The burden of lower respiratory infections is primarily evident in the developing countries. However, the association between size-specific particulate matter and acute lower respiratory infection (ALRI) outpatient visits in the developing countries has been less studied. We obtained data on ALRI outpatient visits (N = 105,639) from a tertiary hospital in Guangzhou, China between 2013 and 2019. Over-dispersed generalized additive Poisson models were employed to evaluate the excess risk (ER) associated with the size-specific particulate matter, such as inhalable particulate matter (PM10), coarse particulate matter (PMc), and fine particulate matter (PM2.5). Counterfactual analyses were used to examine the potential percent reduction of ALRI outpatient visits if the levels of air pollution recommended by the WHO were followed. There were 35,310 pneumonia, 68,218 bronchiolitis, and 2,111 asthma outpatient visits included. Each 10 μg/m3 increase of 3-day moving averages of particulate matter was associated with a significant ER (95% CI) of outpatient visits of pneumonia (PM2.5: 3.71% [2.91, 4.52%]; PMc: 9.19% [6.94, 11.49%]; PM10: 4.36% [3.21, 5.52%]), bronchiolitis (PM2.5: 3.21% [2.49, 3.93%]; PMc: 9.13% [7.09, 11.21%]; PM10: 3.12% [2.10, 4.15%]), and asthma (PM2.5: 3.45% [1.18, 5.78%]; PMc: 11.69% [4.45, 19.43%]; PM10: 3.33% [0.26, 6.49%]). The association between particulate matter and pneumonia outpatient visits was more evident in men patients and in the cold seasons. Counterfactual analyses showed that PM2.5 was associated with a larger potential decline of ALRI outpatient visits compared with PMc and PM10 (pneumonia: 11.07%, 95% CI: [7.99, 14.30%]; bronchiolitis: 6.30% [4.17, 8.53%]; asthma: 8.14% [2.65, 14.33%]) if the air pollutants were diminished to the level of the reference guidelines. In conclusion, short-term exposures to PM2.5, PMc, and PM10 are associated with ALRI outpatient visits, and PM2.5 is associated with the highest potential decline in outpatient visits if it could be reduced to the levels recommended by the WHO.

Background The burden of lower respiratory infection is primarily borne by developing countries. However, the association between particulate matter of different sizes and acute lower respiratory infection (ALRI) outpatient visits in developing countries is less studied. Methods We obtained data on ALRI outpatient visits (N = 105,639) from a tertiary hospital in Guangzhou, China between 2013 and 2019. Over-dispersed generalized additive Poisson models were employed to evaluate the excess risk (ER) associated with particulate matter [inhalable particulate matter (PM10), coarse particulate matter (PMc), and fine particulate matter (PM2.5)]. Counterfactual analyses were used to examine the potential percent reduction of ALRI outpatient visits if the levels of air pollution were as low as those recommended by the World Health Organization (WHO). Results There were 35,310 pneumonia, 68,218 bronchiolitis, and 2,111 asthma outpatient visits included. Each 10 µg/m3 increase of three-day moving averages of particulate matter was associated with significant ER [95% confidence interval (CI)] of outpatient visits of pneumonia [PM2.5: 3.71% (2.91%, 4.52%); PMc: 9.19% (6.94%, 11.49%); PM10: 4.36% (3.21%, 5.52%)], bronchiolitis [PM2.5: 3.21% (2.49%, 3.93%); PMc: 9.13% (7.09%, 11.21%); PM10: 3.12% (2.10%, 4.15%)], and asthma [PM2.5: 3.45% (1.18%, 5.78%); PMc: 11.69% (4.45%, 19.43%); PM10: 3.33% (0.26%, 6.49%)]. The association between particulate matter and pneumonia outpatient visits was stronger among male patients and in cold seasons. Counterfactual analyses suggested that PM2.5 was associated with the largest potential decline of ALRI outpatient visits [pneumonia: 3.89%, 95% CI: (3.24%, 5.52%); bronchiolitis: 4.35% (3.06%, 4.82%); asthma: 5.98% (1.92%, 10.37%)] if the air pollutants were reduced to the level of the reference guidelines. Conclusion Short-term exposure to PM2.5, PMc, and PM10 is associated with significant risk of ALRI outpatient visits, among which PM2.5 is associated with the highest potential decline in outpatient visits if it could be reduced to the WHO recommended level.

Background The burden of lower respiratory infection is primarily borne by developing countries. However, the association between particulate matter of different sizes and acute lower respiratory infection (ALRI) outpatient visits in developing countries is less studied. Methods We obtained data on ALRI outpatient visits (N = 105,639) from a tertiary hospital in Guangzhou, China between 2013 and 2019. Over-dispersed generalized additive Poisson models were employed to evaluate the excess risk (ER) associated with particulate matter [inhalable particulate matter (PM10), coarse particulate matter (PMc), and fine particulate matter (PM2.5)]. Counterfactual analyses were used to examine the potential percent reduction of ALRI outpatient visits if the levels of air pollution were as low as those recommended by the World Health Organization (WHO). Results There were 35,310 pneumonia, 68,218 bronchiolitis, and 2,111 asthma outpatient visits included. Each 10 µg/m3 increase of three-day moving averages of particulate matter was associated with significant ER [95% confidence interval (CI)] of outpatient visits of pneumonia [PM2.5: 3.71% (2.91%, 4.52%); PMc: 9.19% (6.94%, 11.49%); PM10: 4.36% (3.21%, 5.52%)], bronchiolitis [PM2.5: 3.21% (2.49%, 3.93%); PMc: 9.13% (7.09%, 11.21%); PM10: 3.12% (2.10%, 4.15%)], and asthma [PM2.5: 3.45% (1.18%, 5.78%); PMc: 11.69% (4.45%, 19.43%); PM10: 3.33% (0.26%, 6.49%)]. The association between particulate matter and pneumonia outpatient visits was stronger among male patients and in cold seasons. Counterfactual analyses suggested that PM2.5 was associated with the largest potential decline of ALRI outpatient visits [pneumonia: 3.89%, 95% CI: (3.24%, 5.52%); bronchiolitis: 4.35% (3.06%, 4.82%); asthma: 5.98% (1.92%, 10.37%)] if the air pollutants were reduced to the level of the reference guidelines. Conclusion Short-term exposure to PM2.5, PMc, and PM10 is associated with significant risk of ALRI outpatient visits, among which PM2.5 is associated with the highest potential decline in outpatient visits if it could be reduced to the WHO recommended level.