EnviroNearby

Monmouth County, New Jersey air quality history

Daily Air Quality Index summaries from EPA monitors in Monmouth, New Jersey, 1980–2025.

91%
Good days in 2025
36
Median daily AQI, 2025
6
Days above 100 in 2025
265
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Monmouth, New Jersey on 265 days. 242 of those days (91%) were in the Good range, and the median daily AQI was 36. That median is lower than the typical monitored county in New Jersey (median 40 across 15 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 265 days. Across the years with fuller monitoring, the share of Good days rose: an average of 63% in 1980–1982 versus 89% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (265 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.

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 146 of 358 days1980: Moderate 166 of 358 days1980: Unhealthy for Sensitive Groups 18 of 358 days1980: Unhealthy 16 of 358 days1980: Very Unhealthy 12 of 358 days19801981: Good 252 of 365 days1981: Moderate 111 of 365 days1981: Unhealthy for Sensitive Groups 2 of 365 days1982: Good 282 of 361 days1982: Moderate 77 of 361 days1982: Unhealthy for Sensitive Groups 2 of 361 days1983: Good 276 of 360 days1983: Moderate 84 of 360 days1984: Good 294 of 364 days1984: Moderate 68 of 364 days1984: Unhealthy for Sensitive Groups 2 of 364 days1985: Good 325 of 365 days1985: Moderate 40 of 365 days19851986: Good 338 of 364 days1986: Moderate 26 of 364 days1987: Good 321 of 334 days1987: Moderate 13 of 334 days1988: Good 355 of 365 days1988: Moderate 10 of 365 days1989: Good 273 of 364 days1989: Moderate 49 of 364 days1989: Unhealthy for Sensitive Groups 27 of 364 days1989: Unhealthy 9 of 364 days1989: Very Unhealthy 6 of 364 days1990: Good 263 of 364 days1990: Moderate 64 of 364 days1990: Unhealthy for Sensitive Groups 20 of 364 days1990: Unhealthy 14 of 364 days1990: Very Unhealthy 3 of 364 days19901991: Good 271 of 365 days1991: Moderate 52 of 365 days1991: Unhealthy for Sensitive Groups 22 of 365 days1991: Unhealthy 13 of 365 days1991: Very Unhealthy 7 of 365 days1992: Good 305 of 366 days1992: Moderate 40 of 366 days1992: Unhealthy for Sensitive Groups 15 of 366 days1992: Unhealthy 5 of 366 days1992: Very Unhealthy 1 of 366 days1993: Good 291 of 365 days1993: Moderate 39 of 365 days1993: Unhealthy for Sensitive Groups 24 of 365 days1993: Unhealthy 10 of 365 days1993: Very Unhealthy 1 of 365 days1994: Good 298 of 365 days1994: Moderate 47 of 365 days1994: Unhealthy for Sensitive Groups 17 of 365 days1994: Unhealthy 3 of 365 days1995: Good 311 of 365 days1995: Moderate 38 of 365 days1995: Unhealthy for Sensitive Groups 10 of 365 days1995: Unhealthy 1 of 365 days1995: Very Unhealthy 5 of 365 days19951996: Good 276 of 364 days1996: Moderate 58 of 364 days1996: Unhealthy for Sensitive Groups 18 of 364 days1996: Unhealthy 11 of 364 days1996: Very Unhealthy 1 of 364 days1997: Good 301 of 365 days1997: Moderate 32 of 365 days1997: Unhealthy for Sensitive Groups 22 of 365 days1997: Unhealthy 7 of 365 days1997: Very Unhealthy 3 of 365 days1998: Good 288 of 365 days1998: Moderate 36 of 365 days1998: Unhealthy for Sensitive Groups 24 of 365 days1998: Unhealthy 16 of 365 days1998: Very Unhealthy 1 of 365 days1999: Good 303 of 365 days1999: Moderate 37 of 365 days1999: Unhealthy for Sensitive Groups 14 of 365 days1999: Unhealthy 10 of 365 days1999: Very Unhealthy 1 of 365 days2000: Good 313 of 366 days2000: Moderate 38 of 366 days2000: Unhealthy for Sensitive Groups 10 of 366 days2000: Unhealthy 4 of 366 days2000: Very Unhealthy 1 of 366 days20002001: Good 296 of 365 days2001: Moderate 42 of 365 days2001: Unhealthy for Sensitive Groups 19 of 365 days2001: Unhealthy 6 of 365 days2001: Very Unhealthy 2 of 365 days2002: Good 288 of 365 days2002: Moderate 35 of 365 days2002: Unhealthy for Sensitive Groups 26 of 365 days2002: Unhealthy 14 of 365 days2002: Very Unhealthy 2 of 365 days2003: Good 292 of 365 days2003: Moderate 48 of 365 days2003: Unhealthy for Sensitive Groups 16 of 365 days2003: Unhealthy 6 of 365 days2003: Very Unhealthy 3 of 365 days2004: Good 315 of 366 days2004: Moderate 41 of 366 days2004: Unhealthy for Sensitive Groups 8 of 366 days2004: Unhealthy 2 of 366 days2005: Good 314 of 365 days2005: Moderate 29 of 365 days2005: Unhealthy for Sensitive Groups 15 of 365 days2005: Unhealthy 7 of 365 days20052006: Good 304 of 365 days2006: Moderate 48 of 365 days2006: Unhealthy for Sensitive Groups 8 of 365 days2006: Unhealthy 5 of 365 days2007: Good 310 of 364 days2007: Moderate 37 of 364 days2007: Unhealthy for Sensitive Groups 11 of 364 days2007: Unhealthy 6 of 364 days2008: Good 306 of 366 days2008: Moderate 49 of 366 days2008: Unhealthy for Sensitive Groups 8 of 366 days2008: Unhealthy 3 of 366 days2009: Good 337 of 365 days2009: Moderate 23 of 365 days2009: Unhealthy for Sensitive Groups 5 of 365 days2010: Good 306 of 365 days2010: Moderate 49 of 365 days2010: Unhealthy for Sensitive Groups 6 of 365 days2010: Unhealthy 4 of 365 days20102011: Good 268 of 309 days2011: Moderate 31 of 309 days2011: Unhealthy for Sensitive Groups 8 of 309 days2011: Unhealthy 2 of 309 days2012: Good 205 of 256 days2012: Moderate 36 of 256 days2012: Unhealthy for Sensitive Groups 13 of 256 days2012: Unhealthy 2 of 256 days2013: Good 203 of 249 days2013: Moderate 42 of 249 days2013: Unhealthy for Sensitive Groups 3 of 249 days2013: Unhealthy 1 of 249 days2014: Good 223 of 248 days2014: Moderate 24 of 248 days2014: Unhealthy for Sensitive Groups 1 of 248 days2015: Good 189 of 236 days2015: Moderate 41 of 236 days2015: Unhealthy for Sensitive Groups 5 of 236 days2015: Unhealthy 1 of 236 days20152016: Good 204 of 236 days2016: Moderate 29 of 236 days2016: Unhealthy for Sensitive Groups 3 of 236 days2017: Good 245 of 258 days2017: Moderate 12 of 258 days2017: Unhealthy for Sensitive Groups 1 of 258 days2018: Good 220 of 245 days2018: Moderate 25 of 245 days2019: Good 217 of 240 days2019: Moderate 23 of 240 days2020: Good 209 of 226 days2020: Moderate 17 of 226 days20202021: Good 227 of 255 days2021: Moderate 24 of 255 days2021: Unhealthy for Sensitive Groups 3 of 255 days2021: Unhealthy 1 of 255 days2022: Good 226 of 248 days2022: Moderate 20 of 248 days2022: Unhealthy for Sensitive Groups 1 of 248 days2022: Unhealthy 1 of 248 days2023: Good 210 of 247 days2023: Moderate 35 of 247 days2023: Unhealthy for Sensitive Groups 2 of 247 days2024: Good 240 of 264 days2024: Moderate 23 of 264 days2024: Unhealthy for Sensitive Groups 1 of 264 days2025: Good 242 of 265 days2025: Moderate 17 of 265 days2025: Unhealthy for Sensitive Groups 4 of 265 days2025: Unhealthy 2 of 265 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 1291981: 90th percentile AQI 651982: 90th percentile AQI 591983: 90th percentile AQI 591984: 90th percentile AQI 571985: 90th percentile AQI 521986: 90th percentile AQI 481987: 90th percentile AQI 421988: 90th percentile AQI 381989: 90th percentile AQI 1051990: 90th percentile AQI 1011991: 90th percentile AQI 1051992: 90th percentile AQI 741993: 90th percentile AQI 931994: 90th percentile AQI 741995: 90th percentile AQI 671996: 90th percentile AQI 931997: 90th percentile AQI 871998: 90th percentile AQI 1121999: 90th percentile AQI 842000: 90th percentile AQI 672001: 90th percentile AQI 872002: 90th percentile AQI 1082003: 90th percentile AQI 902004: 90th percentile AQI 672005: 90th percentile AQI 642006: 90th percentile AQI 642007: 90th percentile AQI 672008: 90th percentile AQI 672009: 90th percentile AQI 482010: 90th percentile AQI 742011: 90th percentile AQI 612012: 90th percentile AQI 742013: 90th percentile AQI 642014: 90th percentile AQI 512015: 90th percentile AQI 742016: 90th percentile AQI 582017: 90th percentile AQI 472018: 90th percentile AQI 512019: 90th percentile AQI 502020: 90th percentile AQI 482021: 90th percentile AQI 542022: 90th percentile AQI 492023: 90th percentile AQI 612024: 90th percentile AQI 502025: 90th percentile AQI 501980: Median AQI 551981: Median AQI 421982: Median AQI 391983: Median AQI 391984: Median AQI 351985: Median AQI 341986: Median AQI 321987: Median AQI 261988: Median AQI 251989: Median AQI 331990: Median AQI 381991: Median AQI 381992: Median AQI 341993: Median AQI 351994: Median AQI 341995: Median AQI 331996: Median AQI 371997: Median AQI 361998: Median AQI 341999: Median AQI 312000: Median AQI 282001: Median AQI 332002: Median AQI 322003: Median AQI 312004: Median AQI 282005: Median AQI 312006: Median AQI 312007: Median AQI 312008: Median AQI 352009: Median AQI 292010: Median AQI 342011: Median AQI 362012: Median AQI 372013: Median AQI 402014: Median AQI 392015: Median AQI 412016: Median AQI 372017: Median AQI 312018: Median AQI 332019: Median AQI 372020: Median AQI 372021: Median AQI 362022: Median AQI 382023: Median AQI 392024: Median AQI 372025: Median AQI 361980198519901995200020052010201520202025
  • 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
Ozone265100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20252652421742003650161Ozone
20242642402310003750119Ozone
20232472103520003961140Ozone
20222482262011003849161Ozone
20212552272431003654154Ozone
2020226209170000374893Ozone
20192402172300003750100Ozone
20182452202500003351100Ozone
20172582451210003147101Ozone
20162362042930003758136Ozone
20152361894151004174154Ozone
20142482232410003951122Ozone
20132492034231004064151Ozone
201225620536132003774161Ozone
20113092683182003661179Ozone
20103653064964003474174Ozone
20093653372350002948126Ozone
20083663064983003567159Ozone
200736431037116003167164Ozone
20063653044885003164192Ozone
200536531429157003164185Ozone
20043663154182002867185Ozone
200336529248166303190226Ozone
20023652883526142032108220Ozone
200136529642196203387209Ozone
200036631338104102867214Ozone
1999365303371410103184203Ozone
19983652883624161034112205Ozone
199736530132227303687219Ozone
1996364276581811103793201Ozone
199536531138101503367233Ozone
199436529847173003474185Ozone
1993365291392410103593221Ozone
199236630540155103474218Ozone
19913652715222137038105237Ozone
19903642636420143038101221Ozone
1989364273492796033105215CO
1988365355100000253870CO
1987334321130000264273CO
1986364338260000324876CO
1985365325400000345284CO
19843642946820003557115CO
1983360276840000395980CO
19823612827720003959113CO
198136525211120004265108CO
1980358146166181612055129246CO

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 Jersey with a similar median AQI in 2025

All monitored counties in New Jersey

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