The Effect of Participatory Heat Education on Agricultural Worker Knowledge

Figures & data

Figure 1. Study flow.

^aParticipant declined to take assessment, test was lost, or participant did not have time to complete. ^bParticipant declined to take assessment, lost-to follow-up, test was lost, or participant did not have time to complete. ^cParticipants for which knowledge assessment was available at least one time point.

Table 1. Participant characteristics by intervention versus comparison group, n (%).

	All (n = 83)	Comparison (n = 43)	Intervention (n = 40)
Age
18–24	12 (14%)	6 (14%)	6 (15%)
25–44	31 (37%)	15 (35%)	16 (40%)
45–64	31 (37%)	17 (40%)	14 (35%)
Older than 64	9 (11%)	5 (12%)	4 (10%)
Sex
Male	54 (65%)	24 (56%)	30 (75%)
Female	29 (35%)	19 (44%)	10 (25%)
Spanish reading
Very well	48 (58%)	24 (56%)	24 (60%)
Fairly well	25 (30%)	13 (30%)	12 (30%)
Not very well	6 (7%)	4 (9%)	2 (5%)
Not at all	4 (5%)	2 (5%)	2 (5%)
English reading
Very well	7 (8%)	5 (12%)	2 (5%)
Fairly well	7 (8%)	5 (12%)	2 (5%)
Not very well	16 (19%)	7 (16%)	9 (23%)
Not at all	44 (53%)	21 (49%)	23 (58%)
Don’t know/refused/missing	9 (11%)	5 (12%)	4 (10%)
Education level
Primary school or less	42 (51%)	22 (51%)	20 (50%)
Some or all of middle school	10 (12%)	6 (14%)	4 (10%)
Some or all of high school	24 (29%)	11 (26%)	13 (33%)
More than high school	6 (7%)	4 (9%)	2 (5%)
Don’t know/refused/missing	1 (1%)	0 (0%)	1 (3%)
Years living in US
Less than 1 year	25 (30%)	12 (28%)	13 (33%)
3–10 years	7 (8%)	2 (5%)	5 (13%)
More than 10 years	49 (59%)	28 (65%)	21 (53%)
Don’t know/refused/missing	2 (2%)	1 (2%)	1 (3%)
Country of origin
United States	3 (4%)	1 (2%)	2 (5%)
Mexico	78 (94%)	41 (95%)	37 (93%)
Don’t know/refused/missing/other	2 (2%)	1 (2%)	1 (3%)
Years working in agriculture in the US
Less than 1 year	29 (35%)	16 (37%)	13 (33%)
1 to 5 years	10 (12%)	5 (12%)	5 (13%)
6 to 9 years	7 (8%)	2 (5%)	5 (13%)
10 or more years	37 (45%)	20 (47%)	17 (43%)
H-2A status
H-2A worker	28 (34%)	14 (33%)	14 (35%)
Not H-2A	55 (66%)	29 (67%)	26 (65%)
Company
Small	19 (23%)	10 (23%)	9 (23%)
Large – 1	28 (34%)	14 (33%)	14 (35%)
Large – 2	36 (43%)	19 (44%)	17 (43%)
Started working outdoors this year
Before May	64 (77%)	33 (77%)	35 (88%)
During May	4 (5%)	2 (5%)	2 (5%)
During the first half of June	9 (11%)	6 (14%)	3 (8%)
Don’t know/refused/missing	2 (2%)	2 (5%)	0 (0%)
Receive HRI training in past year
Yes	57 (69%)	26 (60%)	31 (78%)
No	24 (29%)	16 (37%)	8 (20%)
Don’t know/refused/missing	2 (2%)	1 (2%)	1 (3%)
Informed by healthcare provider about selected personal health conditions^a
Diabetes mellitus	7 (8%)	5 (12%)	2 (5%)
High blood pressure	18 (22%)	10 (23%)	8 (20%)
Heart disease	3 (4%)	2 (5%)	1 (3%)
Overweight or obese	6 (7%)	2 (5%)	4 (10%)

^aCategories not mutually exclusive

Figure 2. Knowledge test scores by time point and group.

Table 2. Knowledge test scores by time point and group (N = 83, 43 comparison, 40 intervention).

	n	mean (sd)	median	min	max
Test 1^a
Intervention	37	4.6 (1.5)	4	2	9
Comparison	35	4.7 (1.6)	5	2	8
Test 2^b
Intervention	40	5.6 (1.7)	5.5	3	9
Test 3^c
Intervention	34	6.3 (2.0)	6	2	10
Comparison	31	5.0 (1.4)	5	3	8

^a3 intervention and 8 comparison tests missing because participants declined, test was lost, or participant did not have time to complete

^bOnly intervention group completed Test 2 (immediately following heat education)

^c6 intervention and 12 comparison tests missing because participants declined, dropped from study, test was lost, or participant did not have time to complete

Figure 3. Knowledge test scores by company size and group.

Table 3. ANOVA results with the main effects and interactions.

Primary analysis: Company, English reading, and intervention assignment
	df	SS	MS	F	P-Value
Company	2	18.4	9.2	2.5	0.10
English reading	2	8.9	4.5	1.2	0.31
Intervention group	1	15.9	15.9	4.3	0.04*
Residuals	45	173.4	3.9
Secondary analysis: Company, English reading, and intervention assignment with interactions
Company	2	18.4	9.2	2.8	0.07
English reading	2	8.9	4.5	1.4	0.27
Intervention group	1	15.9	15.9	4.9	0.03*
Company*English reading	3	17.5	5.8	1.8	0.17
Company*Intervention group	2	18.1	9	2.8	0.08
English reading*Intervention group	2	3.2	1.6	0.5	0.62
Company*English reading*Intervention group	1	7.9	7.9	2.4	0.13
Residuals	37	121.0	3.3
Secondary analysis: Company and intervention assignment with interaction
Company	2	13.7	6.9	2.2	0.12
Intervention group	1	16.7	16.7	5.3	0.03*
Company*Intervention group	2	23.3	11.6	3.7	0.03*
Residuals	52	163.2	3.1

SS = Sum of Squares; MS = Mean Square; *P values < 0.05

Note: There are no workers in the small company with English reading level “not very well,” in the large-1 company with “very/fairly well” in the intervention group, or in the large-2 company with “very/fairly well” in the comparison group.

Table 4. Comparison of the difference between Test 3 and Test 1 knowledge scores in intervention and comparison groups, overall and stratified by company.

	Intervention			Comparison			All
Company size	n	mean (sd)	median	n	mean (sd)	median	n	mean (sd)	median
Large-1	13	0.85 (1.6)	1	12	0.75 (1.5)	0	25	0.80 (1.5)	1
Large-2	12	2.80 (2.2)	3	7	−0.14 (2.0)	0	19	1.70 (2.5)	2
Small	6	0.83 (1.3)	1	8	0.38 (1.9)	1	14	0.60 (1.6)	1
All	31	1.61 (2.0)	2	27	0.41 (1.7)	1	58	1.05 (2.0)	1