This is a very simple question from someone who doesn’t work too intensely in air quality.
In the EPA correction factor equations, is relative humidity expressed as a whole number or as a decimal? i.e. 80 or .80? I couldn’t find anything in the documents that specifies which numerical form it is being used in. Is there an unspoken convention that I’m not aware of here?
The RH term in the EPA equations is the relative humidity in the range 1-100. You can see this from the coefficient used for the RH term, 0.0852; if RH was 0-1, the term would be insignificant, even at 50% RH.
The RH term reduces the PM2.5 value as RH increases to compensate for changes in size of particles due to water adhesion or fog entering the sensor.
Thanks, Doug. That’s what I was assuming because there would be such a negligible effect if expressed as a decimal value, but I don’t like making assumptions when it comes to calculating values!