In reply to JIMBO:
> Yes it does... see GCSE biology and ciliated cells.
Er... it depends on the size of the particle....
http://www.surprising-science.de/en/individual-projects/health-risk-in-the-...
" Dust particles that are smaller than 2.5 micrometers can accumulate in the alveoli in our lungs — and once they make it there, we can’t get them back out of our bodies."
However, generally speaking, chalk particles are larger than this, although accumulation can occur if exposure is prolonged.
http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?post=1433329
"Chalk dust (calcium carbonate) is considered to be a relatively inert when compared to very bioactive dusts such as asbestose and silica. It has been used in controlled experiments to assess the effect of inert dusts on the sinuses. This is appropriate since the particles are typically of larger size, very few of which make it past the naso/oropharynx. Chalk dust significantly impairs the ability of the nasal passages to clear secretions and results in increased congestion and discomfort. With regards to the effect of chalk on the lungs, there have been a few case reports (particularly in Japan) that have linked a few school teachers with interstitial lung disease to chalk exposure. They did this by measuring the amount of chalk in the teachers lungs on autopsy and comparing them to others with interstitial lung disease without chalk exposure. It's not surprising that there have been very few cases reported of chalk causing ILD (interstitial lung disease) due to its inertness. This makes it very similar to coal dust, where relatively large and constant exposures are needed to result in lung disease. This is very different from dusts like silica and asbestose where single large exposures have caused acute respiratory failure and death. Of course it's bad to make too many assumptions concerning the cimilarity of coal to chalk, however it's probably safe to say that ILD from chalk exposure would likely occur only after very prolonged and heavy exposure.
The issue with asthma is somewhat different. Upper/large airway exposure even to completely inert dusts has been shown to trigger asthma and COPD exacerbations. Every time SLC gets a big ugly inversion, I get multiple calls from many patients with exacerbations of their obstructive lung disease. This type of reaction can lead to chronic airway inflammation with potentially dire consequences if left unchecked, however the progression will not be asymptomatic.
With regards to wood dusts, the particles are relatively large and almost never get past the upper airways. Studies have shown an increase in the frequency of nasal/sinus adenocarcinomas, however the increased rate of laryngeal, tracheal and lung cancers is very small and orders of magnitude less than the risk due to smoking. It's odd how so many of the people I've diagnosed with lung cancer refuse to believe the effect of smoking cigarettes for 30 years is the cause rather than [insert conspiracy theory here]. "
http://www.wisegeek.org/is-chalk-dust-harmful.htm
"In another sense, this material can and does accumulate in the human respiratory system, which means it can create long-term health problems due to overexposure. In short, swallowing a piece of white chalkboard chalk won't kill a person, but breathing in the dust for a number of years can create or trigger respiratory problems."