Table 1

Strength of evidence for causal relations for acute exposure to ambient levels

Mortality		Morbidity
Strong evidence	Moderate evidence	Strong evidence	Moderate evidence
All non-traumatic deaths⁹	All respiratory disease¹⁶  >Chronic obstructive pulmonary disease plus asthma in people aged ⩾65¹⁶		Emergency hospital admissions for all circulatory¹⁷ and all respiratory diseases^17,¹⁸ and ischaemic heart disease¹⁷ at all ages
			Emergency hospital admissions in people aged ⩾65 for chronic obstructive pulmonary disease plus asthma^17,¹⁸ and for pneumonia¹⁷
			Asthma admissions in children and younger adults¹⁷
			Accident and emergency attendances for asthma in children and younger adults¹⁹