Respiratory effects of exposure to diesel traffic in persons with asthma.
BACKGROUND
Air pollution from road traffic is a serious health hazard, and people with preexisting respiratory disease may be at increased risk. We investigated the effects of short-term exposure to diesel traffic in people with asthma in an urban, roadside environment.


METHODS
We recruited 60 adults with either mild or moderate asthma to participate in a randomized, crossover study. Each participant walked for 2 hours along a London street (Oxford Street) and, on a separate occasion, through a nearby park (Hyde Park). We performed detailed real-time exposure, physiological, and immunologic measurements.


RESULTS
Participants had significantly higher exposures to fine particles (<2.5 microm in aerodynamic diameter), ultrafine particles, elemental carbon, and nitrogen dioxide on Oxford Street than in Hyde Park. Walking for 2 hours on Oxford Street induced asymptomatic but consistent reductions in the forced expiratory volume in 1 second (FEV1) (up to 6.1%) and forced vital capacity (FVC) (up to 5.4%) that were significantly larger than the reductions in FEV1 and FVC after exposure in Hyde Park (P=0.04 and P=0.01, respectively, for the overall effect of exposure, and P<0.005 at some time points). The effects were greater in subjects with moderate asthma than in those with mild asthma. These changes were accompanied by increases in biomarkers of neutrophilic inflammation (sputum myeloperoxidase, 4.24 ng per milliliter after exposure in Hyde Park vs. 24.5 ng per milliliter after exposure on Oxford Street; P=0.05) and airway acidification (maximum decrease in pH, 0.04% after exposure in Hyde Park and 1.9% after exposure on Oxford Street; P=0.003). The changes were associated most consistently with exposures to ultrafine particles and elemental carbon.


CONCLUSIONS
Our observations serve as a demonstration and explanation of the epidemiologic evidence that associates the degree of traffic exposure with lung function in asthma.
National Heart and Lung Institute, Imperial College, and Royal Brompton Hospital, London, United Kingdom.
James
J
McCreanor
Paul
P
Cullinan
Mark J
MJ
Nieuwenhuijsen
James
J
Stewart-Evans
Eleni
E
Malliarou
Lars
L
Jarup
Robert
R
Harrington
Magnus
M
Svartengren
In-Kyu
IK
Han
Pamela
P
Ohman-Strickland
Kian Fan
KF
Chung
Junfeng
J
Zhang
D000328:Adult; D000393:Air Pollutants / Q000009:adverse effects*; D000397:Air Pollution / Q000009:adverse effects / Q000032:analysis; D001249:Asthma / Q000209:etiology* / Q000503:physiopathology; D018592:Cross-Over Studies; D004781:Environmental Exposure / Q000009:adverse effects* / Q000032:analysis; D004784:Environmental Monitoring; D005260:Female; D005541:Forced Expiratory Volume; D005742:Gasoline / Q000009:adverse effects; D006801:Humans; D008297:Male; D008450:Maximal Midexpiratory Flow Rate; D008875:Middle Aged; D009585:Nitrogen Dioxide / Q000009:adverse effects* / Q000032:analysis; D052638:Particulate Matter / Q000009:adverse effects*; D001335:Vehicle Emissions / Q000032:analysis; D014797:Vital Capacity
D000393:Air Pollutants; D005742:Gasoline; D052638:Particulate Matter; D001335:Vehicle Emissions; D009585:Nitrogen Dioxide