With a special law on reducing fine dust taking effect on Friday, a local study warned that exposure to airborne fine particles could have a “lag effect” on patients with a chronic respiratory disease that worsens symptoms for several days more.

Researchers emphasized that the nation needs not only policies to tackle fine dust but complementary measures to lower the chance of respiratory health deterioration of people.

The Ministry of Environment said the special law on fine dust reduction and control would take effect on Friday, giving legal grounds for the government to impose restrictions on heavy emitters of fine dust particles.

The National Health Insurance Service Ilsan Hospital said in a recent report that an increase in fine dust concentration worsened asthma and chronic obstructive pulmonary disease (COPD).

The researchers analyzed data of Seoul residents hospitalized or receiving outpatient treatment due to asthma, COPD, or lung cancer from 2006 to 2016. There were 3,191,900 asthma patients, 285,900 with COPD, and 28,900 with lung cancer.

Among asthma patients, hospital visits went up by 0.23 percent in all age groups when the fine dust concentration (particulate matter with a diameter of 10 micrometers) increased by 10㎍/㎥ from 25㎍/㎥.

In the case of ultra-fine dust (particulate matter with a diameter of 2.5 micrometers), their visits rose by 0.2 percent when the fine dust concentration (particulate matter with a diameter of 10 micrometers) went up by 10㎍/㎥ from 15㎍/㎥.

Fine dust exposed three days before the outpatient visit of an asthma patient worsened the respiratory health of the patient. Ultrafine dust exposed seven days before was most highly associated with the deterioration of the health.

Ultrafine dust had a more significant impact on asthma patients than fine dust when they were hospitalized via an emergency room. An increase of fine dust by 10㎍/㎥ raised the ER hospitalization by 0.77 percent in asthma patients, and that of ultrafine dust by 10㎍/㎥, the rate up 1.55 percent.

In COPD patients as well, a higher concentration of ultrafine dust pushed up outpatient visits. COPD patients’ outpatient visits climbed 1.36 percent per 10㎍/㎥ increase of fine dust, and 0.6 percent per 10㎍/㎥ rise of ultrafine dust.

“Higher concentration of fine dust was found to have worsened the severity of symptoms of asthma and COPD patients, as shown in their admissions through ER,” the report said. “This suggests that fine dust management may play an important role in preventing severe deterioration in patients with chronic airway disease.”

The researchers went on to say that the government needs additional measures to curb the possibility of health deterioration caused by exposure to fine dust. For example, the government can develop a special alarm system for people with respiratory illnesses and the elderly, they said.

To manage the vulnerable groups well, the government should install fine dust measuring stations, supply fine dust-filtering masks, and install air purifiers in kindergartens, schools, senior centers and nursing homes, the researchers added.