Franklin County, Maine air quality history

Daily Air Quality Index summaries from EPA monitors in Franklin, Maine, 1981–2017.

83%

Good days in 2017

Median daily AQI, 2017

Days above 100 in 2017

242

Days with an AQI in 2017 (of 365)

In 2017, EPA reported a daily Air Quality Index (AQI) for Franklin, Maine on 242 days. 202 of those days (83%) were in the Good range, and the median daily AQI was 27. That median is lower than the typical monitored county in Maine (median 37 across 11 counties), and lower than the typical monitored U.S. county (41). The main pollutant was fine particles (PM2.5) on 242 days. Across the years with fuller monitoring, the share of Good days fell: an average of 97% in 1981–1986 versus 91% in 1998–2017.

EPA did not report an AQI for every day of 2017 here (242 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

The most recent year with data for this county is 2017; EPA's files for 2018–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2000, 2001, 2002, 2003, 2004, 2015…) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median daily AQI
90th-percentile daily AQI

Main pollutant by day, 2017

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

Pollutant	Days as main pollutant	Share of monitored days
Fine particles (PM2.5)	242	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Unhealthy for Sensitive Groups	Unhealthy	Median AQI	90th pct.	Max AQI	Main pollutant
2017	242	202	40	0	0	27	54	75	PM2.5
2016	347	313	34	0	0	21	48	72	PM2.5
2015	49	48	1	0	0	11	26	51	PM2.5
2004	61	61	0	0	0	11	19	31	PM10
2003	61	61	0	0	0	12	23	44	PM10
2002	61	61	0	0	0	9	18	36	PM10
2001	61	61	0	0	0	10	21	40	PM10
2000	61	61	0	0	0	9	19	28	PM10
1999	80	80	0	0	0	12	21	44	PM10
1998	120	119	1	0	0	11	23	53	PM10
1997	122	122	0	0	0	12	20	31	PM10
1996	121	121	0	0	0	12	22	43	PM10
1995	121	120	1	0	0	12	23	52	PM10
1994	123	123	0	0	0	13	27	42	PM10
1993	137	137	0	0	0	14	27	40	PM10
1992	183	181	2	0	0	14	26	57	PM10
1991	181	180	1	0	0	16	31	52	PM10
1990	182	182	0	0	0	17	31	48	PM10
1989	152	149	3	0	0	18	35	57	PM10
1988	163	159	4	0	0	18	34	60	PM10
1987	211	169	29	12	1	32	71	154	Ozone
1986	184	169	11	4	0	28	48	122	Ozone
1985	86	84	2	0	0	15	37	55	PM10
1982	228	228	0	0	0	3	5	6	CO
1981	125	125	0	0	0	5	7	10	CO

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

All monitored counties in Maine

Source: U.S. EPA AirData, “Annual AQI by County” files for 1981–2017 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem