EnviroNearby

Nassau County, New York air quality history

Daily Air Quality Index summaries from EPA monitors in Nassau, New York, 1980–2025.

79%
Good days in 2025
29
Median daily AQI, 2025
0
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Nassau, New York on 364 days. 287 of those days (79%) were in the Good range, and the median daily AQI was 29. That median is lower than the typical monitored county in New York (median 36 across 27 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 364 days. Across the years with fuller monitoring, the share of Good days rose: an average of 62% in 1980–1982 versus 79% in 2023–2025.

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.

Share of monitored days in each AQI category, by year0%25%50%75%100%1980: Good 210 of 365 days1980: Moderate 108 of 365 days1980: Unhealthy for Sensitive Groups 16 of 365 days1980: Unhealthy 17 of 365 days1980: Very Unhealthy 14 of 365 days19801981: Good 231 of 365 days1981: Moderate 116 of 365 days1981: Unhealthy for Sensitive Groups 16 of 365 days1981: Unhealthy 2 of 365 days1982: Good 241 of 365 days1982: Moderate 108 of 365 days1982: Unhealthy for Sensitive Groups 16 of 365 days1983: Good 205 of 365 days1983: Moderate 135 of 365 days1983: Unhealthy for Sensitive Groups 24 of 365 days1983: Unhealthy 1 of 365 days1984: Good 171 of 366 days1984: Moderate 175 of 366 days1984: Unhealthy for Sensitive Groups 20 of 366 days1985: Good 222 of 363 days1985: Moderate 133 of 363 days1985: Unhealthy for Sensitive Groups 8 of 363 days19851986: Good 286 of 365 days1986: Moderate 74 of 365 days1986: Unhealthy for Sensitive Groups 5 of 365 days1987: Good 207 of 365 days1987: Moderate 146 of 365 days1987: Unhealthy for Sensitive Groups 12 of 365 days1988: Good 185 of 337 days1988: Moderate 139 of 337 days1988: Unhealthy for Sensitive Groups 13 of 337 days1989: Good 182 of 276 days1989: Moderate 91 of 276 days1989: Unhealthy for Sensitive Groups 3 of 276 days1990: Good 255 of 365 days1990: Moderate 106 of 365 days1990: Unhealthy for Sensitive Groups 4 of 365 days19901991: Good 237 of 365 days1991: Moderate 124 of 365 days1991: Unhealthy for Sensitive Groups 4 of 365 days1992: Good 315 of 366 days1992: Moderate 50 of 366 days1992: Unhealthy for Sensitive Groups 1 of 366 days1993: Good 302 of 365 days1993: Moderate 60 of 365 days1993: Unhealthy for Sensitive Groups 3 of 365 days1994: Good 264 of 365 days1994: Moderate 96 of 365 days1994: Unhealthy for Sensitive Groups 5 of 365 days1995: Good 314 of 365 days1995: Moderate 50 of 365 days1995: Unhealthy for Sensitive Groups 1 of 365 days19951996: Good 308 of 366 days1996: Moderate 58 of 366 days1997: Good 309 of 365 days1997: Moderate 54 of 365 days1997: Unhealthy for Sensitive Groups 2 of 365 days1998: Good 333 of 365 days1998: Moderate 31 of 365 days1998: Unhealthy for Sensitive Groups 1 of 365 days1999: Good 269 of 365 days1999: Moderate 95 of 365 days1999: Unhealthy for Sensitive Groups 1 of 365 days2000: Good 258 of 358 days2000: Moderate 97 of 358 days2000: Unhealthy for Sensitive Groups 3 of 358 days20002001: Good 235 of 344 days2001: Moderate 107 of 344 days2001: Unhealthy for Sensitive Groups 2 of 344 days2002: Good 265 of 359 days2002: Moderate 92 of 359 days2002: Unhealthy for Sensitive Groups 1 of 359 days2002: Unhealthy 1 of 359 days2003: Good 241 of 322 days2003: Moderate 77 of 322 days2003: Unhealthy for Sensitive Groups 4 of 322 days2004: Good 224 of 294 days2004: Moderate 68 of 294 days2004: Unhealthy for Sensitive Groups 2 of 294 days2005: Good 261 of 339 days2005: Moderate 76 of 339 days2005: Unhealthy for Sensitive Groups 2 of 339 days20052006: Good 279 of 348 days2006: Moderate 68 of 348 days2006: Unhealthy for Sensitive Groups 1 of 348 days2007: Good 169 of 364 days2007: Moderate 191 of 364 days2007: Unhealthy for Sensitive Groups 4 of 364 days2008: Good 152 of 366 days2008: Moderate 212 of 366 days2008: Unhealthy for Sensitive Groups 2 of 366 days2009: Good 205 of 365 days2009: Moderate 159 of 365 days2009: Unhealthy for Sensitive Groups 1 of 365 days2010: Good 209 of 365 days2010: Moderate 156 of 365 days20102011: Good 159 of 343 days2011: Moderate 182 of 343 days2011: Unhealthy for Sensitive Groups 2 of 343 days2012: Good 180 of 334 days2012: Moderate 154 of 334 days2013: Good 220 of 356 days2013: Moderate 136 of 356 days2014: Good 260 of 359 days2014: Moderate 99 of 359 days2015: Good 256 of 362 days2015: Moderate 106 of 362 days20152016: Good 278 of 355 days2016: Moderate 77 of 355 days2017: Good 277 of 347 days2017: Moderate 70 of 347 days2018: Good 305 of 365 days2018: Moderate 60 of 365 days2019: Good 308 of 360 days2019: Moderate 52 of 360 days2020: Good 317 of 361 days2020: Moderate 44 of 361 days20202021: Good 291 of 360 days2021: Moderate 68 of 360 days2021: Unhealthy for Sensitive Groups 1 of 360 days2022: Good 303 of 361 days2022: Moderate 58 of 361 days2023: Good 275 of 365 days2023: Moderate 86 of 365 days2023: Unhealthy for Sensitive Groups 1 of 365 days2023: Unhealthy 3 of 365 days2024: Good 308 of 366 days2024: Moderate 58 of 366 days2025: Good 287 of 364 days2025: Moderate 77 of 364 days2025
  • 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 and 90th-percentile daily AQI, by year0501001501980: 90th percentile AQI 1261981: 90th percentile AQI 791982: 90th percentile AQI 831983: 90th percentile AQI 951984: 90th percentile AQI 911985: 90th percentile AQI 721986: 90th percentile AQI 611987: 90th percentile AQI 771988: 90th percentile AQI 771989: 90th percentile AQI 721990: 90th percentile AQI 681991: 90th percentile AQI 731992: 90th percentile AQI 541993: 90th percentile AQI 581994: 90th percentile AQI 631995: 90th percentile AQI 531996: 90th percentile AQI 561997: 90th percentile AQI 541998: 90th percentile AQI 501999: 90th percentile AQI 622000: 90th percentile AQI 662001: 90th percentile AQI 692002: 90th percentile AQI 632003: 90th percentile AQI 642004: 90th percentile AQI 632005: 90th percentile AQI 632006: 90th percentile AQI 592007: 90th percentile AQI 732008: 90th percentile AQI 732009: 90th percentile AQI 692010: 90th percentile AQI 692011: 90th percentile AQI 712012: 90th percentile AQI 642013: 90th percentile AQI 612014: 90th percentile AQI 582015: 90th percentile AQI 592016: 90th percentile AQI 562017: 90th percentile AQI 552018: 90th percentile AQI 542019: 90th percentile AQI 532020: 90th percentile AQI 522021: 90th percentile AQI 542022: 90th percentile AQI 532023: 90th percentile AQI 572024: 90th percentile AQI 542025: 90th percentile AQI 581980: Median AQI 461981: Median AQI 441982: Median AQI 421983: Median AQI 471984: Median AQI 521985: Median AQI 461986: Median AQI 311987: Median AQI 471988: Median AQI 481989: Median AQI 441990: Median AQI 421991: Median AQI 431992: Median AQI 331993: Median AQI 401994: Median AQI 421995: Median AQI 371996: Median AQI 371997: Median AQI 391998: Median AQI 331999: Median AQI 412000: Median AQI 412001: Median AQI 412002: Median AQI 392003: Median AQI 382004: Median AQI 372005: Median AQI 352006: Median AQI 352007: Median AQI 532008: Median AQI 532009: Median AQI 462010: Median AQI 442011: Median AQI 522012: Median AQI 462013: Median AQI 432014: Median AQI 362015: Median AQI 342016: Median AQI 302017: Median AQI 322018: Median AQI 282019: Median AQI 292020: Median AQI 272021: Median AQI 322022: Median AQI 292023: Median AQI 312024: Median AQI 312025: Median AQI 291980198519901995200020052010201520202025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2025

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.

PollutantDays as main pollutantShare of monitored days
Fine particles (PM2.5)364100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025364287770000295892PM2.5
2024366308580000315471PM2.5
20233652758613003157197PM2.5
2022361303580000295368PM2.5
20213602916810003254118PM2.5
2020361317440000275275PM2.5
2019360308520000295372PM2.5
2018365305600000285493PM2.5
2017347277700000325568PM2.5
2016355278770000305672PM2.5
20153622561060000345980PM2.5
2014359260990000365879PM2.5
20133562201360000436196PM2.5
20123341801540000466487PM2.5
201134315918220005271108PM2.5
20103652091560000446996PM2.5
200936520515910004669108PM2.5
200836615221220005373108PM2.5
200736416919140005373132PM2.5
20063482796810003559106NO2
20053392617620003563112NO2
20042942246820003763109NO2
20033222417740003864134NO2
20023592659211003963169NO2
200134423510720004169138NO2
20003582589730004166114NO2
19993652699510004162111NO2
19983653333110003350113NO2
19973653095420003954104NO2
1996366308580000375698NO2
19953653145010003753102NO2
19943652649650004263113NO2
19933653026030004058103NO2
19923663155010003354103NO2
199136523712440004373104NO2
199036525510640004268103NO2
19892761829130004472105NO2
1988337185139130004877108NO2
1987365207146120004777111NO2
19863652867450003161117CO
198536322213380004672110NO2
1984366171175200005291116NO2
1983365205135241004795159NO2
1982365241108160004283130NO2
1981365231116162004479154NO2
1980365210108161714046126266NO2

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.

Counties in New York with a similar median AQI in 2025

All monitored counties in New York

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem