Data Sources and Attribution

AllergyNest is built on other organizations’ data. Here is what each source is, what we use it for, how often it updates, how we credit it and the rules we follow.

Google Pollen API

What it is

Our pollen values come from the Google Pollen API, part of Google Maps Platform. Google reports the Universal Pollen Index, a scale from 0 to 5:

Index	Category
0	None
1	Very low
2	Low
3	Moderate
4	High
5	Very high

The values come from Google’s model. They are modeled estimates, not measured pollen counts, and they can be wrong. How our pollen index works explains more.

In the United States, Google gives an index for three pollen types (tree, grass and weed) and for 11 plants: maple, elm, cottonwood, alder, birch, ash, pine, oak, juniper, grasses and ragweed. It covers the 48 contiguous states and DC, but not Alaska, Hawaii or Puerto Rico, so we have no pollen pages there.

How we get the values

Our servers request values for 131 metro areas, twice a day each: after local midnight and again each morning, local time. Each metro’s values are for one point, the location of its main city. These requests carry nothing about you, and your browser doesn’t contact Google when you view a page. Each metro’s page shows when its values were retrieved.

How we credit Google

Every block that shows Google’s values ends with a credit line:

• Values as Google returned them: “Source: Includes pollen data from Google”, followed by “Google Maps”.
• Figures we compute from them, such as weekly highs: “Source: Includes pollen data from Google”, followed by “Includes data from Google Maps”.

How long we keep them

Google’s terms limit how long we may keep its values. We stop short of each limit to leave a margin:

Values	Google allows	We delete them after
Today’s values (the first day in each response)	365 days	358 days from when we first retrieved them
Forecast days	24 hours	22 hours

Each stored value carries its own expiry, and an hourly job deletes expired values. Pages that show the values are cached for at most one hour and leave out values that expire within that hour.

So each metro’s year in pollen covers at most the last twelve months, with no older history. Weeks before we began recording are marked “Not recorded”.

Rules for these values

• We show Google’s values only on our web pages: never in emails, notifications, social images, PDFs, widgets or exports, and never in anything sent to a sponsor.
• We don’t use them to train, test or improve AI or machine-learning models.
• You may not reuse them either. Google’s terms require it, so our Terms of Use forbid scraping, bulk downloading, caching, storing, republishing or redistributing the values, using them outside AllergyNest, or using them to train or improve machine-learning or AI models.

Our use of the Pollen API is subject to the Google Maps Platform Terms of Service. AllergyNest includes Google Maps features and content. Your use of them is subject to the then-current Google Maps End User Additional Terms of Service and the Google Privacy Policy.

National Weather Service

Each metro page shows the National Weather Service forecast for the location of its main city: the current and next 12-hour periods, with the sky, temperature, wind and chance of precipitation as NWS gives them. Our servers find each metro’s forecast grid through the NWS API, check it again every week because NWS grids can move, and fetch the forecast every two hours. The requests identify AllergyNest and give our contact address, as NWS asks, and carry nothing about you. NWS forecasts are open data, free to use for any purpose, and each page credits the National Weather Service and shows when the forecast was updated.

When the National Weather Service has an air quality alert or a dense smoke advisory in force for a metro’s main city, the page shows it beside the air quality readings: the alert’s name, when it ends, the alert’s own one-line account of what is happening (for example, which agency issued it and whether it is for wildfire smoke or ozone), the NWS office that issued it and a link to the full alert on weather.gov. Our servers check each metro for active alerts every hour, keep only the alerts in force and drop each one when it ends.

On days with pollen at Low or above, the page may add one sentence on how the day’s weather moves pollen, from fixed rules: likely rain (a chance of 60% or more), dry and windy weather (wind of 15 mph or more with a chance of rain under 30%), or light wind (5 mph or less, also dry). Each sentence cites its source, the American Academy of Allergy, Asthma & Immunology or the Asthma and Allergy Foundation of America.

AirNow

Each metro page shows current air quality from AirNow, the U.S. Environmental Protection Agency’s program with federal, state, local and tribal air quality agencies. Our servers request the latest observations near each metro’s main city every hour, shortly after AirNow publishes them, and keep only the latest set. For each pollutant reported, such as ozone and fine particles, the page shows the Air Quality Index (AQI) and its category as reported, with the AQI’s official color.

Following AirNow’s guidelines, the page labels the readings as preliminary, because they are not fully verified and can change; credits the reporting agency first, then AirNow; shows values and categories unaltered; and doesn’t use them for trends or history. A reading more than three hours old isn’t shown. If no monitor reports near a metro, the page says so.

FDA food recalls

Our food allergen recalls come from two FDA sources.

Company announcements

Companies announce many recalls themselves, and FDA posts those announcements on its recalls page, usually within a day. We check FDA’s recalls feed every hour and read the summary of each new announcement once: the dates, the product type, the reason, the company, the brand and the product. We show the announcements for foods and dietary supplements whose reason names one of the nine major food allergens, and link each one to FDA’s page, which has the lot codes, where the product was sold and what to do with it. Our requests to fda.gov name AllergyNest and wait 30 seconds between pages, as fda.gov asks of automated readers.

Our recall alert emails use these announcements only: on a day FDA posts one naming an allergen you chose, we email you that evening, US Eastern time, with the summary and a link to FDA’s page. Not every recall has an announcement, and the announcements are the companies’ own words. FDA posts some in Spanish as well; we show the English one. The contents of FDA’s website are in the public domain; we credit them as “Company announcements posted by the U.S. Food and Drug Administration (fda.gov)”.

Enforcement reports

The recall pages and archives come from FDA’s Enforcement Report, which lists every recall FDA monitors once FDA has classified it. We read it once a day through openFDA, FDA’s public data service, which updates it weekly.

From the food recalls in FDA’s reports since January 2024, we keep those whose reason mentions an undeclared allergen and names one of the nine major food allergens: milk, egg, peanut, tree nuts, wheat, soy, fish, shellfish or sesame. The allergen tags are ours, matched from FDA’s reason with a word list. Each recall’s page shows that reason in FDA’s words, with the product descriptions, codes, distribution and dates as FDA reported them. When FDA corrects a record, our copy changes with it, and we keep past recalls as an archive.

What this data can’t do:

• Alert you. A recall appears in the Enforcement Report only after FDA classifies it, often weeks after the company’s announcement, and openFDA asks that its data not be used to issue alerts to the public. Our recall alert emails never use it.
• Say whether a recall is still open. FDA doesn’t update a recall’s status after classifying it, so we don’t show one.
• Cover meat, poultry and egg products. The USDA’s Food Safety and Inspection Service regulates those and handles their recalls, so they aren’t in FDA’s data.

openFDA data is in the public domain. Each page that shows it carries the credit openFDA asks for: “Data provided by the U.S. Food and Drug Administration (https://open.fda.gov)”. AllergyNest isn’t affiliated with or endorsed by FDA. openFDA also asks that its data not be relied on for decisions about medical care.

CMS Doctors and Clinicians file

Our counts of allergists by state and metro area, also shown on state and metro pages, come from the Doctors and Clinicians file of the Centers for Medicare & Medicaid Services (CMS). It is built from Medicare enrollment records and the last 12 months of Medicare claims, with a row for each clinician’s practice address. CMS updates addresses and other general information monthly.

We count a clinician as an allergist when allergy/immunology is the primary or a secondary specialty in their Medicare enrollment, and count them once in each state and metro area where they have a practice address. We place each address by its ZIP code, using Census Bureau files that match ZIP code areas to counties and counties to metro areas, and divide by the Census Bureau’s population estimates. We leave out clinicians whose NPI number the national provider registry (NPPES) lists as deactivated in its monthly report.

The counts name nobody. Clinicians who aren’t enrolled in Medicare aren’t counted, and a count says nothing about appointments or waiting times. The files are public US government data. Each page that shows a count credits CMS and the Census Bureau, and the report offers the counts as a download.

The same file is one of the two sources of our allergist directory. There we show each doctor’s name, credential, specialty, practice name, address and phone number, and whether Medicare’s file marks them as having telehealth visits. Each doctor’s profile page also shows their National Provider Identifier and, from this file, their medical school and graduation year. These are public professional details; we show nothing else about them.

National provider registry (NPPES)

Every US health care provider has a National Provider Identifier (NPI). The national registry behind it, NPPES, run by CMS, lists each provider’s specialty codes and practice addresses, and CMS publishes it as a free monthly file. Providers keep their own records up to date, so some are years old.

Our allergist directory lists physicians whose NPPES record has an allergy or immunology specialty code, as well as those in Medicare’s file. Each listing says whether current Medicare records confirm it or only the registry does, with the date the doctor last updated their registry record; records not updated for five years are shown apart, as possibly out of date. We leave out deactivated NPIs, organizations, and nurse practitioners, physician assistants and others who chose an allergy code. CMS notes that an NPI doesn’t show that a provider is licensed or credentialed. How we list doctors has the details, and every listing has a “Report a problem” link.

US Census Bureau

We use four kinds of Census Bureau files:

• Metro area definitions: the July 2023 delineation of metropolitan areas and their principal cities.
• Population estimates for metro areas, for 2025.
• Place locations from the Census Gazetteer, to locate each metro’s main city. Where a Census point fell offshore, as for San Francisco, we use City Hall instead.
• ZIP Code Tabulation Areas from the Census Gazetteer, to match a ZIP code to its nearest metro for Pollen near you. A few ZIP codes, such as PO box and business ZIP codes, have no area on this map, so we can’t place them.

With the CDC data below, the first three give our list of 131 metros: the 100 most populous metro areas, the largest metro area in each contiguous state that would otherwise have none, and other metro areas with a National Allergy Bureau pollen station.

We rebuild the list from these files only when we update it. They are public US government data, credited here to the US Census Bureau.

CDC

From the CDC’s open data site, data.cdc.gov, we use historical averages of pollen-season timing at National Allergy Bureau stations, so that places with a station are on our metro list. We download it again only when we rebuild the list. It is public US government data, credited here to the CDC.

CDC PLACES

Each metro page can show the share of adults with current asthma in its main city, from the CDC’s PLACES project (Local Data for Better Health, 2025 release, mostly 2023 survey data). PLACES estimates this from national survey data with a statistical model, so it is an estimate with a margin of error, which we show, not a count. The 2025 release has no such estimates for Kentucky or Pennsylvania, so metros there show none. We download it again only when we rebuild our metro list. It is public US government data, credited on each page to the CDC.

NOAA climate normals

Each metro page shows climate averages for 1991–2020 from the U.S. Climate Normals of NOAA’s National Centers for Environmental Information: yearly precipitation and snowfall, the average temperature over the year, in winter (December to February) and in summer (June to August), and the length of the typical freeze-free season. For some cities we use the station the National Weather Service treats as the official climate site. For the rest, we take the main National Weather Service and airport stations within 30 miles of the city and choose the one with the fullest set of averages, or the nearest if several are equal. The page names the station and its distance. We download the normals again only when we rebuild them. It is public US government data, credited on each page to NOAA.

ENERGY STAR® certified air purifiers

Our air purifier finder lists the room air cleaners on the U.S. Environmental Protection Agency’s list of ENERGY STAR® certified models that are sold in the US, from data.energystar.gov. For each model it shows the values on that list as EPA publishes them: the clean air delivery rates for pollen, dust and smoke that the maker reported for certification, the room size ENERGY STAR calculates from the smoke rate, the main filter type, the measured ozone and the yearly energy use. We rebuild the list from EPA’s file each month and review the changes before they go live. EPA’s data is in the public domain. AllergyNest isn’t affiliated with ENERGY STAR or EPA, neither endorses us, and we don’t use the ENERGY STAR logo.

ENERGY STAR certified dehumidifiers

Our dehumidifier finder lists the dehumidifiers on EPA’s list of ENERGY STAR certified models that are sold in the US, from data.energystar.gov. For each model it shows the values on that list as EPA publishes them: the type (portable or whole-home), the capacity in pints a day and the efficiency from the U.S. Department of Energy’s test, the yearly energy use, the refrigerant and its global warming potential where listed, and whether the model meets ENERGY STAR’s Most Efficient criteria. Where EPA’s model name only names the product, such as “Dehumidifiers”, we show the first model number instead. We rebuild the list from EPA’s file each month and review the changes before they go live. The same public-domain license and the same terms apply as for the air purifier list.

Allergen guide and write-up sources

Each metro’s local write-up lists its sources below the text, with the publisher and the date we read each one, and every fact links to its source. Most are local or regional: city and county governments, state agencies, the USDA Forest Service, university extension services and the National Weather Service. A few write-ups mention a pollen count that a city or county published for one day, with that day’s date.

Each allergen guide lists its sources in a numbered list at the end, with the publisher and the date we read each one, and every claim links to its source. The most cited publishers are ACAAI, the FDA, AAAAI, AAFA, the USDA Forest Service and the CDC, followed by FARE, the EPA, university extension services, MedlinePlus and peer-reviewed journals. The “See an allergist if” card on every guide is based on ACAAI guidance, and the “Call 911” card on food, sting and latex guides on MedlinePlus’s list of anaphylaxis signs.

What we don’t have

• Mold. Google’s data has no mold, so we show no mold level. Each metro page links to the National Allergy Bureau’s measured pollen and mold counts, and our allergen guides describe common molds.
• Most weeds. Ragweed is the only weed Google reports by name, so other weeds have no plant-level values.
• Pollen counts. We don’t show live grain counts, the number of pollen grains a counting station measures in the air. A local write-up may quote a count that a public body published for a past day, with its date and source.

When data is missing or late

We say so, and we never fill a gap with an invented or estimated number:

• “Today’s values aren’t in yet” in the first two hours after local midnight.
• “Today’s update is late” if they still haven’t arrived.
• “No index” or “Out of season” when Google lists a plant without a value.
• “Unavailable” if we can’t read the data at all.

Report a data problem

If a value looks wrong, a credit is missing or a source link is broken, email hello@allergynest.com with the subject “Correction” and the page address. We will check it and fix our own mistakes, as our corrections policy describes.