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Pollen Season & Air Quality

While pollen is not measured in the EPA's Air Quality Index, it significantly impacts respiratory health and compounds the effects of traditional air pollutants. Understanding pollen seasons is essential for complete air quality awareness.

Important Note

Pollen is not included in EPA's AQI because it's a biological allergen, not a pollutant. However, high pollen combined with poor AQI creates compounded respiratory stress. This guide helps you understand both factors together.

Annual Pollen Calendar

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Tree Pollen: March-May

Peak Impact

Oak, maple, birch, cedar trees release massive pollen clouds. Worst in April. Can see yellow dusting on cars and surfaces.

Affected Regions

Nationwide issue. Southeast (pine) and Northeast (birch, oak) particularly severe. Mountain states have shorter but intense seasons.

Health Impact: Sneezing, runny nose, itchy eyes, sinus congestion, asthma triggers

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Grass Pollen: May-July

Peak Impact

Timothy, ryegrass, Bermuda grass peak in late spring/early summer. Mowing lawns releases surges of pollen.

Affected Regions

Midwest and agricultural areas worst. Southern lawns (Bermuda grass) peak earlier. Northern grasses peak June-July.

Health Impact: Respiratory irritation, compounded by early summer ozone in some areas

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Weed Pollen: August-October

Peak Impact

Ragweed dominates - one plant produces 1 billion pollen grains. Peak in September. Most allergenic of all pollens.

Affected Regions

Midwest and East Coast worst. Ragweed pollen can travel 400+ miles on wind. Less severe in West.

Health Impact: Severe allergies, asthma exacerbations, overlaps with back-to-school illnesses

Pollen + AQI Combined Effects

Double Burden Days

High pollen + poor AQI creates compounded respiratory stress worse than either alone.

• Inflamed airways from pollen more vulnerable to PM2.5
• Ozone sensitivity increases during allergy season
• Asthma attacks more severe with both factors
• Recovery time longer when exposed to both

Protection Strategies

• Check both pollen count and AQI before outdoor plans
• Avoid mornings (peak pollen) AND afternoons (peak ozone) in spring/summer
• HEPA filters capture both pollen and PM2.5 indoors
• Shower after outdoor time removes both allergens and particles
• Medications: antihistamines for pollen + monitor AQI alerts

Regional Pollen Patterns

Southeast

Worst Months: March-April (Pine), Sept (Ragweed)

Details: Year-round growing season means longer pollen exposure. High humidity can trap pollen.

Northeast

Worst Months: April-May (Tree), Sept (Ragweed)

Details: Classic spring allergies severe. Fall ragweed season intense. Winter provides relief.

Midwest

Worst Months: May-June (Grass), Aug-Sept (Ragweed)

Details: Agricultural areas see high grass pollen. Ragweed epicenter of North America.

Southwest

Worst Months: Feb-April (Trees), Spring (Grasses)

Details: Desert plants produce unique allergens. Dry air can keep pollen airborne longer.

West Coast

Worst Months: March-May (Tree)

Details: Shorter, milder pollen seasons. Mediterranean climate limits some allergens.

Mountain West

Worst Months: May-June (brief but intense)

Details: Short growing season concentrates pollen release. High altitude areas have less pollen.

Best & Worst Months for Allergy Sufferers

Best Months (Lowest Pollen)

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October-November
After first frost kills ragweed, before winter allergens
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December-February
Dormant plants, excellent for allergy relief
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After Heavy Rain
Pollen washed from air temporarily

Worst Months (Peak Pollen)

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April
Tree pollen explosion, multiple species overlap
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May
Grass pollen starts as tree pollen continues
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September
Peak ragweed season, most allergenic pollen

Daily Pollen Patterns

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5-10 AM

Pollen release peaks

Worst time

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10 AM-3 PM

Pollen peak in air

Poor

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3-8 PM

Settling begins

Moderate

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8 PM-5 AM

Lowest counts

Best time

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