Subclinical responses in healthy cyclists briefly exposed to traffic-related air pollution: an intervention study.
BACKGROUND
Numerous epidemiological studies have demonstrated adverse health effects of a sedentary life style, on the one hand, and of acute and chronic exposure to traffic-related air pollution, on the other. Because physical exercise augments the amount of inhaled pollutants, it is not clear whether cycling to work in a polluted urban environment should be encouraged or not. To address this conundrum we investigated if a bicycle journey along a busy commuting road would induce changes in biomarkers of pulmonary and systematic inflammation in a group of healthy subjects.


METHODS
38 volunteers (mean age: 43 ± 8.6 years, 26% women) cycled for about 20 minutes in real traffic near a major bypass road (road test; mean UFP exposure: 28,867 particles per cm3) in Antwerp and in a laboratory with filtered air (clean room; mean UFP exposure: 496 particles per cm3). The exercise intensity (heart rate) and duration of cycling were similar for each volunteer in both experiments. Exhaled nitric oxide (NO), plasma interleukin-6 (IL-6), platelet function, Clara cell protein in serum and blood cell counts were measured before and 30 minutes after exercise.


RESULTS
Percentage of blood neutrophils increased significantly more (p = 0.004) after exercise in the road test (3.9%; 95% CI: 1.5 to 6.2%; p = 0.003) than after exercise in the clean room (0.2%; 95% CI: -1.8 to 2.2%, p = 0.83). The pre/post-cycling changes in exhaled NO, plasma IL-6, platelet function, serum levels of Clara cell protein and number of total blood leukocytes did not differ significantly between the two scenarios.


CONCLUSIONS
Traffic-related exposure to particles during exercise caused a small increase in the distribution of inflammatory blood cells in healthy subjects. The health significance of this isolated change is unclear.
Jacobs
Lotte
L
Occupational and Environmental Medicine, Unit of Lung Toxicology, KULeuven, Herestraat 49, 3000 Leuven, Belgium.
Nawrot
Tim S
TS
de Geus
Bas
B
Meeusen
Romain
R
Degraeuwe
Bart
B
Bernard
Alfred
A
Sughis
Muhammad
M
Nemery
Benoit
B
Panis
Luc Int
LI
D000328:Adult; D000393:Air Pollutants / Q000032:analysis / Q000506:poisoning*; D001530:Belgium; D001642:Bicycling / Q000502:physiology* / Q000706:statistics & numerical data; D001772:Blood Cell Count; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology; D045853:Exhalation / Q000187:drug effects; D005260:Female; D006801:Humans; D007249:Inflammation / Q000139:chemically induced; D019570:Inhalation Exposure / Q000009:adverse effects* / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000187:drug effects; D009569:Nitric Oxide / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis / Q000506:poisoning; D001335:Vehicle Emissions
D000393:Air Pollutants; D052638:Particulate Matter; D001335:Vehicle Emissions; D009569:Nitric Oxide