The problem
Daniel and I sometimes joke that every month here in India, reduces our live span by about a year. Well, we’re actually only half joking. The other day for example the EU refused a ship full of grapes from India because inspectors found far too much pesticides. The grapes returned to India for the local market. Air pollution is one of the other subjects of interest. While sitting in a rickshaw I often worry about the effect the clearly visible and smell-able exhaust fumes and fine dust will have on my lung. My face never was so dirty at the end of the day with blowing or picking your nose results in more dust than snot. I started wondering if a simple face mask like commonly used in certain cities might be a good idea.
So i decided to find out roughly what the health consequences of air pollution are and if the cloth facemasks can actually reduce health effects of air pollution or if their main benefit is psychological.
In today’s blog I share my results with you, a quick and rough literature review. I specifically aimed my search for the cloth facemasks. They are less stigmatising, widely available and most importantly I wanted to find out if they actually work, since they are commercially sold for exactly this reason and so many people actually use them.
Any comments and suggestions are more than welcome! I would like to learn more and reviewing literature myself just takes me too much time!
‘Air pollution’
Just quickly some rough information about air pollution thanks to Wikipedia. I don’t know anything about air pollution so in order to find answers to my questions it might be helpful to understand a little more about the causative agent. There are several types of pollutants, gasses, particulates and toxic metals appear to be the most important. Common sources include traffic, fires, industry and dust from ‘nature’. (1)
Roughly one can say that particles of 10 micrometre and smaller (PM10) are capable of entering deep into the lungs therefore can potentially cause harm. The most important source of particles < 10 ųm is burning of fossil fuels. Even smaller particles (< 100 nanometres) may pass through the alveolar wall into the bloodstream and affect other organs. However they tend to retain in the airstream and only on contact with the alveolar walls will they remain in the lungs. (2,3,4)
Water solubility is another feature, beside size, that determines the potential risk of an agent. For example the water soluble ammonia and sulphur dioxide are deposited in the lining of the upper respiratory tract because they can dissolve in the lining of the airways, causing for amongst others irritation and bronchoconstriction. Nitrogen dioxide on the other hand is less soluble and reaches the bronchioles and alveoli more easily where it can lead to acute chemical pneumonitis.
Health effects of air pollution
Over the years lots of data has been collected on the hazardous effects of air pollution. One of those statistics tells us that ca 3 – 10% of all lung cancers has been caused by environmental agents like biomass fuels, diesel exhaust, environmental tobacco smoke, welding fumes, wood, etc. Symptoms and diseases associated with air pollution are the same as those associated with smoking. Lung cancers, fibrosis, chronic bronchitis, COPD all fall in this category. (4)
The most important agents causing cardiorespiratory disease are: particulates, sulphur dioxide, nitrogen dioxide, ozone, lead and carbon monoxide. There are few agents that deserve special mention because they are toxins that can enter the body via the lungs and cause effect in other organ systems. These include: benzene (bone marrow), Cadmium (kidneys), metallic mercury (kidneys and central nervous system) and carbon disulphide (nervous system and cardiovascular). I would like to note that currently I don’t know the toxic concentrations of these molecules. (4)
Several studies have shown that long term (how long?) residence in areas with high (specifics?) air pollution leads to increased morbidity and mortality of cardiovascular and respiratory disease. (4) However a recently released review of the American Heart Association highlights the following matters, pay attention to the second point as it is important for my question:
· Air pollution is a risk factor for heart disease
· Exposure to fine particulate matter over a few hours or weeks can trigger cardiovascular deaths, heart attacks, strokes, heart failure and irregular heartbeats, especially in susceptible individuals. (according to their own press release the association between premature death and short term exposure was small yet consistent)
· Long-term exposure to elevated concentrations of fine particulate matter even further increases cardiovascular risk and reduces life expectancy probably by several months to a few years for those with higher exposures (there is a strong association between ischemic heart disease and exposure to air pollution)
I have to confess I didn’t read their whole statement as it is 49 pages and this post is taking me far too long already.
Pune
According to statistics presented by the worldbank, Pune had a concentration of particulate matter ≤ 10 micrometre (PM10) of 47 micrograms per cubic meter in 2005. For your record, the annual mean particulate air quality guideline of the WHO recommends 20 micrograms or less. (3) The population of Pune has dramatically grown over the last few years leading to increased pollution. In addition though, the government has taken actions to start combatting air pollution. I’m not sure what the net effect of the above is on particulate concentrations. I have to say that Pune is a lot ‘cleaner’ than I expected, if you for example compare it to Delhi with 150 micrograms per cubic meter. (3)
Unfortunately I have not been able to find more detailed reports on what specific pollutants the air in Pune carries. However, using common sense I expect the products of fossil fuel burning is a major part.
Just for the purpose of my question I like to note that I’m most worried about those moments the exhaust of a vehicle is going straight in my rickshaw or when I’m walking through a cloud of dust because of some construction. Anyway, it’s a good starting point and I’m a little less worried.
Efficiency of wearing cloth facemask
The American Heart association included some recommendations in their report for individuals to reduce the harm. This included some obvious jet noteworthy advice, reduce time in traffic, minimize time outside during periods of high pollution and minimize other cardiovascular risk factors. Because of limited available data they did not formulated recommendations concerning the use of face-masks, despite some evidence in a few studies. (5) The same advice is given to known lung patients considering air pollution.
A recently published study showed that cloth masks (and other fabrics) did marginally prevent the penetration of 20 – 1000 nm sixed particles (for reference 1ųm = 1000nm). (6) There are several other studies looking at the effect of specialised facemasks in viral transmission. However those results are not in the scope of my search.
Most of the online, commercially available, cloth face masks didn’t mention anything about particle size filter capability; so not very helpful. Even a pubmed search to efficacy face mask amongst others or their effect on preventing lung disease, did not get me any really valuable results.
This study (8) showed a 75% penetrance of cotton handkerchiefs for particles <2.5ųm, and a 18-44 % penetration for unspecified cyclists masks. (8)
The American Lung Association specifically warns lung patients in fire season not to use dust masks, wet or dry bandanas or surgical mask as they are not effective in reducing smoke. I’m not so much interested in this because of the smoke, but because of their statement that these masks do not filter fine particles. Now this doesn’t mention cloth-masks, but bandanas are very close to cloth masks if you ask me. They do not mention their source though. (7)
Other hints I found were that ill-fitting mask will understandably reduce efficacy.
Conclusion
Particulates, which are double the WHO recommendation in Pune, are one of the major components in air pollution associated health problems. Therefore I feel safe to say we were right to worry about air conditions in Pune, despite the lack of more detailed information and the lower pollution than expected.
I’m not sure if our stay in Pune (ca 10 months) qualifies as “long term exposure”, but as we have seen even short term exposure has cardiovascular health risks.
To give myself a proper recommendation I ideally need a few more numbers. First, what is the ‘relative risk’ and what is the ‘actual risk’ for me to develop respiratory or cardiovascular disease during my stay as a consequence or air pollution. I also would like to know how much particles will be filtered by a mask and the numbers of risk reduction due to a cloth facemask. I’ll leave other health risks associated with my stay here outside the consideration. Unfortunately I have not been able to find this information.
The American heart association decided there is not enough evidence to make a recommendation about the use of face-masks and air pollution associated cardiovascular disease. However, this doesn’t include potential pulmonary benefits.
But since this has taken me far too long already I’ll make my conclusion based on what I collected so far and maybe revise my ideas later. Very simply the exposure to the air possess a (slight) health risk and potentially a cloth mask might reduce the risk. I seriously do not have enough information and the only conclusion I can make now is that I respect anyone involved in making these kind of advices!
Conclusion:
1. not enough information.
2. I’ll consider getting a mask purely for psychological reasons 
.
3. this is more difficult than I thought
So if anyone can help me out here! That would be awesome!
Literature
- 1. http://en.wikipedia.org/wiki/Air_pollution
- 2. http://en.wikipedia.org/wiki/Particulate
- 3. http://siteresources.worldbank.org/ DATASTATISTICS/Resources/table3_13.pdf
- 4. Harrison’s Principles of Internal Medicine. Fauci, Braunwald eo. 17th edition, 2008, Mc Graw Hill, United States.
- 5. Brook, Rajagopalan, Pope, and all. Particulate Matter Air Pollution and Cardiovascular disease. An Update to the scientific statement from the American Heart Association. Circulation; journal of American Hearth Association. September 21th, 2010.
- 6. Rengasomy, Eimer, Shaffer. Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles. Ann Occup Hygiene, June 28 2010.
- 7. http://www.alaw.org/air_quality/ outdoor_air_quality/fire_season.html
- 8. Beneficial cardiovascular effects of reducing exposure to particulate air pollution with a simple facemask. Particle and Fibre Toxicology 2009, 6:8
I know wikipedia is susceptible for false information. However, the information of wikepedia I used resembled the other information I found and cited.