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Merge pull request #226 from airgradienthq/fix/pm2.5-compensated-formula

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Fix pm2.5 compensation formula
This commit is contained in:
AirGradient
2024-09-02 12:06:39 +07:00
committed by GitHub
parent 228bf83e92 aafaa42a68
commit 02b63ff816
1 changed files with 14 additions and 11 deletions
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25
src/PMS/PMS.cpp
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@ -309,29 +309,32 @@ int PMSBase::pm25ToAQI(int pm02) {
/**
* @brief Correction PM2.5
*
* Formula: https://www.airgradient.com/documentation/correction-algorithms/
*
* @param pm25 Raw PM2.5 value
* @param humidity Humidity value (%)
* @return int
*/
int PMSBase::compensated(int pm25, float humidity) {
float value;
float fpm25 = pm25;
if (humidity < 0) {
humidity = 0;
}
if (humidity > 100) {
humidity = 100;
humidity = 100.0f;
}
if(pm25 < 30) {
value = (pm25 * 0.524f) - (humidity * 0.0862f) + 5.75f;
} else if(pm25 < 50) {
value = (0.786f * (pm25 / 20 - 3 / 2) + 0.524f * (1 - (pm25 / 20 - 3 / 2))) * pm25 - (0.0862f * humidity) + 5.75f;
} else if(pm25 < 210) {
value = (0.786f * pm25) - (0.0862f * humidity) + 5.75f;
} else if(pm25 < 260) {
value = (0.69f * (pm25/50 - 21/5) + 0.786f * (1 - (pm25/50 - 21/5))) * pm25 - (0.0862f * humidity * (1 - (pm25/50 - 21/5))) + (2.966f * (pm25/50 -21/5)) + (5.75f * (1 - (pm25/50 - 21/5))) + (8.84f * (1.e-4) * pm25* (pm25/50 - 21/5));
} else {
value = 2.966f + (0.69f * pm25) + (8.84f * (1.e-4) * pm25);
if(pm25 < 30) { /** pm2.5 < 30 */
value = (fpm25 * 0.524f) - (humidity * 0.0862f) + 5.75f;
} else if(pm25 < 50) { /** 30 <= pm2.5 < 50 */
value = (0.786f * (fpm25 * 0.05f - 1.5f) + 0.524f * (1.0f - (fpm25 * 0.05f - 1.5f))) * fpm25 - (0.0862f * humidity) + 5.75f;
} else if(pm25 < 210) { /** 50 <= pm2.5 < 210 */
value = (0.786f * fpm25) - (0.0862f * humidity) + 5.75f;
} else if(pm25 < 260) { /** 210 <= pm2.5 < 260 */
value = (0.69f * (fpm25 * 0.02f - 4.2f) + 0.786f * (1.0f - (fpm25 * 0.02f - 4.2f))) * fpm25 - (0.0862f * humidity * (1.0f - (fpm25 * 0.02f - 4.2f))) + (2.966f * (fpm25 * 0.02f - 4.2f)) + (5.75f * (1.0f - (fpm25 * 0.02f - 4.2f))) + (8.84f * (1.e-4) * fpm25 * fpm25 * (fpm25 * 0.02f - 4.2f));
} else { /** 260 <= pm2.5 */
value = 2.966f + (0.69f * fpm25) + (8.84f * (1.e-4) * fpm25 * fpm25);
}
if(value < 0) {