Data Limitations and Use By Berkeley Lab
Data from low-cost AQI sensors for sale in the general consumer industry are subject to the capabilities, maintenance, calibration, proper installation, installation location and other limitations of these systems. Data from low-cost sensors do not usually meet the high quality standards compared to EPA permanent sensors found on the EPA’s AirNow Fire and Smoke Map.
AQI data using low-cost sensors are used by Berkeley Lab for informational purposes such as for generally tracking changing smoke plume conditions. Berkeley Lab decisions related to complying with Cal/OSHA requirements for outdoor worker protection purposes and other operational decisions will primarily be based on the EPA’s AirNow Fire and Smoke website sensor data.
FAQs
Q: Which AQI color coded chart should I use for reference purposes?
A: US EPA as described on their airnow.gov website. Our local Bay Area Air Quality Management District (BAAQMD) also references the same AQI index chart.
Q: What are the outdoor EPA AQI levels that trigger Lab guidance and response actions?
A: The Lab lists guidance for each of the EPA’s AQI levels beginning with 51-100 (moderate or yellow color). Actual response actions begin at 101 when building ventilation systems are placed in a Wildfire Smoke Mode (reducing the intake of outside air). Lab Operations may only begin to send out air quality notifications when air quality is considered unhealthy for the general public or an AQI level of 151-200. Additional notifications are sent out based upon changing smoke level conditions.
Q: What are the 24 hour and annual National Ambient Air Quality Standards (NAAQS) for Particulate Matter 2.5 microns (PM2.5) and which AQI are they correlated to?
A: The 24 hour standard is 35 ug/m3 which correlates to an AQI of 100 (upper limit of moderate air quality). Prior to May, 2024, the annual standard was 12 ug/m3 which is now currently 9 ug/m3 which correlates to an AQI of 50 (upper limit of good air quality).
Q: Should I use the PurpleAir sensor data, EPA sensor data or other manufacturer’s sensor data?
A: You can use which ever sensor data you feel works best for you to develop your own personal action plan for limiting your wildfire smoke impact; however, the Lab bases it’s guidance and response actions on the EPA’s outdoor sensor data found on the EPA’s AirNow.gov website. PurpleAir low cost sensors are also used by the Lab qualitatively for tracking surrounding smoke conditions.
Q: Is the iPhone app, BreezoMeter, AQI information acceptable to use for determining AQI conditions?
A: There are many apps available for obtaining AQI levels that may help you plan your day for avoiding wildfire smoke; however, the Lab uses sensor data from the EPA’s AirNow.gov website as the basis of our guidance and response actions given the integrity of their sensors and data.
Q: Who should I call if I experience smoke exposure symptoms?
A: If you are onsite or at a leased facility and experiencing wildfire smoke symptoms, contact your supervisor and Health Services (510-486-6266). Additionally, follow-up with your primary health care physician.
Q: What are the health symptoms from smoke exposure?
A: There are many symptoms including, but not limited to: coughing, trouble breathing, wheezing, asthma attacks, stinging eyes, scratchy throat, irritated sinuses, headaches and chest pain. Some symptoms may be similar to COVID-19 symptoms so it’s important to contact your primary health care provider. Contact Health Services for additional consultation.
Q: What averaging time frame is the EPA’s PM2.5 AQI based on?
A: The EPA’s National Ambient Air Quality Standard (NAAQS) for PM2.5 is based on a 24 hour averaging period.
Q: Which conversion factor should I apply if using the PurpleAir website?
A: Normally, you should use the US EPA correction factor and realtime setting; however, there is currently a known issue with the current version of the PurpleAir map affecting the US EPA conversion. This known issue can cause online sensors to appear offline or display negative numbers when AQI is already low. This occurs because of the way the conversion formula works. Obviously, the map should not act in this way. As such, PurpleAir is implementing a fix for this issue in the next map version; however, they do not currently have a timeline for that update. The links to PurpleAir on the wildfiresmoke.lbl.gov website are automatically set to the parameters to use (i.e., they do not apply the US EPA conversion until PurpleAir fixes this issue).
Q: I noticed the AirNow Fire and Smoke Map website references low cost PurpleAir (PA) sensors. How is this PA sensor data adjusted compared to the same sensors on the PA site?
A: The PA sensor data goes through quality control screening, EPA’s correction equation is applied to reduce bias and the NowCast algorithm is also applied.
Q: Is the PurpleAir and AirNow data shown in real time?
A: PurpleAir data can be displayed in real time whereas EPA data is updated on an hourly basis.
Q: Are the PurpleAir sensors the same quality as the EPA sensors?
A: The PurpleAir sensors are low cost, temporary sensors installed by general citizens whereas EPA sensors are expensive, permanent sensors that are maintained, calibrated and installed by trained EPA staff.
Q: If the AQI for the unhealthy range is reached for several minutes, does this mean I’m overexposed to wildfire smoke (PM2.5 particle pollution)?
A: No. The National Ambient Air Quality Standard (NAAQS) for Particulate Matter of 2.5 microns or less is based upon a 24 hour average.
Q: At what point (AQI level) will Lab operations be curtailed or stopped?
A: There are many factors that will be taken into consideration by senior Lab leadership. Lab wide communications will be provided during smoke events as they occur.
