Indoor air quality test methods for PM2.5 and PM10

Dale or Ian or any other experts on this forum, can you help with this question? I don't know, Tyler—been asking around.

I submitted an answer to this a month or so ago but for some reason it wasn’t posted. Anyhow, the LEED 2009 Reference Guide (pg. 466) says “but others may be used [provided] valid justification is provided” when it discussed the Compendium methods (published in 1990, not updated since, and typically not used by IAQ professionals). PM2.5 and PM10 are for outdoor air – not indoor air. Current ISO and ACGIH categories for human exposures to particulates include “total”, “inhalable”, “thoracic”, and “respirable”. The two of these that most closely resemble PM10 and PM2.5 and are readily available from industrial hygiene laboratories are the total and respirable, respectively. Both of these will overestimate the PM10 and PM2.5 levels so if the levels for these meet the LEED criteria then you can be assured the actual PM10 and PM2.5 levels would be similar or lower. I have done this for PM10 measurement for the LEED air testing credit numerous times and have never had it rejected.

The most common method for total particulates is the National Institute of Occupational Safety and Health (NIOSH) method 0500 (see http://www.cdc.gov/niosh/docs/2003-154/pdfs/0500.pdf). The respirable method is NIOSH 0600 (see http://www.cdc.gov/niosh/docs/2003-154/pdfs/0600.pdf). They are easy to do, inexpensive and some labs provide the sampling equipment if you have them do the analysis. You can find a list of labs accredited by the American Industrial Hygiene Association at http://apps.aiha.org/qms_aiha/public/pages/reports/publicScopeView.aspx?.... Most any IH lab should be able to do the NIOSH 0500 or 0600 methods.

Remember that PM2.5 sampling is only required if you are using LEED Version 4 and the building is in an EPA PM2.5 non-attainment area. In other words, the outdoor air is too dirty to meet the PM2.5 standard so you, as builders of buildings, have to make the indoor air cleaner than the outdoor air while the EPA itself says “Indoor air levels of many pollutants may be 2-5 times, and occasionally, more than 100 times higher than outdoor levels”. You should have to worry about what particles the building contributes to indoor air and not what is outside, which you cannot control. The USGBC IEQ TAG strikes again and continues to exclude those who know what they are talking about regarding IAQ.

Is the LEED definition of PM-10 dust all particles less than 10 microns in diameter? I thought EPA used it as the 50% cutoff between particles less than and greater than 10 microns.

Has laser particle counters been accepted as an acceptable method for measuring PM-10 dust?

Frankly, PM10 and PM2.5 are not appropriate for indoor air quality where the issue is human exposure.  They are for outdoor air where the main issues are particlates that interact with other atmospheric contaminants to create pollution (human exposure is important as well).  Health related paticle sizes are inhalable, thorasic, and respirable (see ACGIH TLV booklet).

Most commonly, two NIOSH methods are used (NIOSH 0500 for total particulate and NIOSH 0600 for respirable).  NIOSH 0500 would most closely mimic PM10 though it would likley overestimate.  NIOSH 0600 would mimic PM2.5 though it would also likely overestimate.  These two methods are easy and inexpensive for analysis.  I have used NIOSH 0500 for PM10 evaluation for LEED compliance successfully in the past.

Laser or optical particle counters can be used when a conversion factor is applied to convert the particles counted in the various size ranges to mass.  This conversion that is typically programmed into the instrument is based on a standard called Arizona Road Dust.  To get a true conversion for the particles that are actually being counted (unless you are measuring on an Arizona road) you have to co-sample the particles with a NIOSH 0500 and/or 0600 sample and compare the results to the instrument readings.  The conversion to get the LEED required micrograms per cubic meter can then be input to the instrument to get the more realistic measure of the particles in the indoor air in mass per volume.       

Has LEED approved using total dust to represent or over estimate PM-10?

Though I am not sure now, in the past a good explanation of your results, especially by an IAQ expert and/or CIH, is acceptable.  If you pass the LEED requirement for PM10 using total dust I can't imagine why it would be rejected especially when a well-vetted and industry standard method such as NIOSH methods are used.

Whoever wrote the initial LEED IAQ apparently did not do IAQ sampling as evidenced by their referral to the EPA IP methods.  The IP methods are old, outdated, and not commonly used in the industry.  The EPA-TO and NIOSH methods are commonly used plus some direct reading instruments for gases such as carbon monoxide and carbon dioxide.