Bad Air Days in Greene County, Pennsylvania: under 1 a Year

under 1 bad air day a year

Rare: among the cleanest-air counties EPA monitors. Ranked 764 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (17% particle days).

Which months to watch

Most bad days here fall in April and July and May and June. Averaged over 2016 to 2025.

What actually helps here

Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
On the odd bad day, check AirNow and keep windows shut.

The worst days on file

In 2000 to 2009 this county averaged 35 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2023, with 2 bad days on 302 monitored days.

Date	AQI	Main pollutant
2021-07-20	113	PM2.5
2023-04-13	108	Ozone
2016-04-17	105	Ozone
2023-06-02	105	Ozone
2025-05-11	105	Ozone

An ordinary day in Greene

Across 3,310 monitored days from 2016 to 2025, the air in Greene County rated Good on 78% of them, more often than the 72% typical of monitored counties, and Moderate on 22%. The median day sat at AQI 40; one day in ten went above 57.

The pollutant setting the AQI on an ordinary day here:

ozone58%1,923 days
fine particles (PM2.5)42%1,387 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Median AQI	Highest AQI
2025*	365	284	80	1	40	105
2024	230	196	34	0	38	87
2023	302	219	81	2	44	108
2022	294	231	63	0	42	100
2021	340	232	107	1	42	113
2020	359	294	64	1	39	101
2019	349	294	55	0	38	71
2018	360	288	72	0	39	100
2017	356	255	101	0	42	93
2016	355	297	57	1	39	105
2015	362	301	57	4	37	115
2014	362	327	33	2	39	108
2013	340	305	33	2	38	126
2012	259	181	65	13	42	143
2011	214	175	38	1	42	112
2010	213	146	58	9	45	150

*2025 may be a partial year in EPA's file.

Nearby counties on file

How this is counted

A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day, and on why a purifier does not touch ozone in smoke vs ozone.