Is PM2.5 From Air Pollution The Same As From Smoking?

 Air Pollution  Add comments
Jan 172013
 

 

I’m facing a bit of a quandary here. Just last week I was bragging about how air pollution isn’t as much a risk factor to health than much less glamorous topics such as overweight and lack of exercise. Since then, of course, we’ve had the biggest public health emergency I’ve seen in my six years here, with air pollution skyrocketing to an astounding 755 AQI and higher in much of northern China. So does this change anything I said? Can such a dramatic short term toxin change my overall assumptions about long term risks?

To help answer these questions, I emailed C. Arden Pope III, PhD, the Mary Lou Fulton Professor of Economics at Brigham Young University and one of the world’s most cited researchers of air pollution. I’ve based much of my articles on his excellent research, especially his important article comparing health risks of air pollution and smoking. Here’s a bit of our revealing conversation below:

Me: Even with a PM2.5 of 880 ug/m3 recorded last weekend in Beijing, that still only comes out to ~14 mg of PM2.5 per 24 hours, barely the equivalent of one cigarette which has 12 mg on average. Despite the scary news reports about our pollution emergency, is it still accurate to say this is still not even the same risk as 2 cigarettes, and any casual smoker every day is exposing his heart and lungs to much more dangerous levels than even today’s air pollution?

Pope: Yes. Cigarette smoking is an incredibly effective way to expose an individual’s body to very high levels of harmful fine particulate matter and combustion-related nasty stuff. High levels of ambient air pollution are an effective way to expose whole populations to harmful fine particulate matter and associated combustion-related pollutants. These high levels of air pollution that we are seeing in Beijing may be similar, in terms of excess risk, to smoking a cigarette or two per day.

We are learning that just one or two cigarettes per day substantially increases the risk of cardiopulmonary disease. Furthermore, who would suggest that there would not be large adverse health implications of having an entire population, including children, elderly, asthmatics, those with COPD or coronary artery disease, start smoking a cigarette or two per day for a while? Unlike cigarette smoking, exposure to ambient air pollution is involuntary and ubiquitously effects entire populations.

Is it accurate to compare PM2.5 from a cigarette versus air pollution as having the exact same health effects? In general the actual compounds are generally similar enough to compare them, and their morbidity would be equal?

I don’t know for sure, but I think so. I have attached my most recent work (that you already familiar with) that integrates air pollution, second hand cigarette smoke, and active smoking into a single integrated response function for cardiovascular disease and for lung cancer. As you know I think that the best evidence suggests that you can compare them, but for cardiopulmonary disease the response function is not linear. (For a more complete and nuanced discussion, see the discussion section of the attached paper.) It is also interesting to note that in the Institute of Medicine (of the National Academies of Sciences) report that reviews the effects of second hand smoke on cardiovascular disease, they conclude that “Both smoking and air pollution have been associated with heart attacks” providing further evidence of biological plausibility and suggesting that there are similar effects of exposure to fine particulate matter from cigarette smoke and ambient air pollution.

If we only use relative risks of PM2.5, which you generally use in your research, are we ignoring the cumulative RR from other air pollution compounds? Or is PM2.5 an accurate surrogate for overall health effects especially since most morbidity/mortality is associated with PM2.5 and not ozone/NOx/SOx etc? So it’s fair to say that the vast majority of morbidity/mortality from air pollution is from PM2.5?

Again, we don’t know for sure. However, PM2.5 seems to be the best indicator/index, so far, with regards to impact on health.

So there you go. Does this change anything for you? This is actually a very important discussion in terms of public health; isn’t the overall impact of smoking in China in terms of morbidity, mortality, and Disability Adjusted Life Years (DALY) still much worse for smoking than for outdoor air pollution? I think there’s plenty of room for further debate on this. I’m certainly not done with my own research and hope to further discuss with other leaders in their field. Leave your thoughts below…

Beijing AQI Emergency Hazardous



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  • Miriam

    I would think an important question in all of this is whether there have been any actual studies done of long term, regular exposure to air pollution at the levels seen here. Wouldn’t that affect all these discussions? We can say that being overweight correlates (we don’t know if it’s a cause or just another symptom)) with all the diseases of civilzation. But do we actually have any study that shows us definitively what the results of, say, growing up in this much pollution does to a person? Are they not all based on much lower average pollution rates than we normally see here? And are they not all based on short-term studies that extrapolate the risks from longer exposure? Furthermore, are there any that are anything more than simply correlative?

  • Miriam

    Some research I’ve found specific to smoking vs car pollution:

    http://www.medicalnewstoday.com/releases/12481.php

    That one suggests that smoking is worse than car pollution. However, it’s probaby important to note that the test was done in an extremely clean city, with car exhaust regulations much more stringent than here, and without taking into account other forms of pollutions (like coal, factories, etc). There’s disagreement about whether Beijing’s most serious problems are from cars or from factories.

    This article says that Xinmin Weekly carried the results of an environmental group’s survey that gives the whole “one day is worth 21 cigarettes” claim. They also say it’s backed up by a Tsinghua professor. However they fail to link to the article, give the name of the group that did the research or the name of the professor. It seems to be from Xinmin Weekly, the 2013 Jan 28 issue, but I don’t have a copy of that magazine:

    http://ajw.asahi.com/article/behind_news/social_affairs/AJ201302030021

    There has been some work done in other cities relative to the air pollution and its equivalent in smoking. If they are correct (which is the question) it would mean that the “21 cigarrettes per day” claim for Beijing is, if anything, wildly understating the danger:

    http://www.guardian.co.uk/society/2004/aug/28/environment.medicineandhealth
    http://www.healthylivingindia.org/2009/04/one-day-breathing-in-bombay-equivalent.html
    http://preventdisease.com/news/articles/milan_pollution_bad.shtml
    http://www.cleanhouston.org/air/index.htm

    Many places state that cigarrette smoking is far more dangerous than air pollution. However, I’ve noticed that their rationale is almost always that “far more people die every year from cigarrette smoking than from air pollution.” So that doesn’t actually tell us which one is more dangerous, if you had them in equivalent amounts. It only tells us that more people smoke than are exposed to dangerous levels of air pollution.

  • Miriam

    Some research I’ve found specific to smoking vs car pollution:

    http://www.medicalnewstoday.com/releases/12481.php

    That one suggests that smoking is worse than car pollution. However, it’s probaby important to note that the test was done in an extremely clean city, with car exhaust regulations much more stringent than here, and without taking into account other forms of pollutions (like coal, factories, etc). There’s disagreement about whether Beijing’s most serious problems are from cars or from factories.

    This article says that Xinmin Weekly carried the results of an environmental group’s survey that gives the whole “one day is worth 21 cigarettes” claim. They also say it’s backed up by a Tsinghua professor. However they fail to link to the article, give the name of the group that did the research or the name of the professor. It seems to be from Xinmin Weekly, the 2013 Jan 28 issue, but I don’t have a copy of that magazine:

    http://ajw.asahi.com/article/behind_news/social_affairs/AJ201302030021

    There has been some work done in other cities relative to the air pollution and its equivalent in smoking. If they are correct (which is the question) it would mean that the “21 cigarrettes per day” claim for Beijing is, if anything, wildly understating the danger:

    http://www.guardian.co.uk/society/2004/aug/28/environment.medicineandhealth
    http://www.healthylivingindia.org/2009/04/one-day-breathing-in-bombay-equivalent.html
    http://preventdisease.com/news/articles/milan_pollution_bad.shtml
    http://www.cleanhouston.org/air/index.htm

    Many places state that cigarrette smoking is far more dangerous than air pollution. However, I’ve noticed that their rationale is almost always that “far more people die every year from cigarrette smoking than from air pollution.” So that doesn’t actually tell us which one is more dangerous, if you had them in equivalent amounts. It only tells us that more people smoke than are exposed to dangerous levels of air pollution.

    • http://www.myhealthbeijing.com Richard Saint Cyr MD DABFM

      Yes, I just heard about that very disturbing study showing equivalence with 21 cigs. All I can say is I would love to see their analysis. Even last week there was another report saying beijing’s air was similar to secondhand smoke exposire in some airport smoking lounges. That sounds much more plausible! As I said in my article here http://t.cn/ScxQaV, an AQI300 = 250µg/m” x 18m”/day (÷1,000) = 4.5mg/d ÷12 = 38% of one cigarette a day. Do the math yourself on my own site! 1 cig usually = 12mg PM2.5. So how on earth did they come up with their numbers? And my data is from Dr C Arden Pope’s peer-reviewed journal article, and he’s basically the #1 source worldwide for air pollution data. And again, you have Dr Pope’s words in this article above…
      Subject: [myhealthbeijing] Re: Is PM2.5 From Air Pollution The Same As From Smoking?

    • http://www.myhealthbeijing.com Richard Saint Cyr MD DABFM

      Yes, I just heard about that very disturbing study showing equivalence with 21 cigs. All I can say is I would love to see their analysis. Even last week there was another report saying beijing’s air was similar to secondhand smoke exposire in some airport smoking lounges. That sounds much more plausible! As I said in my article here http://t.cn/ScxQaV, an AQI300 = 250µg/m” x 18m”/day (÷1,000) = 4.5mg/d ÷12 = 38% of one cigarette a day. Do the math yourself on my own site! 1 cig usually = 12mg PM2.5. So how on earth did they come up with their numbers? And my data is from Dr C Arden Pope’s peer-reviewed journal article, and he’s basically the #1 source worldwide for air pollution data. And again, you have Dr Pope’s words in this article above…
      Subject: [myhealthbeijing] Re: Is PM2.5 From Air Pollution The Same As From Smoking?

      • Miriam

        I’ve been looking into this a lot lately. More for interest
        than anything else. (I’m not a smoker and never will be, and I’m
        convinced that Beijing’s air is bad enough that I use air filters in my home and wear a mask.)

        Some of the relevent things I’ve looked at:
        1.Gaseous pollutants in Beijing urban area during the heating period 2007–2008: variability, sources, meteorological, and chemical impacts. W. Lin, X. Xu, B. Ge, and X. Liu Key Laboratory for Atmospheric Chemistry, Centre for Atmosphere Watch & Services, Chinese Academy of MeteorologicalSciences, Beijing 100081, China

        That one’s a bit old and the pollution is obviously higher now, but it does give exact measurements of all pollutant levels. That’s something I’ve had a hard time finding. Lots of generalized statements, but no real measurements. And this is of concern, I think. Beijing has a unique stew of pollutants, including things like heavy metals and bacteria-laden sand in addition to acid oxides, black carbon and all the “oxide’s.” So there’s no disagreeing with the numbers you’ve posted, as far as PM 2.5 goes. But how do we factor in things like mercury levels and how harmful they can be?

        2. http://factsanddetails.com/china.php?itemid=392
        This is basically a compilation of info on Beijing pollution from New York Times, Washington Post, Los Angeles Times, Times of London, National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, Lonely Planet Guides, Compton’s Encyclopedia. Interesting, but all non-scientific sources. It’s main info, again, is a breakdown of all the different junk flying around in our air beyond just PM 10, PM 2.5 and ozone.

        3. Mind the Gap, Environ Health Perspect. 2010 December; 118(12): 1643–1645.

        This one I found to be the most interesting. I would be curious to know your opinion of it if you ever care to read it. I’ll just quote from their conclusion:

        “The shape of the exposure–response relationship implies much larger public health benefits of reductions at the lower end of the dose spectrum (e.g., from reductions in outdoor air pollution) than from reducing the rate of active smoking, which seems
        counterintuitive and deserving of further study because of its
        importance for control policies. In addition, given the potential risks and consequent global disease burden, epidemiologic studies are urgentlyneeded to quantify the cardiovascular risks of particulate matter exposures from indoor biomass burning in developing countries, which lie in the dose gap of current evidence.”

        They’re seeing two concerning implications: First, that there isn’t much difference to health between smoking and particulate matter air pollution, even though the latter typically has far lower concentration. Second, that the mortality/PM2.5 concentration is highly non-linear, which is troubling and implies, again, that even if concentration levels are far smaller in air pollution than in heavy smoking, that ultimately the risk is not much different. They did get contributions from Dr. Pope.

        Something seeming to confirm that possible implication is the report from Capital Medical University’s lung cancer center head, Zhi Yiuyi, who to the China Daily confirmed research from the Beijing Institute for Cancer Research: that from 2000 to 2009 smoking rates among the Chinese remained flat; yet the rate of lung cancer increased by 60%. More study is needed, but in his opinion pollution was the explanation. If he is correct, that would imply that the air pollution is similar to smoking in the danger it poses, even if the mathematically measurable PM2.5 levels are far smaller. That would make sense if the risk is non-linear.

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  • http://www.facebook.com/bandabacks April Horton Back

    Here is my question. I live in Tianjin with my three young children between the ages of 3 and 5, and I want to know how great the risk is to my children. My understanding is that they are at a higher risk because their lungs are still developing, so if we live here for a few years and then move away, can the damage be reversed? Is the risk for lasting effects very great? At what AQI should I decide not to take my children outside (they don’t have any respiratory problems)? At what AQI should I put a mask on them? (We don’t wear masks now and we don’t have filters in our home. We’ve been here for a year and a half. I am not sure if I should be concerned about the pollution or not.) Do you think there’s a magic number of years you could live here before any permanent damage was done?

  • http://www.facebook.com/bandabacks April Horton Back

    Here is my question. I live in Tianjin with my three young children between the ages of 3 and 5, and I want to know how great the risk is to my children. My understanding is that they are at a higher risk because their lungs are still developing, so if we live here for a few years and then move away, can the damage be reversed? Is the risk for lasting effects very great? At what AQI should I decide not to take my children outside (they don’t have any respiratory problems)? At what AQI should I put a mask on them? (We don’t wear masks now and we don’t have filters in our home. We’ve been here for a year and a half. I am not sure if I should be concerned about the pollution or not.) Do you think there’s a magic number of years you could live here before any permanent damage was done?

    • http://www.myhealthbeijing.com Richard Saint Cyr MD DABFM

      I personally feel it’s a must to use air purifiers in your childrens bedroom for anyone living here more than a year. My personal cutoff for not going outside would certainty be 250-300, maybe even lower. A good N95 mask would allow some more freedom outside, but only if it fits well.

      Regards,
      Richard

      —————————-
      Richard Saint Cyr MD

      MyHealthBeijing.com –a family doctor’s guide to wellness in Beijing

    • http://www.myhealthbeijing.com Richard Saint Cyr MD DABFM

      I personally feel it’s a must to use air purifiers in your childrens bedroom for anyone living here more than a year. My personal cutoff for not going outside would certainty be 250-300, maybe even lower. A good N95 mask would allow some more freedom outside, but only if it fits well.

      Regards,
      Richard

      —————————-
      Richard Saint Cyr MD

      MyHealthBeijing.com –a family doctor’s guide to wellness in Beijing

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