It is with great interest to read a recent article of " Evidence of
the role of short-term exposure to ozone on ischaemic cerebral and cardiac
events: the Dijon Vascular Project (DIVA)" by Henrotin et al.1 They
detailed addressed the analysis procedure and considerations and presented
findings on the relationship of air pollution and ischaemic cerebral and
cardiac events in a large population-based setting. However, a few
methodological considerations need to be further discussed.
The human body is affected by the thermal environment, which is not
only air temperature and rain. A potential environment risk factor is, in
fact, influenced by many different climatic factors such as air
temperature, air humidity, vapor pressure, wind speed, cloud cover,
radiation flux, etc. Thus, meteorological conditions adjusted in the model
may not be appropriate from an epidemiological point of view since the
assumption was based on a significant association between climactic
variables and ischaemic cerebral and cardiac events. Yet, this was not
clearly addressed in the article in firstly evaluating if the association
existed.2 If there is no association, is it still appropriate to "adjust"
meteorological conditions for air pollution assessment? In addition, when
considering meteorological variables, wind speed, cloud cover, radiation
flux, etc also have certain influences on human beings besides air
temperature and humidity. Is it appropriate to ignore in the assessment?
Finally, sex difference examination is recommended since females may be
more sensitive to the environmental change than males.
Given that conflicting results exist worldwide, a suggestion is to
have a physically equivalent temperature (PET) by combining all the
relevant climatic variables to be adjusted when assessing the relationship
of air pollution and cardiovascular disease.3, 4 This may give a more
precise indication close to human experience in exposing to the weather.
No doubt, future studies are needed to firstly confirm the association of
PET and cardiovascular events and then with the effect of air pollution
before clinical practice can be made.
1. Henrotin J-B, Zeller M, Lorgis L, Cottin Y, Giroud M,
BÃÆ’ƒÃâ€Â ’ÃÆ’‚©jot Y. Evidence of the role of short-term exposure to
ozone on ischaemic cerebral and cardiac events: the Dijon Vascular Project
(DIVA). Heart 2010 0:hrt.2010.200337v1-hrt.2010.200337;
doi:10.1136/hrt.2010.200337
2. McArthur K, Dawson J, Walters M. What is it with the weather and
stroke? Expert Rev Neurotherapeutics 2010;10:243-249
3. Hoppe P. The physiological equivalent temperature - a universal index
for the biometeorological assessment of the thermal environment. Int J
Biometeorol. 1999;43:71-5.
4. Matzarakis A, Mayer H, Iziomon MG. Applications of a universal thermal
index: physiological equivalent temperature. Int J Biometeorol. 1999;43:76
-84.
Conflict of Interest:
None declared
It is with great interest to read a recent article of " Evidence of the role of short-term exposure to ozone on ischaemic cerebral and cardiac events: the Dijon Vascular Project (DIVA)" by Henrotin et al.1 They detailed addressed the analysis procedure and considerations and presented findings on the relationship of air pollution and ischaemic cerebral and cardiac events in a large population-based setting. However, a few methodological considerations need to be further discussed.
The human body is affected by the thermal environment, which is not only air temperature and rain. A potential environment risk factor is, in fact, influenced by many different climatic factors such as air temperature, air humidity, vapor pressure, wind speed, cloud cover, radiation flux, etc. Thus, meteorological conditions adjusted in the model may not be appropriate from an epidemiological point of view since the assumption was based on a significant association between climactic variables and ischaemic cerebral and cardiac events. Yet, this was not clearly addressed in the article in firstly evaluating if the association existed.2 If there is no association, is it still appropriate to "adjust" meteorological conditions for air pollution assessment? In addition, when considering meteorological variables, wind speed, cloud cover, radiation flux, etc also have certain influences on human beings besides air temperature and humidity. Is it appropriate to ignore in the assessment? Finally, sex difference examination is recommended since females may be more sensitive to the environmental change than males.
Given that conflicting results exist worldwide, a suggestion is to have a physically equivalent temperature (PET) by combining all the relevant climatic variables to be adjusted when assessing the relationship of air pollution and cardiovascular disease.3, 4 This may give a more precise indication close to human experience in exposing to the weather. No doubt, future studies are needed to firstly confirm the association of PET and cardiovascular events and then with the effect of air pollution before clinical practice can be made.
1. Henrotin J-B, Zeller M, Lorgis L, Cottin Y, Giroud M, BÃÆ’ƒÃâ€Â ’ÃÆ’‚©jot Y. Evidence of the role of short-term exposure to ozone on ischaemic cerebral and cardiac events: the Dijon Vascular Project (DIVA). Heart 2010 0:hrt.2010.200337v1-hrt.2010.200337; doi:10.1136/hrt.2010.200337 2. McArthur K, Dawson J, Walters M. What is it with the weather and stroke? Expert Rev Neurotherapeutics 2010;10:243-249 3. Hoppe P. The physiological equivalent temperature - a universal index for the biometeorological assessment of the thermal environment. Int J Biometeorol. 1999;43:71-5. 4. Matzarakis A, Mayer H, Iziomon MG. Applications of a universal thermal index: physiological equivalent temperature. Int J Biometeorol. 1999;43:76 -84.
Conflict of Interest:
None declared