Bad Air Days in Nassau County, Florida: 0 a Year

0 bad air days a year

Rare: among the cleanest-air counties EPA monitors. Ranked 958 of 996 monitored counties, where 1 is worst.

What to buy, and what not to

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 2 bad days a year; in 2016 to 2025, 0. The air has improved.

Date	AQI	Main pollutant
2017-04-25	93	PM2.5
2016-11-17	86	PM2.5
2016-11-18	86	PM2.5
2018-01-20	86	PM2.5
2017-04-24	85	PM2.5

An ordinary day in Nassau

Across 1,105 monitored days from 2016 to 2020, the air in Nassau County rated Good on 67% of them, less often than the 72% typical of monitored counties, and Moderate on 33%. The median day sat at AQI 44; one day in ten went above 57.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)100%1,105 days

Nassau County by year

Year	Days monitored	Good	Moderate	Median AQI	Highest AQI
2020	43	35	8	42	57
2019	270	203	67	41	74
2018	271	192	79	43	86
2017	278	160	118	47	93
2016	243	155	88	45	86
2015	344	238	106	43	71
2014	266	142	124	48	74
2013	349	234	115	43	72

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.