Chronic effects of ambient air pollution on respiratory morbidities among Chinese children: a cross-sectional study in Hong Kong

Table 2 Respiratory symptoms and diseases of the subjects

	All (%)				Boys (%)						Girls (%)
	Boys (n = 1141)		Girls (n = 1062)		LPD (n = 485)		MPD (n = 393)		HPD (n = 263)		LPD (n = 428)		MPD (n = 278)		HPD (n = 278)
*Respiratory symptoms*	n	%	n	%	n	%	n	%	n	%	n	%	n	%	n	%
Wheezing with shortness of breath	1088	2.2	1019	2.4	463	2.2	372	1.6	253	3.2	416	1.9	335	2.1	268	3.4
Wheezing with medication	1088	3.2	1019	3.0	463	3.0	372	2.7	253	4.3	416	2.9	335	3.0	268	3.4
Any wheezing	1088	5.1	1019	4.6	463	5.0	372	4.8	253	5.9	416	3.6	335	4.8	268	6.0
Cough at night	1069	20.1	984	20.6	457	18.6	368	23.4	244	18.0	400	14.8^***	327	24.5^***	257	24.9^***
Chronic cough	1130	4.6	1039	5.0	482	5.6	387	4.1	261	3.4	423	4.0	345	5.2	271	6.3
Phlegm with colds	1053	32.2	983	32.3	456	33.3	358	29.9	239	33.5	402	30.6	322	31.4	259	36.3
Phlegm without colds	1092	6.0	999	5.7	467	5.6^**	374	4.0^**	251	10.0^**	412	3.2^***	324	5.2^***	263	10.3^***
Sneeze with itchy-watery eyes	1098	29.9^#	1019	26.2^#	473	34.5^*	378	25.4^*	247	27.9^*	412	29.9^#	341	25.2^#	266	21.8^#
*Respiratory diseases*
Current asthma	1137	3.2	1056	2.1	484	3.1	391	2.6	262	4.2	424	2.1	354	1.7	278	2.5
Life-time asthma	1137	7.7	1056	6.5	484	7.4	391	7.2	262	8.8	424	6.6	354	5.9	278	7.2
Current bronchitis	1137	11.8	1056	10.6	484	12.8	391	9.7	262	13.0	424	10.1	354	10.5	278	11.5
Life-time bronchitis	1137	20.5	1056	19.4	484	23.8^*	391	16.9^*	262	19.8^*	424	21.5	354	17.2	278	19.1
Current allergic rhinitis	1137	32.7^**	1056	26.5^**	484	36.8^**	391	26.6^**	262	34.4^**	424	33.3^***	354	18.4^***	278	26.6^***
Life-time allergic rhinitis	1137	37.6^**	1056	31.7^**	484	41.9^*	391	32.0^*	262	38.2^*	424	38.4^***	354	22.9^***	278	32.7^***

LPD: low-pollution district; MPD: moderate-pollution district; HPD: high-pollution district.
^#P < 0.10; ^*P < 0.05; ^**P < 0.01; ^***P < 0.001.

ISSN: 1471-2458