EnviroNearby

Lares, Puerto Rico air quality history

Daily Air Quality Index summaries from EPA monitors in Lares, Puerto Rico, 1999–2004.

86%
Good days in 2004
26
Median daily AQI, 2004
0
Days above 100 in 2004
73
Days with an AQI in 2004 (of 366)

In 2004, EPA reported a daily Air Quality Index (AQI) for Lares, Puerto Rico on 73 days. 63 of those days (86%) were in the Good range, and the median daily AQI was 26. That median is lower than the typical monitored county in Puerto Rico (median 29.5 across 4 counties), and lower than the typical monitored U.S. county (42). The main pollutant was fine particles (PM2.5) on 73 days.

EPA did not report an AQI for every day of 2004 here (73 of 366 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 2004; EPA's files for 2005–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1999, 2000, 2001, 2002, 2003, 2004) 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 46 of 55 days1999: Moderate 9 of 55 days19992000: Good 84 of 92 days2000: Moderate 8 of 92 days20002001: Good 90 of 105 days2001: Moderate 15 of 105 days20012002: Good 79 of 89 days2002: Moderate 10 of 89 days20022003: Good 84 of 95 days2003: Moderate 11 of 95 days20032004: Good 63 of 73 days2004: Moderate 10 of 73 days2004
  • 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 562000: 90th percentile AQI 462001: 90th percentile AQI 522002: 90th percentile AQI 522003: 90th percentile AQI 512004: 90th percentile AQI 531999: Median AQI 322000: Median AQI 292001: Median AQI 282002: Median AQI 312003: Median AQI 282004: Median AQI 26199920002001200220032004
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2004

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)73100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20047363100000265369PM2.5
20039584110000285172PM2.5
20028979100000315265PM2.5
200110590150000285274PM2.5
2000928480000294676PM2.5
1999554690000325669PM2.5

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 1999–2004 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem