In depth
Vasculitis and environment
Silica dust turns up in every study on this page, and the numbers agree with one another. Then there's smoking, which on this page points the opposite way from everywhere else on the site, and that finding needs care. It gets that care in four separate places on this page.
What the research found.
One review pooled six case-control studies on silica and ANCA-associated vasculitis. Ever having been exposed gave an odds ratio of 2.56, from 1.51 to 4.36. It was 3.95 for microscopic polyangiitis, from 1.89 to 8.24, and 3.56 for granulomatosis with polyangiitis, from 1.85 to 6.82.
One case-control study compared 111 people with eosinophilic granulomatosis with polyangiitis against 333 matched controls. Silica gave an odds ratio of 2.79, from 1.55 to 5.01, and organic solvents gave 3.19, from 1.91 to 5.34. Farming gave 2.71, from 1.71 to 4.29, which appears in that range too.
Among those 111 patients, people exposed to both silica and farming had an odds ratio of 9.12, from 3.06 to 27.19. Its authors read that as the two exposures multiplying rather than simply adding. Smoking ran the other way in that study, at 0.49 from 0.29 to 0.70.
Maritati and colleagues, Arthritis and Rheumatology, 2021
One case-control study compared ANCA-positive patients against a set of matched controls. Dust exposure came out at an odds ratio of 2.6, from 1.3 to 5.3, and occupational silica exposure at 3.4, from 1.1 to 9.9. No other environmental factor differed between the groups, and neither did smoking.
One study covered 2400 people with ANCA-associated vasculitis across two registries. Living further from the equator was associated with higher relapse risk, at an odds ratio of 1.41 from 1.14 to 1.74. More ambient ultraviolet B went the other way, at 0.82 from 0.70 to 0.99, and 0.71 in winter.
Silica, in every study that looked for it
One review pooled six case-control studies on silica and ANCA-associated vasculitis. Ever having been exposed came out at an odds ratio of 2.56, with the true value ranging from 1.51 to 4.36. That review also split its result by subtype, which is where it gets more interesting.
Microscopic polyangiitis came out at 3.95, from 1.89 to 8.24. Granulomatosis with polyangiitis came out at 3.56, from 1.85 to 6.82, and those two are close enough to suggest the exposure acts on the family rather than on one member of it. That's the first thing worth noticing on this page.
Two later studies reached that finding independently, without pooling anybody at all. One compared ANCA-positive patients against matched controls and found occupational silica exposure at 3.4, from 1.1 to 9.9, alongside general dust exposure at 2.6, from 1.3 to 5.3. The third came from a different subtype again, comparing 111 people with eosinophilic granulomatosis with polyangiitis against 333 matched controls, where silica came out at 2.79, from 1.55 to 5.01.
That's four results, three research groups, and several subtypes of the disease between them. They agree on the direction and they sit close together on the size, which is rarer than it sounds. Nothing else on this page comes close to that level of agreement.
Farming and solvents
The study of 111 patients looked at a good deal more than silica. Organic solvents came out at an odds ratio of 3.19, from 1.91 to 5.34, and farming came out at 2.71, from 1.71 to 4.29. Both of those are in the range the silica figures occupy, which is worth noticing.
One clinical review lists those exposures from the other direction entirely. Silica dust, farming, and long-term nasal carriage of Staphylococcus aureus all appear there as risks the field recognizes. It gives no figures, so nothing is quoted from it here beyond the list.
That last one is worth noticing on its own, because it's the only infectious exposure on any environment page across this site. This page can't put a number on it, because the review doesn't give one. So it's named here and left as a name.
Two exposures that multiply
Something unusual happens when those two exposures combine in the same person. Silica alone gave an odds ratio of 2.79 in that study and farming alone gave 2.71. People with both exposures came out at 9.12, which sits a long way above either of the two alone.
Its authors read that as the two exposures multiplying rather than simply adding together. Adding them would predict something a good deal smaller than 9.12, which is the point those authors were making. That's a real claim about mechanism, and it comes from a single study.
Now read the interval, because it ranges from 3.06 to 27.19 and spans a ninefold range. That width means very few people in the study had both of those exposures. So the direction of that finding is a good deal more trustworthy than the size of the number attached to it.
The exposure that runs the other way
One finding here points opposite to every other environment page on this site. It needs stating, and it needs stating carefully, because those two requirements pull against each other. What follows tries to do both at once.
In that study of 111 patients and 333 controls, smoking was significantly less common among the patients than among the controls. The odds ratio was 0.49, with the true value ranging from 0.29 to 0.70. Current and former smokers were counted together in that figure.
That's one case-control study, in one rare subtype, and it has never been explained. A second study on this page compared ANCA-positive patients against matched controls and found no difference in smoking at all. So the two studies don't agree with each other either, which is worth knowing before you repeat the figure.
Here is the part that counts for more than the number itself. Nothing on this page is a reason to smoke, and the reasons not to smoke are in heart and lung disease rather than here. Read this as a puzzle in the literature, because that's what it is, and treating it as anything else would be a misuse of one study.
What silica dust does and doesn't do on its own
One study complicates the silica story rather than supporting it. It looked at 86 men exposed to silica dust for an average of 22.3 years, and compared them against 28 controls. That's a long exposure and a small control group, and both facts count.
ANCA antibodies were commoner in the exposed men, at 17.1 percent against 3.6 percent. The rate rose with the amount of lung damage, ranging from 7.1 percent in those with exposure but no pronounced silicosis to 30.3 percent with simple silicosis and 36.0 percent with complicated silicosis. That gradient is the most interesting thing in the study.
Not one of those men had typical ANCA-associated vasculitis, which is the finding that changes what the rest means. Its authors drew the obvious conclusion, that silica exposure without established silicosis wasn't associated with ANCA production. That's their wording rather than an inference of ours.
So there are two separate things here and they get run together constantly. Having the antibody isn't the same as having the disease, and the dust seems to act through the lung damage rather than by itself. Both of those complicate a story that reads simply everywhere else.
Where you live, and relapse
One study came at this from a different angle entirely, covering 2400 people with ANCA-associated vasculitis across two registries. Then it asked about sunlight, which no other study on this page touches. It also asked about relapse rather than about who develops the disease in the first place.
Living further from the equator was associated with a higher relapse risk, at an odds ratio of 1.41 from 1.14 to 1.74. More average ambient ultraviolet B went the other way, at 0.82 from 0.70 to 0.99. The effect was stronger when only winter measurements were used, at 0.71 from 0.57 to 0.89.
Its authors had expected the link to be limited to one form of the disease, and it wasn't limited at all. A finding the authors weren't looking for survives a paper better than most. That said, it's still one study drawn across two registries rather than a set of them.
Read what was measured before reading what it means, because this is ambient sunlight at somebody's address. No vitamin D level was measured at all. Individual sun exposure was never measured either, and this page gives no target for either one.
What these trials didn't test
Every study on this page measured an exposure people already had, rather than assigning one to anybody. Not one of them removed an exposure and watched what happened next. That's a limit on all of them together rather than a criticism of any single one of them.
So a link here is a reason to look further rather than proof of a cause. Nothing here says what happens to the disease if an exposure stops, because those studies haven't been run. That's a different sentence from saying an exposure doesn't count.
Cutting avoidable dust exposure is sensible for its own reasons, and it doesn't need any of these figures to hold up. Calling it a treatment for vasculitis goes past all of them at once. The difference between those two sentences is the whole of this section.
What the figures are genuinely good for is a conversation with the people treating you. Tell them what you did for work and whether you ever farmed, going back as far as your first job. Those exposures often ended decades before any symptom appeared, and a job you left in 1983 won't be asked about unless you raise it.
Common misconceptions.
Myth. Silica is one study's idea.
Reality. It's in every study here that looked for it, which is unusual in this area. One review pooled six case-control studies and found an odds ratio of 2.56, from 1.51 to 4.36, while one later study found 3.4, from 1.1 to 9.9, and another found 2.79, from 1.55 to 5.01. Those came from different countries, different decades, and different subtypes of the disease, and they agree.
Myth. Smoking raises the risk here too.
Reality. One study found the opposite and it's worth stating plainly. It covered 111 people with a rare form of this disease and 333 controls, and smoking was less common among the patients, at an odds ratio of 0.49 from 0.29 to 0.70. A second study found no difference either way, and why the first result came out as it did is unknown. It's one finding in one subtype, it isn't a reason to smoke, and everything else known about smoking still applies.
Myth. Silica dust on its own is enough to cause this.
Reality. One study suggests it isn't enough on its own. It looked at 86 men exposed to silica dust for an average of 22.3 years, and ANCA antibodies were commoner in them than in controls, at 17.1 percent against 3.6 percent. The rate rose with lung damage, ranging from 7.1 percent with exposure alone to 36.0 percent with complicated silicosis. Not one of those men had typical ANCA-associated vasculitis, and its authors concluded that exposure without established silicosis wasn't linked to ANCA production.
Myth. Exposures just add up.
Reality. One study found two of those exposures multiplying rather than adding. Silica alone gave an odds ratio of 2.79 and farming alone gave 2.71, while people with both had 9.12, from 3.06 to 27.19. Adding the two would predict something much smaller than that. Read the interval too, because it ranges from 3 to 27 and rests on very few people with both exposures.
Myth. Where I live can't affect a disease like this.
Reality. One study of 2400 people found that it was associated with relapse rather than with getting the disease. Living further from the equator came out at an odds ratio of 1.41, from 1.14 to 1.74, while more ambient ultraviolet B went the other way, at 0.82 from 0.70 to 0.99. In winter alone the figure was 0.71. That's ambient sunlight at an address, and nothing was measured on a person, so it says less about you than it looks.
Cautions specific to this condition.
- Tell your team what you did for work, going back to your first job. Silica appears in three separate studies here and the exposure often ended decades before any symptom.
- Mention farming as well as industrial work. It came out at an odds ratio of 2.71 on its own, and at 9.12 combined with silica.
- Don't read the smoking result as permission. It's one case-control study in one rare subtype. Another study found no difference. Nothing here changes what smoking does to your heart and lungs.
- Read an interval ranging from 3.06 to 27.19 as very few people rather than as a ninefold risk.
- Treat the sunlight finding as a question. It measured ambient light at an address, not vitamin D in anybody's blood, and this page gives no target for either.
- No study here assigned an exposure. Every one measured an exposure people already had, which is weaker evidence than a trial.
Discuss any change with the rheumatologist who manages your care. Nothing here replaces that conversation.
Questions patients ask.
Which exposure has the most behind it?
Silica dust at work, and by a clear distance from anything else here. One review pooled six case-control studies and found an odds ratio of 2.56, from 1.51 to 4.36, one later study found 3.4, from 1.1 to 9.9, and another found 2.79, from 1.55 to 5.01. Three separate research groups looking at different populations found one direction and a similar size.
Does it differ between the types of vasculitis?
Less than you might expect, which is part of what makes the silica finding convincing. That review reported 3.95 for microscopic polyangiitis, from 1.89 to 8.24, and 3.56 for granulomatosis with polyangiitis, from 1.85 to 6.82. A separate study in eosinophilic granulomatosis with polyangiitis found 2.79, from 1.55 to 5.01. So the link turns up across all the main subtypes at a similar size.
What about farming?
It came out linked in the one study that looked at it directly. Among 111 patients and 333 controls, farming came out at an odds ratio of 2.71, from 1.71 to 4.29, and organic solvents at 3.19, from 1.91 to 5.34. One clinical review lists farming alongside silica dust and long-term nasal Staphylococcus aureus carriage as recognized risks.
Is it true that smoking is less common in people with this?
In one study, yes, and it needs holding carefully. That study covered 111 people with one rare subtype and 333 controls, and smoking came out at an odds ratio of 0.49, from 0.29 to 0.70. A second study found no difference at all between patients and controls, why the first result came out that way is unknown, and it isn't a reason to smoke.
Does silica dust alone cause this?
One study suggests not on its own, and it's the one that complicates the picture. It followed 86 men exposed to silica dust for an average of 22.3 years, and ANCA antibodies were commoner than in controls, with the rate rising with lung damage from 7.1 percent to 36.0 percent. Not one of those men had typical ANCA-associated vasculitis, so the antibody and the disease aren't one thing.
Does where I live make a difference?
One study of 2400 people found it was associated with relapse rather than with getting the disease. Living further from the equator came out at an odds ratio of 1.41, from 1.14 to 1.74, while more ambient ultraviolet B ran the other way, at 0.82 from 0.70 to 0.99. That measured sunlight at an address, so it's a question rather than an answer about any one person.
Would cutting an exposure now help?
No study here tested that, because every one of them measured what people had already been exposed to. So not one of them can say what happens when an exposure stops. Reducing avoidable dust exposure is sensible for other reasons, and calling it a treatment goes well past what any of this shows.
References.
- Gómez-Puerta JA; Gedmintas L; Costenbader KH. The association between silica exposure and development of ANCA-associated vasculitis: systematic review and meta-analysis. Autoimmun Rev. 2013;12:1129-35. 10.1016/j.autrev.2013.06.016Systematic review and meta-analysis of silica exposure and ANCA-associated vasculitis
- Maritati F; Peyronel F; Fenaroli P et al. Occupational Exposures and Smoking in Eosinophilic Granulomatosis With Polyangiitis: A Case-Control Study. Arthritis Rheumatol. 2021;73:1694-1702. 10.1002/art.41722Case-control study of 111 patients with newly diagnosed eosinophilic granulomatosis with polyangiitis against 333 general population controls matched for age
- Beaudreuil S; Lasfargues G; Lauériere L et al. Occupational exposure in ANCA-positive patients: a case-control study. Kidney Int. 2005;67:1961-6. 10.1111/j.1523-1755.2005.00295.xCase-control study of all consecutive ANCA-positive patients recorded at one laboratory between 1990 and 2000
- Bartůnková J; Pelclová D; Fenclová Z et al. Exposure to silica and risk of ANCA-associated vasculitis. Am J Ind Med. 2006;49:569-76. 10.1002/ajim.20327Study of 86 men occupationally exposed to silica dust for at least 5 years in Central Bohemia and followed in an occupational medicine department
- Rihova Z; Maixnerova D; Jancova E et al. Silica and asbestos exposure in ANCA-associated vasculitis with pulmonary involvement. Ren Fail. 2005;27:605-8. 10.1080/08860220500200395Structured questionnaire study of 31 patients
- Scott J; Havyarimana E; Navarro-Gallinad A et al. The association between ambient UVB dose and ANCA-associated vasculitis relapse and onset. Arthritis Res Ther. 2022;24:147. 10.1186/s13075-022-02834-6Study of patients with ANCA-associated vasculitis recruited to two registries
- Chevet B; Cornec D; Casal Moura M et al. Diagnosing and treating ANCA-associated vasculitis: an updated review for clinical practice. Rheumatology (Oxford). 2023;62:1787-1803. 10.1093/rheumatology/keac623Review of the diagnosis and treatment of ANCA-associated vasculitis for clinical practice
This page gathers the published research on this subject into one place. The studies behind it were published between 1989 and 2026, and every figure links to the paper it came from. Those studies were peer reviewed. This summary of them was not. Dr. Sarah Luebker is reviewing these pages one at a time and has not reached this one yet, so it carries no medical review date and nothing here is her opinion or her advice to you. Each page gets updated as she reaches it. It is here in the meantime because the science is worth having in one organized place that is easy to find and easy to read. Talk to your own clinician before acting on any of it.
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