EnviroNearby

Guayanilla, Puerto Rico air quality history

Daily Air Quality Index summaries from EPA monitors in Guayanilla, Puerto Rico, 1999–2017.

77%
Good days in 2017
32
Median daily AQI, 2017
0
Days above 100 in 2017
47
Days with an AQI in 2017 (of 365)

In 2017, EPA reported a daily Air Quality Index (AQI) for Guayanilla, Puerto Rico on 47 days. 36 of those days (77%) were in the Good range, and the median daily AQI was 32. That median is higher than the typical monitored county in Puerto Rico (median 24 across 7 counties), and lower than the typical monitored U.S. county (41). The main pollutant was fine particles (PM2.5) on 47 days.

EPA did not report an AQI for every day of 2017 here (47 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 (2012, 2013, 2014, 2015, 2016, 2017…) 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.

Share of monitored days in each AQI category, by year0%25%50%75%100%1999: Good 55 of 78 days1999: Moderate 23 of 78 days19992000: Good 80 of 96 days2000: Moderate 16 of 96 days2001: Good 85 of 111 days2001: Moderate 26 of 111 days20012002: Good 83 of 109 days2002: Moderate 26 of 109 days2003: Good 89 of 110 days2003: Moderate 21 of 110 days20032004: Good 83 of 96 days2004: Moderate 13 of 96 days2005: Good 88 of 109 days2005: Moderate 21 of 109 days20052006: Good 94 of 113 days2006: Moderate 19 of 113 days2007: Good 87 of 109 days2007: Moderate 22 of 109 days20072008: Good 102 of 109 days2008: Moderate 7 of 109 days2009: Good 26 of 27 days2009: Moderate 1 of 27 days20092011: Good 13 of 14 days2011: Moderate 1 of 14 days2012: Good 66 of 77 days2012: Moderate 11 of 77 days20122013: Good 108 of 112 days2013: Moderate 4 of 112 days2014: Good 26 of 27 days2014: Moderate 1 of 27 days20142015: Good 94 of 111 days2015: Moderate 17 of 111 days2016: Good 95 of 111 days2016: Moderate 16 of 111 days20162017: Good 36 of 47 days2017: Moderate 11 of 47 days2017
  • 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 year0501001999: 90th percentile AQI 592000: 90th percentile AQI 532001: 90th percentile AQI 552002: 90th percentile AQI 542003: 90th percentile AQI 542004: 90th percentile AQI 532005: 90th percentile AQI 582006: 90th percentile AQI 552007: 90th percentile AQI 532008: 90th percentile AQI 482009: 90th percentile AQI 342011: 90th percentile AQI 382012: 90th percentile AQI 512013: 90th percentile AQI 442014: 90th percentile AQI 382015: 90th percentile AQI 552016: 90th percentile AQI 572017: 90th percentile AQI 611999: Median AQI 382000: Median AQI 322001: Median AQI 392002: Median AQI 362003: Median AQI 322004: Median AQI 272005: Median AQI 302006: Median AQI 292007: Median AQI 322008: Median AQI 262009: Median AQI 212011: Median AQI 192012: Median AQI 232013: Median AQI 252014: Median AQI 192015: Median AQI 262016: Median AQI 312017: Median AQI 321999200120032005200720092012201420162017
  • 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.

PollutantDays as main pollutantShare of monitored days
Fine particles (PM2.5)47100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20174736110000326180PM2.5
201611195160000315774PM2.5
201511194170000265563PM2.5
2014272610000193855PM2.5
201311210840000254455PM2.5
20127766110000235171PM2.5
2011141310000193856PM2.5
2009272610000213454PM2.5
200810910270000264889PM2.5
200710987220000325378PM2.5
200611394190000295570PM2.5
200510988210000305872PM2.5
20049683130000275364PM2.5
200311089210000325481PM2.5
200210983260000365469PM2.5
200111185260000395577PM2.5
20009680160000325385PM2.5
19997855230000385966PM2.5

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 Puerto Rico

Source: U.S. EPA AirData, “Annual AQI by County” files for 1999–2017 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem