Short-term effects of ambient PM and PM air pollution on hospital admission for respiratory diseases: Case-crossover evidence from Shenzhen, China.

BACKGROUND

Ambient PM (particulate matter with aerodynamic diameter ≤1 μm) is an important contribution of PM mass. However, little is known worldwide regarding the PM-associated health effects due to a wide lack of ground-based PM measurements from air monitoring stations.

METHODS

We collected daily records of hospital admission for respiratory diseases and station-based measurements of air pollution and weather conditions in Shenzhen, China, 2015-2016. Time-stratified case-crossover design and conditional logistic regression models were adopted to estimate hospitalization risks associated with short-term exposures to PM and PM.

RESULTS

PM and PM showed significant adverse effects on respiratory disease hospitalizations, while no evident associations with PM were identified. Admission risks for total respiratory diseases were 1.09 (95% confidence interval: 1.04 to 1.14) and 1.06 (1.02 to 1.10), corresponding to per 10 μg/m rise in exposure to PM and PM at lag 0-2 days, respectively. Both PM and PM were strongly associated with increased admission for pneumonia and chronic obstructive pulmonary diseases, but exhibited no effects on asthma and upper respiratory tract infection. Largely comparable risk estimates were observed between male and female patients. Groups aged 0-14 years and 45-74 years were significantly affected by PM- and PM-associated risks. PM-hospitalization associations exhibited a clear seasonal pattern, with significantly larger risks in cold season than those in warm season among some subgroups.

CONCLUSIONS

Our study suggested that PM rather than PM contributed to PM-induced risks of hospitalization for respiratory diseases and effects of PM and PM mainly occurred in cold season.