Tools in This Collection
Air Quality Index (AQI) Reference
Understand the 0-500 AQI scale with health effects and outdoor activity guidance at each level
UV Index by City
Look up average monthly UV intensity for 30+ major US cities to plan safe outdoor activities
Allergy Season Calendar
Find tree, grass, weed, and mold pollen seasons by US region for allergy planning
Flu Season Timeline
Find peak flu weeks by US region and optimal flu vaccination timing
Hearing Protection Calculator
Calculate the NRR needed to protect hearing at your noise exposure level using OSHA derating
Fitzpatrick Skin Type Quiz
Determine your Fitzpatrick skin type (I-VI) for personalized UV protection and vitamin D guidance
Guides & Articles
Environmental Health Workflow
Your environment is a significant determinant of health, and several environmental factors have measurable thresholds that require behavioral responses. Understanding air quality, UV exposure, seasonal allergen patterns, and noise exposure helps you make informed decisions about outdoor activities, timing, and protective equipment. These tools are for informational purposes only. Consult your healthcare provider for medical guidance specific to your health conditions.
Air Quality: When to Modify Outdoor Activity
The AQI scale runs from 0 (clean) to 500 (hazardous). The 6 categories define health risk levels: Good (0-50), Moderate (51-100), Unhealthy for Sensitive Groups (101-150), Unhealthy (151-200), Very Unhealthy (201-300), Hazardous (301+). For healthy adults, outdoor exercise is generally safe through Moderate (100). At Unhealthy for Sensitive Groups (101-150), people with asthma, heart disease, or lung conditions should reduce outdoor exertion. Above 150, outdoor strenuous exercise is not recommended for anyone.
UV Exposure: Balancing Protection and Vitamin D Synthesis
UV radiation follows a strong seasonal and geographic pattern. The UV Index by City tool shows historical monthly averages for major US cities — useful for planning outdoor activities and understanding when SPF protection is most critical. UV index above 8 requires protective clothing and sunscreen for all skin types. The Fitzpatrick Skin Type Quiz identifies your personal UV sensitivity, which informs how quickly you burn and how much sun exposure is needed for adequate vitamin D synthesis.
Seasonal Planning: Allergies and Flu
Tree pollen season peaks in spring (March-May), grass pollen in late spring/early summer (May-July), and weed pollen in late summer/fall (August-October). Timing varies by 2-4 weeks across US regions. The Allergy Season Calendar maps these patterns by region. For flu, the Flu Season Timeline shows when to get vaccinated (ideally by October) and when peak transmission historically occurs in each US region.
Frequently Asked Questions
What AQI level should I avoid outdoor exercise?
For healthy adults: outdoor exercise is safe at AQI 0-100. At AQI 101-150, sensitive groups (asthma, heart disease, lung conditions) should reduce intensity or exercise indoors. Above AQI 150, all outdoor strenuous exercise should be avoided. If you're exercising outdoors and smell smoke or feel eye/throat irritation, check the current AQI — it may have risen since you started.
What UV index requires sunscreen?
UV index 3+ requires sun protection for fair-skinned individuals. UV index 6+ requires sunscreen (SPF 30+), protective clothing, and shade for all skin types during peak hours (10am-4pm). UV index 11+ is extreme — all outdoor exposure should involve full sun protection. Summer UV index in the southern US regularly reaches 10-12.
When is allergy season in the US?
Allergy seasons: tree pollen peaks March-May (varies by region, earlier in the South), grass pollen peaks May-July, weed (ragweed) pollen peaks August-October. Mold spores peak in late summer and fall. Total pollen exposure is highest in the South and Southeast. The Allergy Season Calendar shows regional patterns by allergen type.
How much noise exposure is dangerous to hearing?
OSHA's permissible noise exposure limit is 90 dB for 8 hours per day. Each 5 dB increase halves the allowable exposure time: 95 dB is safe for 4 hours, 100 dB for 2 hours. At 110 dB (concerts, power tools), safe exposure is under 30 minutes. The Hearing Protection Calculator determines what NRR earplug or earmuff rating you need to get below safe exposure thresholds.
What is the Fitzpatrick skin type scale?
The Fitzpatrick scale classifies skin into 6 types based on pigmentation and response to UV exposure: Type I (always burns, never tans) through Type VI (never burns, deeply pigmented). Types I-II require the most UV protection and reach vitamin D synthesis thresholds from less sun exposure. Types V-VI need more sun exposure for the same vitamin D production. The Skin Type Quiz walks through identifying factors.