Particles and Health
Cloistered away in the depths of my laboratory or moving carefully and quietly, collecting samples at the “scene of the crime” I have been analyzing environmental particles for nearly forty years. The wonder I experienced in the beginning as I learned about the significance that a particle could have is solving a mystery has never left me. This text is a distillation of what I have learned as it applies to indoor environments. It is necessarily brief and is intended to be practical. The intimate behavior of particles, the physics of particle interaction with surfaces and fluids, is presented only to demonstrate the importance of sample location, sample type, and sampling technique. Much of what is presented here may be contrary to accepted practice but that, I suppose, should be expected.
Why Tapelift Samples
Air Quality and Surface Sampling using Tape
Our concern is about human health and the sense of well being. We have assumed that testing the air is the best way to assess exposure. That is the same assumption that was made in London during the great Cholera outbreak in the mid-1800’s. A fellow by the name of Steven Johnson has written a book about that called THE GHOST MAP. It is an interesting study of the persistence of the official requirement for taking air samples and the actual cause of Cholera (the water) that was demonstrated by John Snow. Thousands of lives could have been saved had it not been for the insistence on air samples to monitor exposures. It was noticed that the source of water seemed to be related to the outbreaks of cholera years earlier but in the opinion of William Farr, the “official” statistician for London, it had to be an airborne disease. Today John Snow’s work is a classic that all industrial hygienists study as part of their training. Just as back then, the official approach is air sampling. There is a disregard for the human being as an environmental sampling device. We are not static air pumps. Not even a simple examination of the physics of airflow over the body would allow such a flawed model. That is acknowledged but we take air samples anyway.
Everyone agrees that in order to sample the air quality in an environment it is necessary to take samples over a long time or repeated short-term samples over a substantial period of time. The time interval should include all cyclic events in the workspace and, ideally, have a temporal resolution sufficient to identify events that may result in discomfort. That can be done for gases (including water vapor as RH) and temperature. It is much more difficult for particles. It is assumed that small particles are the only ones that are collected by the respiratory system so we can sample particles that behave almost like gases. That assumption is wrong but it is “almost right”. Can clients afford the proper air sampling protocol? No!! So what do we do? We take one air sample, or maybe 20 while we are there. Each one represents a brief interval of time that may have nothing to do with the exposure that caused the problem. If there is not a CO2, O3, RH, or temperature problem we assume things must be OK. VOC, formaldehyde, or mold spores may be a problem. Particles other than mold are not considered because the standard air sampling devices do not efficiently collect particles that are known to cause problems. As a result, the main cause of the “sick building syndrome” (SBS) or “Building Related Illness” (BRI) has gone unidentified “Officially”, just like the cause of Cholera in London. The fact that the symptoms of SBS or BRI coincide with the symptoms caused by glass fiber is not a mistake. The presence of glass fiber on surfaces correlates well with the occurrence of these complaints, as documented in numerous studies here and in Europe.
The larger question still remains. Do you want to test the air quality or do you want to determine if the environment will have a detrimental effect on individuals exposed to it? The air needs to be tested and needs to be within certain tolerances for optimal performance of the workers in that environment. If there are still health complaints it is probably not the air that is the problem. Surfaces must be tested.
Articles of interest
Black Dust
No single case history would do justice to all the complaints involving black particles. Black particles are a common complaint in both the workplace and in the home. Contrary to popular belief black particles do not constitute a unique, single particle type. Combustion particles are typically black but every fuel creates its own unique distribution of particle types as already presented in the case of plant fuels. The combustion need not be local. Soot and charred products can travel considerable distances and deposit over time creating a black particle traffic arteriales nearby. Electric motors generate fine black metal wear and graphite particles that can become a black particle problem. Electric heating elements in baseboard heaters generate both metallic oxides and charred particles in the environment. When an electric heating element first heats up it both chars the particles that collected on the element since its last heating cycle and the element expands thus dislodging the particles into the convective air flow. The odor noticeable when the heater first heats up is the result of this initial burst of charred particles and volatilized pyrolysis products. Many fungal species generate black or dark spores that look black on light surfaces. Computer printers or copy machines can generate large amount of free toner particles. Toner particles can be a significant health risk. This is just a partial list of black particle types common in home and office environments. Each particle type is associated with its own health implications. Charred materials indicate incomplete combustion; carbon monoxide testing may be required. Black spores may be a localized Cladosporium population, possibly a problem; or Stachybotrys, a more serious situation.
At any given location multiple sources of black particles are present. The sample collected must be the black particles that cause the concern and not just any deposit of black particles. Black particles on the bathroom wall, black particles above an electric heating register, black particles on the window sill, and black particles collecting on white plastic surfaces in the kitchen are often all different. If the concern is the black particulate matter in the kitchen then that is the sample that should be taken. Sampling the air in this situation will only confuse and complicate the issue. The question in this case relates to a very specific population of surface particles. That is the sample that needs to be analyzed.
If you have any questions or would like to have Black Dust testing done please contact us.
Wildfire Smoke Soot Damage
Smoke damage contains a particle signature of the source. House fires, forest fires, brush fires, fireplace smoke, industrial fires, cigarettes, trucks, kitchen fires, etc. all leave a characteristic signature.
Pyrolyzed Calcium Oxalate Phytoliths
Some of the particles that mark these sources are shown here.
This is a tape lift from a home impacted by a near approach of a large forest fire. The bright rectangular particles in this field of view are from the pyrolysis of calcium oxalate phytoliths.
Charred Wood from a House Fire
This is a piece of charred Douglas fir (upper) and a hardwood from the structural wood used in this home. This particle was collected on a tape-lift taken on the second floor of a home that had a fire in the basement. This was carried upstairs by the chimney effect through the stairwells.
Wildfire Charred Wood
This is from a home impacted by a near approach of a large forest fire. There are fragments of three different species of trees in this image.
We can identify the source and if the environment (i.e home, office, school) has been impacted by smoke from that particular source.