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Particle Pollution and Your Patients' Health

Clinical Scenario 5 for Particle Pollution

You have treated John for asthma since early childhood. He is skin-test positive for house dust mite antigen. He is now a sixth grader and comes to your office with his mother. You are a bit surprised by the visit, because his scheduled annual check-up was still a couple of months away. When inquiring why, you are told that he ran out of bronchodilator refills earlier than usual. His mother reports that during school days John is using his inhaled bronchodilator more frequently than before. On further questioning, she recalls that he has had a couple of nocturnal asthma attacks, which she controlled by “rescue” inhaled medication. John has not had any upper respiratory tract infection (URI) symptoms.

His mother mentions that since last September John has been attending a new middle school. She reports that he likes it very much; however, it is a bit noisy in the classroom because they are widening an interstate close to the school and the students can hear movement of heavy trucks and machinery going on all day long. John's mother reports that this work has been going on for at least half a year. His medical history since you last saw him is otherwise unremarkable. His home environment has essentially remained unchanged, with no pets. He has a few high-pitched wheezes over the anterior chest on expiration.


The extensive construction close to the school must have substantially increased the ambient air pollution level in and around the school. Because indoor pollution levels are related to outdoor concentrations, the quality of classroom air has likely been compromised as well. The outdoor air pollution mix near construction sites contains, apart from gaseous pollutants, both crustal particle pollution (from moving and hauling away dirt) and mobile source–related particle pollution dominated by diesel engine-generated exhaust. The crustal particle pollution typically comprises large particles, such as silicates and iron oxide, that will sediment not far from the source. In contrast, diesel-powered trucks and construction equipment generate smaller particles—mostly fine (PM2.5) and ultrafine (PM0.1) particles. 

Studies among people with asthma show a strong association between ambient air particle pollution levels and the severity of respiratory symptoms (Romieu et al., 1996; Peters et al., 1997). Schoolchildren living in communities with heavy road traffic report a substantial increase in both chronic and nocturnal cough (Braun-Fahrlander et al., 1997). Asthma prevalence is higher in children living within 100 meters of a freeway (Edwards et al., 1994). Other studies report an increase in use of asthma medication associated with elevated ambient fine and ultrafine particle pollution levels. In addition to increased frequency and severity of symptoms, the studies report higher use of beta-adrenergic agonists (Peters et al., 1997; von Klot et al., 2002).

Balanced response

According to the thorough discussion with John and his mother, chronic exposure to particle pollution is the most likely cause of John’s asthma flare. Since removing John from school is not an option, you may revise his treatment plan and increase the frequency of office visits to monitor his well-being. The school administrator and school nurse should be approached about improving air quality in the classrooms by running the ventilation system continuously and frequently changing the air filters, as well as reducing outdoor activities in the schoolyard.