[Effect of air pollution on health service demand of the elderly and middle-age patients with hypertension, cardiovascular and cerebrovascular diseases: based on analysis of data from CHARLS].

To study the association of air pollution with health service demand of the elderly and middle-age patients with cardiovascular and cerebrovascular diseases, and to provide a scientific basis for development of environmental protection policy and health service policy of the Chinese government.This study included survey data on self-evaluated health, outpatient service demand and inpatient service demand of the patients with hypertension, heart disease and stroke in 62 cities of 17 provinces from China Health and Retirement Longitudinal Study (CHARLS) in 2011 and 2013, and combined it with the data on the annual concentrations of inhalable particulate matter (PM(10)), sulfur dioxide(SO(2)) and nitrogen dioxide (NO(2)) of those provinces and cities. Conditional Logistic regression was carried out to assess the possible effects of air pollutants on self-evaluated health and health service utilization.The results showed that turning points existed in the effects of concentrations of NO(2) and SO(2) on the health service demand of the patients with hypertension, heart disease and stroke. The inpatient service demand of the hypertension patients increased with NO(2) concentration when it was lower than 35.1 μg/m(3) and decreased with NO(2) concentration for higher value. Self-evaluated health of the patients with heart disease and stroke decreased with SO(2) concentration when it was lower than 63.8 μg/m(3) and increased with SO(2) concentration for higher value. In addition, no evidence was found for the association between PM(10) and health service demand.Air pollution may have effects on health service demand of the patients with hypertension,cardiovascular and cerebrovascular diseases, and different air pollutants at high or low concentration may have different health effects.