Are Exacerbations of Asthma and COPD Related to Daily Air Pollution Levels?

asthma, smog, air pollution
Are hospitalizations for asthma or COPD exacerbations in any way associated with daily air pollution levels for NO2, ozone, or particulate matter?

Nitrogen dioxide (NO2) is the air pollutant associated with the highest risk for hospital admissions from exacerbations of asthma and chronic obstructive pulmonary disease (COPD) in Berlin, Germany. This was among study findings recently published in the journal Respiratory Research.

The researchers sought to explore whether variations in daily air pollution levels of NO2, ozone, or particulate matter (PM) in Berlin, Germany, were related to hospitalizations for asthma or COPD. A retrospective time series analysis was therefore conducted among patients hospitalized for an acute exacerbation of asthma or COPD. The researchers calculated both single and multipollutant models, examined possible lags in effect, and assessed the effect of meteorological variables on the results. Data obtained between January 2005 and December 2015 were used to quantify the concentration-response.

Among patients with asthma who were hospitalized on the same day as NO2 exposure, the RR was 1.101 per 10 µg/m3 NO2 increase (95% CI, 1.013-1.195). In patients with COPD who were hospitalized on the same day as their exposure to NO2, the values were as follows: RR, 1.123; 95% CI, 1.081-1.168.

Exposure to ozone (95% CI, 0.904-1.020), PM10 (PM with an aerodynamic diameter of ≤10 µm; 95% CI, 0.990-1.127), or PM2.5 (PM with an aerodynamic diameter of ≤2.5 µm; 95% CI, 0.981-1.148) was not associated with increased RRs for hospitalization among patients with asthma. Additionally, RRs for hospitalization among patients with COPD were not increased from exposure to ozone (95% CI, 0.981-1.033), PM10

(95% CI, 0.988-1.032), or PM2.5 (95% CI, 0.966-1.019).

All of the RRs and CIs reported are related to the day of exposure. No increased risks for hospitalization were reported with a delayed occurrence of exposure on subsequent days.

Limitations of the current analysis include the fact that the researchers did not measure indoor air pollution or personal exposure to pollutants. Only COPD and asthma exacerbations that were associated with a hospitalization were included in the study, which most likely led to an underestimation of the effects of air pollutants on respiratory outcomes.

The investigators concluded that the findings from the analysis reported are based on urban background measurements of NO2, which are known to be consistently lower than the European limit values for ambient concentrations.


Hoffmann C, Maglakelidze M, von Schneidemesser E, Witt C, Hoffmann P, Butler T.  Asthma and COPD exacerbation in relation to outdoor air pollution in the metropolitan area of Berlin, Germany. Resp Res. 2022;23(1):64. doi:10.1186/s12931-022-01983-1

This article originally appeared on Pulmonology Advisor