Fine particles (PM2.5) are 2.5 micrometers in diameter or smaller, and can only be seen with an electron microscope. Fine particles are produced from all types of combustion, including motor vehicles, power plants, residential wood burning, forest fires, agricultural burning, and some industrial processes.

There are multiple formulas put forward by Environmental Protection Agencies (EPA). ISB bases their displayed AQI reading on the US EPA formula for informational purposes. We base our response procedures solely on PM2.5.

AirGradient (https://www.airgradient.com/schools/) provides real time air quality monitoring for schools. The platform provides insights into air quality developments that form the base for targeted improvements to the ISB facilities and procedures. AirGradient also develops their own air quality sensors for indoor and outdoor use.

ISB has four high quality air pollution sensors spread around campus. They measure Temperature, Humidity, CO2 and PM2.5. This data is sent real time to AirAgradient, where it is then linked to our public displays on campus and our website.

Proper outdoor PM2.5 monitoring needs to take into account several parameters to provide reliable data. One of these parameters is height of measurement. To avoid ground level dust and particles that impact the reliability of measurement, outdoor monitors are usually measuring between 2m and 7m from ground level. 

The duration of prolonged exposure is dependent upon individual research studies, but is often a period of several months to several years.  Prolonged exposure does not have a finite definition and is defined differently within individual studies. Typically these studies look at exposure over several years.  Beyond length of exposure, other factors, such as extent and consistency of exposure, elements of exposure, and the age/health of the participants play key roles in understanding the effects of prolonged exposure.  This article describes the complexity of controlling for variables when studying prolonged exposure.  

Based on ISB’s Air Quality guidelines, all outdoor activities will be cancelled when PM2.5 reaches 75. When the PM2.5 reaches 56, outdoor activities will be modified or moved indoors depending on their length and the level of physical exertion involved. These levels will be adjusted for those with medical conditions impacted by pollutants. Parents are encouraged to meet with the division administration and the school health coordinator to discuss additional modifications for their child should this be the case.

Real-time data is used so we can make a decisions about outdoor activities based on the pollution levels at the times students are scheduled to go outside. Pollution levels fluctuate dramatically within a short period of time and we want to ensure we can make reliable decisions in real-time.  Along with real-time data, we also watch the hourly average to be aware of trends. We also have a running 24 hour trend graph of the PM2.5 levels. All this information is available on our public web page.
Comparing data over the last six months has shown that Nichada Thani generally has a lower pollution level than downtown.  We have seen substantial peaks on monitors downtown during the morning and afternoon commutes, which has created dramatic increase to pollution levels, which we have not seen in Nichada.  When pollution levels are high, they appear to be lower in Nichada and decrease much faster.