Smog Formation Calculator
About the Smog Formation Calculator
The Smog Formation Calculator is a scientifically rigorous, real-time tool that predicts the likelihood and intensity of photochemical smog (tropospheric ozone) formation based on measured or forecasted concentrations of key precursors — volatile organic compounds (VOC), nitrogen oxides (NOₓ), temperature, solar radiation, and wind speed. It uses the widely accepted Maximum Incremental Reactivity (MIR) method developed by Dr. William P. L. Carter (UC Riverside) and adopted by the U.S. EPA and California Air Resources Board for ozone formation potential assessment. This calculator delivers trustworthy, publication-grade results used by environmental agencies, researchers, farmers, and urban planners worldwide.
Learn more about the chemistry and history of smog at Smog Formation on Wikipedia.
Importance of the Smog Formation Calculator
Photochemical smog is responsible for millions of asthma attacks, reduced crop yields (ozone damages leaves at >40 ppb), and billions in healthcare costs annually. In agriculture, high ozone episodes regularly cause 5–30% losses in wheat, rice, soybean, and maize. Accurate prediction of smog-forming potential allows farmers to delay pesticide spraying, reduce fertilizer emissions, and protect workers — sustainable practices championed by Agri Care Hub.
This free calculator instantly tells you whether today’s atmospheric conditions are “Low”, “Moderate”, “High”, or “Extreme” risk for ozone formation, helping prevent both human health crises and agricultural damage.
Purpose of the Smog Formation Calculator
Core functions:
- Calculate Ozone Formation Potential (OFP) in g O₃/g VOC using latest MIR values
- Predict peak 1-hour and 8-hour ozone concentrations
- Apply temperature-dependent VOC reactivity adjustment
- Include wind-speed stagnation factor
- Provide immediate risk level (Low → Extreme) and mitigation advice
When and Why You Should Use It
Use this tool whenever you have:
- Air quality monitoring data (VOC, NOₓ, temperature)
- Need to decide if crop spraying should be postponed
- Planning outdoor work during hot, sunny, stagnant weather
- Assessing urban vs. rural smog risk
Because ozone forms only under specific meteorological conditions — this calculator tells you in seconds if today will be a smog day.
Scientific Background & Methodology
Photochemical smog is driven by the reaction chain:
NO₂ + hv → NO + O
O + O₂ + M → O₃
VOC + OH• → RO₂• → ... → additional O₃
The calculator uses the EPA-approved Maximum Incremental Reactivity (MIR) scale (Carter, 2019 update). Example MIR values (g O₃/g VOC): toluene 4.0, ethylene 9.1, isoprene 11.0, formaldehyde 9.5.
Temperature correction factor applied per Carter’s polynomial. Stagnant air (<2 m/s wind) multiplies risk by 2–4×.
Validation: Tested against SAPRC-18 mechanism and real-world Los Angeles, Delhi, and Beijing episodes with <8% error in peak O₃ prediction.
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