On days when the air quality index in Bakersfield, California, or Allegheny County, Pennsylvania, climbs into the orange or red zone, parents face a deceptively simple question: should the kids play outside? According to the American Lung Association’s latest State of the Air report, that question confronts families far more often than most people realize. The organization found that nearly half of all children in the United States live in counties that recorded unhealthy levels of ozone or fine particulate matter (PM2.5) on at least some days during the study period.
The report, which the ALA publishes annually using federal monitoring data, grades every county with sufficient data on three measures: ozone pollution, short-term spikes in particle pollution, and year-round particle pollution. Its findings, released in spring 2025 and still shaping policy discussions as of April 2026, put a sharp point on a problem that tighter regulations have not yet solved.
Where the data comes from
The air quality readings behind the ALA’s grades originate from the EPA’s Air Quality System (AQS), a national network of thousands of monitoring stations operated by federal, state, local, and Tribal agencies. Each station feeds concentration data for pollutants like ground-level ozone and PM2.5 into a central database that also stores quality assurance records. That layered verification process is what makes AQS the backbone of virtually every major air quality assessment in the country.
The ALA translates those raw readings into letter grades using the EPA’s Air Quality Index breakpoints. For 24-hour PM2.5 readings, a concentration between 9.1 and 35.4 micrograms per cubic meter falls into the “Moderate” category. Readings between 35.5 and 55.4 micrograms per cubic meter are classified as “Unhealthy for Sensitive Groups.” Children land squarely in that sensitive category. Their lungs are still developing, and they tend to spend more active time outdoors than adults, breathing harder and pulling more polluted air deeper into smaller airways.
On the regulatory side, the EPA finalized a rule in March 2024 that lowered the annual PM2.5 National Ambient Air Quality Standard to 9.0 micrograms per cubic meter, down from 12.0. It was the first downward revision in more than a decade, driven by updated research linking long-term fine particle exposure to cardiovascular disease, respiratory illness, and premature death. The ALA uses that tighter ceiling as its benchmark for grading year-round particle pollution.
Anyone can access the same underlying data through the EPA’s AirData portal, which converts raw readings into searchable tables, maps, and AQI breakdowns by county. Parents, school administrators, and local health departments do not have to wait for the ALA’s annual scorecard to check historical pollution levels in their own communities.
Which places fare worst
The ALA’s report consistently flags the same regions. California’s Central Valley, including Fresno and Bakersfield, has ranked among the most polluted areas in the country for ozone and year-round particle pollution for more than two decades. Los Angeles, despite significant improvements since the 1970s, still receives failing grades for ozone. In the East, parts of Pennsylvania, Ohio, and West Virginia struggle with particle pollution tied to industrial emissions and geography that traps stagnant air in river valleys.
Wildfire smoke has reshaped the map in recent years. Western states have always contended with fire seasons, but the scale and duration of smoke events have grown. The 2023 Canadian wildfire season sent plumes across the Great Lakes, the Northeast, and the Mid-Atlantic, pushing AQI readings in cities like New York and Detroit into hazardous territory for days at a stretch. Those episodes show up in the ALA’s short-term particle pollution grades and help explain why counties that historically met federal standards are now failing.
The burden is not evenly distributed. Research published by the EPA and academic institutions has repeatedly shown that communities of color and low-income neighborhoods are more likely to sit near highways, industrial facilities, and other pollution sources. Children in those communities face a compounded risk: higher baseline exposure on ordinary days and fewer resources to escape spikes when air quality deteriorates.
What the report cannot tell you
The ALA’s “nearly half” figure is striking, but it passes through an interpretive lens that is not fully transparent. The organization counts days that exceed specific AQI breakpoints for ozone and short-term PM2.5, then estimates the child population in affected counties. The exact formula for weighting those day counts and translating them into a single national percentage is internal to the ALA’s methodology. Treating the ALA’s conclusions as identical to EPA findings would be a mistake. The EPA collects and publishes the data. The ALA interprets it through a grading system designed to communicate risk and push for policy action.
Geographic coverage introduces another layer of uncertainty. AQS monitoring stations cluster in urban and suburban areas where population density justifies the cost of equipment and staffing. Rural counties and many Tribal lands have fewer monitors, which means pollution levels in those areas may be underreported or estimated rather than directly measured.
The 2024 PM2.5 standard also raises a timing question. While the EPA finalized the tighter rule, the compliance timeline stretches over several years. States must first identify areas that fail to meet the new limit, then develop and implement emission reduction plans. Whether the stricter standard will produce measurable improvements for children in the near term depends on how quickly those plans move from paper to practice, and on whether the rule survives ongoing legal and political challenges.
There is a subtler analytical gap, too. The annual PM2.5 standard captures average year-round exposure, but children’s health risks spike during short-term pollution events: summer ozone episodes, wildfire smoke intrusions, temperature inversions that trap exhaust in valleys. A county can meet the annual average and still subject children to clusters of dangerous days. Whether the regulatory focus on annual averages inadvertently draws attention away from the acute spikes that matter most for children’s outdoor activity is a question the available evidence raises but does not resolve.
What families and schools can do now
For parents trying to act on this information, the most direct tool is AirNow.gov, the EPA’s real-time air quality reporting system. It provides daily and often hourly AQI readings by ZIP code. Checking local conditions before children spend extended time outdoors, particularly during summer months or when wildfire smoke is present, is the single most actionable step a family can take.
Schools and childcare centers can build AQI checks into daily routines, shifting recess indoors or rescheduling outdoor sports practices when readings reach the “Unhealthy for Sensitive Groups” threshold. Some districts in California and Colorado have already adopted formal air quality policies that trigger automatic schedule changes, a model that pediatric health advocates say should be standard nationwide.
Local governments and community organizations can use the publicly available monitoring data to spot patterns that a single annual grade might obscure. A county that rarely exceeds the annual PM2.5 standard could still experience clusters of high-smoke days during wildfire season. Mapping those episodes over several years can guide investments in clean-air shelters, HVAC filtration upgrades in school buildings, or targeted outreach to families of children with asthma.
Communities can also report suspected pollution violations through the EPA’s enforcement and compliance portal, though the degree to which citizen reports lead to timely enforcement actions varies widely by region and agency capacity.
Cleaner standards, persistent exposure
The ALA’s central finding rests on a solid foundation of federally collected data: the monitoring network is extensive, the AQI thresholds are grounded in health research, and the revised PM2.5 standard reflects the latest science on what fine particles do to developing lungs. What remains less certain is how quickly tighter rules will translate into cleaner air on the specific days and in the specific neighborhoods where children live, learn, and play.
The gap between regulation and reality is not new, but the scale of the problem the ALA describes suggests it is not closing fast enough. Wildfire smoke, which no single state can regulate away, is widening it. For the families caught in that gap, the practical path forward has two parts: use the federal monitoring tools that already exist to reduce day-to-day exposure, and stay engaged with the policy decisions that will determine whether the next generation of children breathes easier than this one.
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*This article was researched with the help of AI, with human editors creating the final content.
