Node / meshtastic / Meshtastic-Android / files / core / model / src / commonMain / kotlin / org / meshtastic / core / model / util / AirQualityIndex.kt

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T8b949e/*

* Copyright (c) 2026 Meshtastic LLC

*

* This program is free software: you can redistribute it and/or modify

* it under the terms of the GNU General Public License as published by

* the Free Software Foundation, either version 3 of the License, or

* (at your option) any later version.

*

* This program is distributed in the hope that it will be useful,

* but WITHOUT ANY WARRANTY; without even the implied warranty of

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

* GNU General Public License for more details.

*

* You should have received a copy of the GNU General Public License

* along with this program. If not, see <https://www.gnu.org/licenses/>.

*/

Tf0883e@fileTb4b4b4:Te6edf3SuppressTb4b4b4(Ta5d6ff"Ta5d6ffMagicNumberTa5d6ff"Tb4b4b4)

Tff7b72package T7ee787org.meshtastic.core.model.util

Tff7b72import T7ee787kotlin.math.pow

T8b949e/**

* EPA NowCast + AQI breakpoint math for PM2.5, per meshtastic/design#54.

*

* NowCast is a 12-hour rolling average of PM2.5 that weights recent hours more heavily than older ones, used in lieu of

* the official 24h EPA AQI average because it can report a value well before a full day of data exists. See

* https://usepa.servicenowservices.com/airnow (NowCast) and the EPA PM2.5 AQI breakpoint table.

*/

Tff7b72object T56d364AirQualityIndex Tb4b4b4{

Tff7b72private Tff7b72const Tff7b72val Te6edf3NOWCAST_WINDOW_HOURS Tff7b72= T79c0ff1T79c0ff2

Tff7b72private Tff7b72const Tff7b72val Te6edf3SECONDS_PER_HOUR Tff7b72= T79c0ff3T79c0ff6T79c0ff0T79c0ff0L

T8b949e/** EPA requires the most recent hour plus at least 2 of the 3 most recent hours, or NowCast isn't reported. */

Tff7b72private Tff7b72const Tff7b72val Te6edf3MIN_VALID_HOURS Tff7b72= T79c0ff2

Tff7b72private Tff7b72const Tff7b72val Te6edf3RECENT_WINDOW_HOURS Tff7b72= T79c0ff3

Tff7b72private Tff7b72const Tff7b72val Te6edf3MIN_WEIGHT_FACTOR Tff7b72= T79c0ff0.5

T8b949e/**

* Computes the NowCast PM2.5 concentration (µg/m³) from a node's PM2.5 [readings] (epoch-seconds to µg/m³ pairs),

* relative to [nowEpochSeconds]. Readings are binned into hourly buckets (0 = most recent hour) and averaged within

* each bucket. Returns null if there isn't enough history yet: the most recent hour must have a reading, and at

* least [MIN_VALID_HOURS] of the [RECENT_WINDOW_HOURS] most recent hours must be populated — EPA's minimum-data

* rule, so stale data spread across the older end of the 12h window can't produce a value.

*/

Tff7b72fun Td2a8ffcomputeNowCastPm25Tb4b4b4(Te6edf3readingsTb4b4b4: Te6edf3ListTff7b72<Te6edf3PairTff7b72<Tffa657LongTb4b4b4, Tffa657DoubleTff7b72>Tff7b72>Tb4b4b4, Te6edf3nowEpochSecondsTb4b4b4: Tffa657LongTb4b4b4)Tb4b4b4: Tffa657Double? Tb4b4b4{

Tff7b72val Te6edf3sums Tff7b72= Te6edf3DoubleArrayTb4b4b4(Te6edf3NOWCAST_WINDOW_HOURSTb4b4b4)

Tff7b72val Te6edf3counts Tff7b72= Te6edf3IntArrayTb4b4b4(Te6edf3NOWCAST_WINDOW_HOURSTb4b4b4)

Tff7b72for Tb4b4b4(Tb4b4b4(Te6edf3timeTb4b4b4, Te6edf3pm25Tb4b4b4) Tff7b72in Te6edf3readingsTb4b4b4) Tb4b4b4{

Tff7b72val Te6edf3hoursAgo Tff7b72= Tb4b4b4(Te6edf3nowEpochSeconds Tff7b72- Te6edf3timeTb4b4b4) Tff7b72/ Te6edf3SECONDS_PER_HOUR

Tff7b72if Tb4b4b4(Te6edf3hoursAgo Tff7b72in T79c0ff0 Te6edf3until Te6edf3NOWCAST_WINDOW_HOURSTb4b4b4) Tb4b4b4{

Te6edf3sumsTff7b72[Te6edf3hoursAgoTb4b4b4.Te6edf3toIntTb4b4b4(Tb4b4b4)Tff7b72] Tff7b72+Tff7b72= Te6edf3pm25

Te6edf3countsTff7b72[Te6edf3hoursAgoTb4b4b4.Te6edf3toIntTb4b4b4(Tb4b4b4)Tff7b72]Tff7b72+Tff7b72+

Tb4b4b4}

Tb4b4b4}

Tff7b72val Te6edf3hourlyAverages Tff7b72= Te6edf3ListTb4b4b4(Te6edf3NOWCAST_WINDOW_HOURSTb4b4b4) Tb4b4b4{ Te6edf3i Tff7b72-Tff7b72> Tff7b72if Tb4b4b4(Te6edf3countsTff7b72[Te6edf3iTff7b72] Tff7b72> T79c0ff0Tb4b4b4) Te6edf3sumsTff7b72[Te6edf3iTff7b72] Tff7b72/ Te6edf3countsTff7b72[Te6edf3iTff7b72] Tff7b72else Tff7b72null Tb4b4b4}

Tff7b72val Te6edf3present Tff7b72= Te6edf3hourlyAveragesTb4b4b4.Te6edf3withIndexTb4b4b4(Tb4b4b4)Tb4b4b4.Te6edf3mapNotNull Tb4b4b4{ Tb4b4b4(Te6edf3iTb4b4b4, Te6edf3vTb4b4b4) Tff7b72-Tff7b72> Te6edf3vTff7b72?.Te6edf3let Tb4b4b4{ Te6edf3i Te6edf3to Tffa657it Tb4b4b4} Tb4b4b4}

Tff7b72val Te6edf3recentValid Tff7b72= Te6edf3hourlyAveragesTb4b4b4.Te6edf3takeTb4b4b4(Te6edf3RECENT_WINDOW_HOURSTb4b4b4)Tb4b4b4.Te6edf3count Tb4b4b4{ Tffa657it Tff7b72!Tff7b72= Tff7b72null Tb4b4b4}

Tff7b72return Tff7b72if Tb4b4b4(Te6edf3hourlyAveragesTff7b72[T79c0ff0Tff7b72] Tff7b72=Tff7b72= Tff7b72null Tff7b72|Tff7b72| Te6edf3recentValid Tff7b72< Te6edf3MIN_VALID_HOURSTb4b4b4) Tb4b4b4{

Tff7b72null

Tb4b4b4} Tff7b72else Tb4b4b4{

Tff7b72val Te6edf3max Tff7b72= Te6edf3presentTb4b4b4.Te6edf3maxOf Tb4b4b4{ Tffa657itTb4b4b4.Te6edf3second Tb4b4b4}

Tff7b72val Te6edf3min Tff7b72= Te6edf3presentTb4b4b4.Te6edf3minOf Tb4b4b4{ Tffa657itTb4b4b4.Te6edf3second Tb4b4b4}

Tff7b72val Te6edf3weightFactor Tff7b72= Tff7b72if Tb4b4b4(Te6edf3max Tff7b72<Tff7b72= T79c0ff0.0Tb4b4b4) T79c0ff1.0 Tff7b72else Tb4b4b4(T79c0ff1.0 Tff7b72- Tb4b4b4(Te6edf3max Tff7b72- Te6edf3minTb4b4b4) Tff7b72/ Te6edf3maxTb4b4b4)Tb4b4b4.Te6edf3coerceAtLeastTb4b4b4(Te6edf3MIN_WEIGHT_FACTORTb4b4b4)

Tff7b72var Te6edf3weightedSum Tff7b72= T79c0ff0.0

Tff7b72var Te6edf3weightTotal Tff7b72= T79c0ff0.0

Tff7b72for Tb4b4b4(Tb4b4b4(Te6edf3hoursAgoTb4b4b4, Te6edf3valueTb4b4b4) Tff7b72in Te6edf3presentTb4b4b4) Tb4b4b4{

Tff7b72val Te6edf3weight Tff7b72= Te6edf3weightFactorTb4b4b4.Te6edf3powTb4b4b4(Te6edf3hoursAgoTb4b4b4)

Te6edf3weightedSum Tff7b72+Tff7b72= Te6edf3weight Tff7b72* Te6edf3value

Te6edf3weightTotal Tff7b72+Tff7b72= Te6edf3weight

Tb4b4b4}

Te6edf3weightedSum Tff7b72/ Te6edf3weightTotal

Tb4b4b4}

Tb4b4b4}

T8b949e/**

* The historical NowCast AQI for every reading in [readings] — element `i` is the AQI as of `readings[i]`'s own

* timestamp, derived only from readings at or before it, or null where EPA's minimum-data rule (see

* [computeNowCastPm25]) isn't met at that point. Used to chart/tabulate AQI over time (issue #6381) rather than

* only the single live value.

*

* [readings] must be sorted ascending by epoch-second timestamp; a sliding window keeps this linear in the number

* of readings per 12-hour window rather than quadratic over the whole time frame.

*/

Tff7b72fun Td2a8ffnowCastAqiSeriesTb4b4b4(Te6edf3readingsTb4b4b4: Te6edf3ListTff7b72<Te6edf3PairTff7b72<Tffa657LongTb4b4b4, Tffa657DoubleTff7b72>Tff7b72>Tb4b4b4)Tb4b4b4: Te6edf3ListTff7b72<Tffa657Int?Tff7b72> Tb4b4b4{

Tff7b72val Te6edf3windowSeconds Tff7b72= Te6edf3NOWCAST_WINDOW_HOURS Tff7b72* Te6edf3SECONDS_PER_HOUR

Tff7b72var Te6edf3start Tff7b72= T79c0ff0

Tff7b72return Te6edf3readingsTb4b4b4.Te6edf3mapIndexed Tb4b4b4{ Te6edf3indexTb4b4b4, Tb4b4b4(Te6edf3timeTb4b4b4, Te6edf3_Tb4b4b4) Tff7b72-Tff7b72>

T8b949e// Readings at or before this cutoff fall outside the point's own 12h window, so drop them from the front.

Tff7b72val Te6edf3cutoff Tff7b72= Te6edf3time Tff7b72- Te6edf3windowSeconds

Tff7b72while Tb4b4b4(Te6edf3readingsTff7b72[Te6edf3startTff7b72]Tb4b4b4.Te6edf3first Tff7b72<Tff7b72= Te6edf3cutoffTb4b4b4) Te6edf3startTff7b72+Tff7b72+

Te6edf3computeNowCastPm25Tb4b4b4(Te6edf3readingsTb4b4b4.Te6edf3subListTb4b4b4(Te6edf3startTb4b4b4, Te6edf3index Tff7b72+ T79c0ff1Tb4b4b4)Tb4b4b4, Te6edf3timeTb4b4b4)Tff7b72?.Te6edf3letTb4b4b4(Tff7b72::Te6edf3pm25ToAqiTb4b4b4)

Tb4b4b4}

Tb4b4b4}

Tff7b72private Tff7b72data Tff7b72class T56d364BreakpointTb4b4b4(

Tff7b72val Te6edf3concentrationLowTb4b4b4: Tffa657DoubleTb4b4b4,

Tff7b72val Te6edf3concentrationHighTb4b4b4: Tffa657DoubleTb4b4b4,

Tff7b72val Te6edf3aqiLowTb4b4b4: Tffa657IntTb4b4b4,

Tff7b72val Te6edf3aqiHighTb4b4b4: Tffa657IntTb4b4b4,

Tb4b4b4)

T8b949e// Current (2024) EPA PM2.5 24-hour breakpoint table (AQS parameter 88101), µg/m³.

T8b949e// Kept in lockstep with iOS (meshtastic/Meshtastic-Apple#2075) for cross-platform AQI alignment

T8b949e// (meshtastic/design#54).

Tff7b72private Tff7b72val Te6edf3BREAKPOINTS Tff7b72=

Te6edf3listOfTb4b4b4(

Te6edf3BreakpointTb4b4b4(T79c0ff0.0Tb4b4b4, T79c0ff9.0Tb4b4b4, T79c0ff0Tb4b4b4, T79c0ff5T79c0ff0Tb4b4b4)Tb4b4b4,

Te6edf3BreakpointTb4b4b4(T79c0ff9.1Tb4b4b4, T79c0ff3T79c0ff5.4Tb4b4b4, T79c0ff5T79c0ff1Tb4b4b4, T79c0ff1T79c0ff0T79c0ff0Tb4b4b4)Tb4b4b4,

Te6edf3BreakpointTb4b4b4(T79c0ff3T79c0ff5.5Tb4b4b4, T79c0ff5T79c0ff5.4Tb4b4b4, T79c0ff1T79c0ff0T79c0ff1Tb4b4b4, T79c0ff1T79c0ff5T79c0ff0Tb4b4b4)Tb4b4b4,

Te6edf3BreakpointTb4b4b4(T79c0ff5T79c0ff5.5Tb4b4b4, T79c0ff1T79c0ff2T79c0ff5.4Tb4b4b4, T79c0ff1T79c0ff5T79c0ff1Tb4b4b4, T79c0ff2T79c0ff0T79c0ff0Tb4b4b4)Tb4b4b4,

Te6edf3BreakpointTb4b4b4(T79c0ff1T79c0ff2T79c0ff5.5Tb4b4b4, T79c0ff2T79c0ff2T79c0ff5.4Tb4b4b4, T79c0ff2T79c0ff0T79c0ff1Tb4b4b4, T79c0ff3T79c0ff0T79c0ff0Tb4b4b4)Tb4b4b4,

Te6edf3BreakpointTb4b4b4(T79c0ff2T79c0ff2T79c0ff5.5Tb4b4b4, T79c0ff3T79c0ff2T79c0ff5.4Tb4b4b4, T79c0ff3T79c0ff0T79c0ff1Tb4b4b4, T79c0ff5T79c0ff0T79c0ff0Tb4b4b4)Tb4b4b4,

Tb4b4b4)

T8b949e/**

* Converts a PM2.5 concentration (µg/m³) to a 0-500 EPA AQI value via linear interpolation over the standard

* breakpoint table. Concentrations above the top breakpoint are clamped to AQI 500.

*/

Tff7b72fun Td2a8ffpm25ToAqiTb4b4b4(Te6edf3concentrationTb4b4b4: Tffa657DoubleTb4b4b4)Tb4b4b4: Tffa657Int Tb4b4b4{

Tff7b72val Te6edf3clamped Tff7b72= Te6edf3concentrationTb4b4b4.Te6edf3coerceAtLeastTb4b4b4(T79c0ff0.0Tb4b4b4)

Tff7b72val Te6edf3breakpoint Tff7b72= Te6edf3BREAKPOINTSTb4b4b4.Te6edf3lastOrNull Tb4b4b4{ Te6edf3clamped Tff7b72>Tff7b72= Tffa657itTb4b4b4.Te6edf3concentrationLow Tb4b4b4} Tff7b72?: Te6edf3BREAKPOINTSTb4b4b4.Te6edf3firstTb4b4b4(Tb4b4b4)

Tff7b72if Tb4b4b4(Te6edf3clamped Tff7b72> Te6edf3breakpointTb4b4b4.Te6edf3concentrationHighTb4b4b4) Tff7b72return Te6edf3breakpointTb4b4b4.Te6edf3aqiHigh

Tff7b72val Te6edf3aqi Tff7b72=

Tb4b4b4(Te6edf3breakpointTb4b4b4.Te6edf3aqiHigh Tff7b72- Te6edf3breakpointTb4b4b4.Te6edf3aqiLowTb4b4b4)Tb4b4b4.Te6edf3toDoubleTb4b4b4(Tb4b4b4) Tff7b72/

Tb4b4b4(Te6edf3breakpointTb4b4b4.Te6edf3concentrationHigh Tff7b72- Te6edf3breakpointTb4b4b4.Te6edf3concentrationLowTb4b4b4) Tff7b72* Tb4b4b4(Te6edf3clamped Tff7b72- Te6edf3breakpointTb4b4b4.Te6edf3concentrationLowTb4b4b4) Tff7b72+

Te6edf3breakpointTb4b4b4.Te6edf3aqiLow

Tff7b72return Te6edf3aqiTb4b4b4.Te6edf3let Tb4b4b4{ Te6edf3kotlinTb4b4b4.Te6edf3mathTb4b4b4.Te6edf3roundTb4b4b4(Tffa657itTb4b4b4)Tb4b4b4.Te6edf3toIntTb4b4b4(Tb4b4b4) Tb4b4b4}

Tb4b4b4}

Tb4b4b4}