Jefferson, Colorado Air Quality

Jefferson County, Colorado (CO)

→ Stableover 10 years

Air Quality Grade

46/100

Current Median AQI

Good

5-Year Avg AQI

10-Year Change

Worse

Unhealthy Days/yr

5-year average

Ozone

Primary Pollutant

Ground-Level Ozone

10-Year AQI Trend

The solid line shows the median AQI each year. The dashed line shows the 90th percentile (worst 10% of days).

Air Quality Day Breakdown

Number of days per year in each EPA AQI category. Green = Good (AQI 0-50), Yellow = Moderate (51-100), Orange = Unhealthy for Sensitive Groups (101-150), Red = Unhealthy or worse (151+).

Year-by-Year Data

Year	Median AQI	90th Pct	Max AQI	Good Days	Moderate	Unhealthy+	Pollutant
2023	49	90	143	206	141	18	Ozone
2022	47	97	166	234	100	31	Ozone
2021	47	115	172	222	88	55	Ozone
2020	46	90	161	231	108	27	Ozone
2019	46	87	129	238	111	16	Ozone
2018	46	101	151	229	99	37	Ozone
2017	47	93	136	214	123	28	Ozone
2016	46	87	159	245	101	20	Ozone
2015	45	84	164	244	104	17	Ozone
2014	46	84	140	228	121	16	Ozone

What This Means for Jefferson County Residents

Jefferson, Colorado has received an Air Quality Grade of D (46/100) based on a decade of EPA monitoring data. The current median AQI of 49 falls in the "Good" range.

The primary pollutant affecting this area is Ground-Level Ozone. Over the past 5 years, this area has averaged 29 unhealthy air quality days per year — days when sensitive groups (children, elderly, those with respiratory conditions) should limit outdoor activity.