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.
Occupational and Environmental Medicine, Unit of Lung Toxicology, KULeuven, Herestraat 49, 3000 Leuven, Belgium.
Lotte
L
Jacobs
Tim S
TS
Nawrot
Bas
B
de Geus
Romain
R
Meeusen
Bart
B
Degraeuwe
Alfred
A
Bernard
Muhammad
M
Sughis
Benoit
B
Nemery
Luc Int
LI
Panis
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