Air Quality Health Index in primary care: A feasibility study

Figures & data

Figure 1. Decision algorithm rendered by the software product.

The software queried the Environment Canada database for Air Quality Health Index (AQHI) values ≥ 4 and sent AQHI alerts via text messages to participants in the affected areas in Toronto.

Figure 2. Forecast vs. Observed Air Quality Health Index (AQHI) in North Toronto during Study.

Summer and winter 2019 had the highest number of forecast AQHI alerts in North Toronto. Downtown Toronto followed a similar pattern of alerts for moderate health risk AQHIs.

Figure 3. Days with a moderate health risk in downtown Toronto during winter 2019.

Air Quality Health Index (AQHI) values of 4 – 6 carrying a moderate health risk tended to occur in clusters, indicating that risk will be concentrated rather than random.

Table 1. Forecast vs. Observed Air Quality Health Index (AQHI) in downtown and North Toronto during Study.^a

		Observed
		Toronto Downtown		Toronto North
		Yes	No	Yes	No
Forecast	Yes	38	24	35	28
	No	18	137	12	143
		Estimated Value	95% CI	Estimated Value	95% CI
	Prevalence (%)	25.8	(20.2 − 32.3)	21.6	(16.4 − 27.7)
	Sensitivity ^b (%)	67.9	(54 − 79.7)	74.5	(59.7 − 86.1)
	Specificity (%)	85.1	(78.6 − 90.2)	83.6	(77.2 − 88.8)
	PPV (%)	61.3	(51.2 − 70.5)	55.6	(46.2 − 64.6)
	NPV (%)	88.4	(83.8 − 91.8)	92.3	(87.9 − 95.1)
	Positive LR	4.6	(3.0 − 6.9)	4.6	(3.1 − 6.6)
	Negative LR	0.4	(0.3 − 0.6)	0.3	(0.2 − 0.5)
	False Positive Rate^c (%)	32.1	(19.1–50.8)	25.5	(13.2 − 44.6)
	Accuracy (%)	80.7	(74.8 − 85.7)	81.7	(75.9 − 86.6)

^aClinicians, in providing advice on AQHI alerts, as well as patients, in applying them to their daily lives, need to tradeoff the benefits of forecast AQHI alerts with an accuracy rate of 81% and sensitivity rate of about 75% and the harms of disease exacerbation due to exposure to poor air quality.

b or Probability of Detection.

c or False Alarm Rate.