergies are your specific concern.
Airborne inflammation load (out of 26) adds fine particle pollution (PM2.5) on top. Particle pollution is not an allergen, so it stays out of the allergy score. But it inflames the same airways and makes allergic reactions worse, so it belongs in the fuller picture of what you breathe. This is the primary ranking below, and we call it inflammation load for short.
Where this data comes from
We scored 36 U.S. cities across three categories using public data from three sources. Each category is scored, and the scores are added together.
A city made the list if it is one of the 25 largest U.S. metro areas by population, or if it ranks in the top tier of a scored category: the AAFA top 10 for pollen or the American Lung Association worst 25 for year-round PM2.5.
Pollen (0-8): Based on the AAFA 2026 Allergy Capitals pollen subtotal rating, which measures tree, grass, and weed pollen counts. Worse than average = 8, Average = 4, Better than average = 1. We deliberately use the AAFA's pollen-only subtotal and strip out the two other things their overall ranking includes: how much allergy medicine people buy and how many allergists are nearby. Those measure healthcare access, not pollen. A city with brutal pollen but plenty of specialists can look fine in the overall ranking while still flooding your immune system with pollen.
Air quality (0-8): Based on the American Lung Association State of the Air 2026 report grading metro areas for year-round fine particle pollution (PM2.5). Worst 25 = 8, failing grade = 4, passing grade = 0. This counts toward inflammation load only, not allergy load.
Outdoor mold (0-10): Based on state-level mold allergy scores (average airborne spore counts per cubic meter, 0 to 100 scale) from HouseFresh analysis of monitoring data. Scored by tier: 60+ = 10, 50-59 = 8, 45-49 = 6, 40-44 = 5, 35-39 = 4, under 35 = 2.
Dominant pollen type comes from the AAFA 2026 report for the cities it names specifically. For the rest, it reflects the pollen patterns typical of that region.
Mold sensitization: from Quest Diagnostics IgE blood testing. This is the share of allergy patients in a city whose blood shows an immune reaction to mold. It measures the people, not the air, so it captures mold exposure that outdoor spore counts miss, including mold growing indoors. Quest only reports this for 10 cities, so we leave it out of both scores and discuss it in the analysis instead.
36 U.S. cities ranked by inflammation and allergen load
Ranked from highest (worst) to lowest total inflammation load. The allergy load column, in true allergens only, sits beside it so you can see which cities are driven by allergens and which by air quality.
| # | City | Inflammation load /26 | Allergy load /18 | Pollen | PM2.5 | Mold | Dominant Pollen |
|---|---|---|---|---|---|---|---|
| T-1 | San Diego, CA | 21 | 13 | 8 | 8 | 5 | Tree, grass, weed* |
| T-1 | San Francisco, CA | 21 | 13 | 8 | 8 | 5 | Tree, grass |
| T-3 | Chicago, IL | 20 | 16 | 8 | 4 | 8 | Tree, grass, ragweed |
| T-3 | Salt Lake City, UT | 20 | 12 | 8 | 8 | 4 | Weed dominant* |
| T-5 | Rochester, NY | 18 | 18 | 8 | 0 | 10 | Tree, grass, ragweed |
| T-5 | Austin, TX | 18 | 10 | 4 | 8 | 6 | Cedar, oak, grass, ragweed* |
| T-5 | Philadelphia, PA | 18 | 10 | 4 | 8 | 6 | Tree, grass, ragweed |
| T-8 | Bakersfield, CA | 17 | 9 | 4 | 8 | 5 | Grass, weed |
| T-8 | Los Angeles, CA | 17 | 9 | 4 | 8 | 5 | Tree, grass |
| T-10 | New York, NY | 15 | 11 | 1 | 4 | 10 | Tree, ragweed |
| T-10 | Dallas, TX | 15 | 7 | 1 | 8 | 6 | Cedar, oak, ragweed |
| 12 | Raleigh, NC | 14 | 14 | 8 | 0 | 6 | Oak, pine, grass |
| T-13 | Denver, CO | 13 | 13 | 8 | 0 | 5 | Tree, grass, weed* |
| T-13 | Greenville, SC | 13 | 13 | 8 | 0 | 5 | Tree, grass, ragweed |
| T-13 | Minneapolis, MN | 13 | 13 | 8 | 0 | 5 | Tree, grass, ragweed |
| T-13 | Tampa, FL | 13 | 13 | 8 | 0 | 5 | Oak, grass, ragweed |
| T-13 | Tulsa, OK | 13 | 13 | 8 | 0 | 5 | Tree, ragweed |
| T-13 | Atlanta, GA | 13 | 9 | 4 | 4 | 5 | Pine, oak, grass, ragweed |
| T-19 | Ogden, UT | 12 | 12 | 8 | 0 | 4 | Tree, grass, weed |
| T-19 | Portland, OR | 12 | 12 | 8 | 0 | 4 | Tree, grass, weed |
| T-19 | Provo, UT | 12 | 12 | 8 | 0 | 4 | Tree, grass, weed |
| T-22 | Wichita, KS | 11 | 11 | 1 | 0 | 10 | Grass, ragweed |
| T-22 | Houston, TX | 11 | 7 | 1 | 4 | 6 | Cedar, oak, ragweed |
| T-24 | Boise, ID | 10 | 10 | 8 | 0 | 2 | Tree, grass, weed* |
| T-24 | Charlotte, NC | 10 | 10 | 4 | 0 | 6 | Oak, pine, grass, ragweed |
| T-24 | Seattle, WA | 10 | 10 | 8 | 0 | 2 | Tree, grass |
| T-24 | Spokane, WA | 10 | 10 | 8 | 0 | 2 | Tree, grass |
| T-24 | Riverside, CA | 10 | 6 | 1 | 4 | 5 | Tree, grass |
| T-24 | St. Louis, MO | 10 | 6 | 1 | 4 | 5 | Tree, ragweed |
| T-30 | Miami, FL | 9 | 9 | 4 | 0 | 5 | Tree, grass, ragweed |
| T-30 | Orlando, FL | 9 | 9 | 4 | 0 | 5 | Oak, grass, ragweed |
| T-32 | San Antonio, TX | 7 | 7 | 1 | 0 | 6 | Cedar, oak |
| T-32 | Phoenix, AZ | 7 | 3 | 1 | 4 | 2 | Limited (desert species) |
| 34 | Boston, MA | 6 | 6 | 1 | 0 | 5 | Tree, grass, ragweed |
| 35 | Washington, DC | 5 | 5 | 1 | 0 | 4 | Tree, grass, ragweed |
| 36 | Las Vegas, NV | 3 | 3 | 1 | 0 | 2 | Limited (desert species) |
* Documented in AAFA 2026 report. Unmarked pollen types are based on regional patterns. Sources: AAFA 2026 Allergy Capitals pollen subtotal (pollen), American Lung Association State of the Air 2026 (PM2.5), HouseFresh/monitoring data (mold score), Quest Diagnostics IgE study (mold sensitization). Allergy load = pollen (0-8) + outdoor mold (0-10), true allergens only. Inflammation load = allergy load + PM2.5 (0-8). Pollen is scored from the AAFA's pollen-only subtotal, not the overall ranking which also includes medication and specialist access. Mold sensitization figures, available for 10 cities, are discussed in the analysis below rather than scored. Table and methodology by BiohackBeast.
What the rankings reveal
The worst cities are bad in multiple categories, not just one
San Diego and San Francisco tie for #1 on inflammation load, and neither one has the worst pollen in the country. Both land in the worst 25 for year-round PM2.5 while also carrying worse than average pollen. Cities with two or more elevated categories create a compounding effect: your immune system reacts to allergens while your lungs also process polluted air. Both drive the same low-grade inflammation, so the total load on your body is higher than any single ranking would suggest.
Chicago is the best example of a city that gets hit in every category at once. It is not the worst in the country for any single allergen, so a pollen-only or air-quality-only ranking would put it somewhere in the middle. But it carries worse than average pollen, failing PM2.5, and high outdoor mold (Illinois = 55/100) all at once, and 17% of allergy patients there test positive for mold. Add up the three scored categories and Chicago lands near the top.
Compare the two scores to see if your problem is allergens or air quality
Some cities score nearly the same on allergy load and inflammation load. That means pollen and mold are doing all the work and the air is clean. Rochester scores 18 on both. Denver, Tulsa, and Minneapolis score 13 on both. In cities like these, air quality is not part of the problem.
Other cities show a wide split. Austin, Philadelphia, Bakersfield, and Los Angeles all have modest allergy loads but jump 8 points once air quality is counted. Dallas nearly doubles. A pollen-focused reader in these cities would think they are fine, when particle pollution is quietly the bigger driver. This is exactly the burden that pollen-only rankings hide.
The AAFA's overall ranking includes medication and specialist data, not just pollen
This is the most important methodological detail most people miss. The AAFA's popular "Allergy Capitals" ranking combines pollen counts with over-the-counter medication purchasing and access to allergists. A city with brutal pollen but abundant specialists and lower medication sales can rank as "better than average" overall.
Austin is the clearest example. AAFA ranks it #81 overall because Austin has good access to allergists and relatively lower OTC medication purchasing. But the AAFA's own data shows Austin had one of the highest counts of "high" and "very high" tree pollen days of any city in the United States in 2025. Our pollen score uses the AAFA's pollen-only subtotal to strip out the medication and specialist noise.
Wichita is the opposite case. AAFA ranks it #1 overall for three straight years. But Wichita's pollen subtotal is actually "better than average." It ranks #1 because residents buy far more OTC medication and have very few specialists. The suffering there is real, but its #1 ranking is driven by poor healthcare access, not by extreme pollen exposure.
Mold does not follow the humidity map
Phoenix has one of the lowest outdoor mold scores in this table (Arizona = 29/100), yet it has the third highest mold sensitization rate (19%), meaning nearly one in five allergy patients there reacts to mold. Four of the top five cities for mold sensitization are in dry climates: Dallas (21%), Riverside (20%), Phoenix (19%), and Los Angeles (17%). The dry desert cities, not the humid Southeast, have the most mold-reactive people.
That gap between dry air and high reactions points indoors. Air conditioning creates condensation inside ductwork. Evaporative coolers push moisture into indoor air. Hidden plumbing leaks grow mold behind walls. The mold people react to is often in their own homes, which is why the EPA treats mold as a household problem, not a geography problem.
Clean air can hide a wildfire problem
The PM2.5 score in this table measures year-round particle pollution. Some cities pass that measure but still get hammered by short-term smoke spikes. Seattle passes year-round PM2.5 but ranks 8th worst in the nation for short-term particle pollution. Spokane and Portland show the same pattern. If you live in the wildfire-prone West, a passing year-round grade does not mean your air is clean during fire season.
Rankings are unstable now
The 2026 AAFA report showed the biggest single-year ranking shifts in its history. These are jumps in how bad each city is for pollen, from near the bottom of the list to the top in one year. Boise went from 95th worst to 1st. San Diego went from 97th to 2nd. Salt Lake City went from 99th to 13th. On the air quality side, San Diego leapt from 59th to 5th worst for year-round particle pollution in the same span. Wet winters followed by drought produced heavier, longer pollen seasons, and the map is still moving. A city that was mild for allergies a year ago can be severe now.
What this means for you
This table is not a relocation guide. The AAFA says it directly: moving cities will not necessarily fix your allergies.
What it shows is that your inflammation load comes from multiple sources. If you live in a city with average pollen but failing air quality and high mold risk, your total load may be higher than someone in a worse pollen city with clean air and a dry home.
The good news is that you have more control over your load than the map suggests. Where you sleep is the one place you can actually change the air you breathe. A HEPA filter near the bed, allergen-proof mattress and pillow encasements, indoor humidity kept below 50 percent, and weekly hot-water laundering of bedding cut your exposure to pollen, mold, and particles alike.
This inflammation load also affects your sleep. Allergen exposure at night keeps your nose congested and your immune system active while you are trying to rest, which is a big reason people who "sleep enough" still wake up tired. If that sounds familiar, it is worth understanding what actually drives sleep quality and how breathing shapes sleep.
Frequently asked questions
What is the worst U.S. city for allergies overall in 2026?
For allergies specifically, meaning true allergens, the worst U.S. city is Rochester, New York, which scores a maximum 18 out of 18 on allergy load from worse than average pollen and the second highest state mold level in the country. If you widen the lens to total airborne inflammation load, which also counts particle pollution, San Diego and San Francisco tie for worst at 21 out of 26, because they add failing air quality on top of high pollen.
Which U.S. cities have the highest allergen load?
Ranked by allergy load, which combines pollen and outdoor mold, the two true allergens, into a score out of 18, the highest allergen load U.S. cities are Rochester, New York (18), Chicago (16), and Raleigh, North Carolina (14). These cities pair worse than average pollen with high regional mold. Air quality is not counted here, so a city can top the allergen list while still having relatively clean air, which is the case for Rochester and Raleigh.
Which U.S. cities have the highest total airborne inflammation load?
Ranked by airborne inflammation load, which combines pollen exposure, PM2.5 air quality, and outdoor mold into one score out of 26, the highest-load U.S. cities are San Diego and San Francisco (21), followed by Chicago and Salt Lake City (20), then Rochester, Austin, and Philadelphia (18). These cities rank high not because of one extreme exposure, but because two or three categories are elevated at the same time. A city can have moderate pollen and still carry a heavy inflammation load if its air quality and mold levels are both poor.
What is the difference between allergy load and inflammation load?
Allergy load counts only true allergens, pollen and mold, which trigger an IgE allergic response. Airborne inflammation load adds fine particle pollution (PM2.5) on top. Particle pollution is not an allergen, so it is not part of allergy load, but it inflames the same airways and worsens allergic reactions, so it is part of your total inflammation load. When a city's inflammation load is much higher than its allergy load, air quality is the main driver, not pollen or mold.
Can you have allergies without sneezing?
Yes. Immune reactions to mold, pollen, and particle pollution can show up as fatigue, brain fog, poor focus, and non-restorative sleep without classic symptoms like sneezing or itchy eyes. Nasal congestion alone accounts for a large share of the quality-of-life burden from allergic rhinitis, and it is often worse at night.
Why is mold worse in dry-climate cities?
Outdoor climate and indoor environment are different. In hot, dry cities, air conditioning systems create condensation inside ductwork. Evaporative coolers add moisture directly to indoor air. Hidden plumbing leaks create moisture pockets behind walls. Four of the top five U.S. cities for mold sensitization are in dry climates, not the humid Southeast.
Is Austin, Texas bad for allergies?
Austin ranks #81 on the AAFA overall ranking, but that includes healthcare access, not just pollen. Austin's actual pollen exposure is "average" by the AAFA's pollen-only measure, and in 2025 it had one of the highest counts of "high" and "very high" tree pollen days of any U.S. city. Austin also has year-round pollen from cedar in winter, oak in spring, grass in summer, and ragweed in fall. Its year-round PM2.5 jumped onto the worst 25 list, which is why its inflammation load is much higher than its allergy load. On our inflammation load score, Austin ties for #5 out of 36 cities.
What type of pollen is worst for allergies?
It depends on where you live and what you are sensitized to. Tree pollen (oak, cedar, birch, elm) dominates in spring. Grass pollen (Bermuda, Timothy, Kentucky blue) peaks late spring through summer. Weed pollen, especially ragweed, is the worst offender in late summer and fall. About 1 in 7 people are allergic to ragweed. One ragweed plant can produce billions of pollen grains that travel hundreds of miles.