CHAPTER 5: THE RESPIRATORY HEALTH EFFECTS ASSOCIATED WITH
5.4 Results
type of information being collected, and how that information would be used. The guardians/informants retained a signed copy of the informed consent forms.
5.3.3.3 Voluntary participation
Participants were informed that participation in the study was voluntary, and that failure to participate in the study or a withdrawal of consent at any stage was not going to be penalised in any way. Participants were informed that they were not obliged to answer any questions they did not wish to.
5.3.3.4 Avoidance of harm
The study did not place any participant in a potentially harmful situation, whether physically, emotionally, socially, politically, economically, and/or psychologically. All issues were discussed with sensitivity. The times and localities of the interviews was taken into consideration in order to ensure confidentiality. Guardians and participants were given the researcher’s contact details and were instructed to call if they felt the need to debrief after the interview had taken place.
2011). Later an African informal shack settlement grew on Kennedy Road around the landfill (GAIA 2011) and hence the area is predominately for African and Indians. Characteristics of the study populations are presented in Tables 5.1. It is worth noting that there are no Whites living in Clare Estate. Norton et al. (2007) reported a similar trend in North Carolina, USA where they observed that solid waste facilities were disproportionately located in communities of colour and low incomes.
Table 5.1 Demographic characteristics showing ages, gender and ethnicity groups of study participants.
Variable name (n = 23) Frequency Percent Ages (years)
6 1 4
7 2 9
8 3 13
9 5 22
10 4 17
11 2 9
12 6 26
Gender
Male 14 61
Female 9 39
Ethnicity
African 13 57
Indian 9 39
Coloured 1 4
5.4.2 PM2.5 concentration levels
In this study, only the mean PM2.5 concentration levels for a 24-hour measurement were reported. PM2.5 concentration levels recorded ranged between 16 to 218 µg m-3 from different households with a mean concentration of 76.5 µg m-3 with a standard deviation of 60.7 µg m-3 and a standard error of 12.6 µg m-3. The mean concentration is above the 24-hour average and an annual average of 65 and 25 µg m-3 of the NAAQS, respectively. The results show that there was a large variation (range = 202 µg m-3) of PM2.5 measurements. The most recorded PM2.5
concentration is 157 µg m-3. PM2.5 concentration levels and descriptive statistics are presented in Figure 5.1 and Table 5.2, respectively.
Table 5.2 Descriptive statistics for PM2.5 concentration PM2.5 concentration (µg m-3)
Mean 76.5
Standard Error 12.7
Median 63.0
Mode 157.0
Standard Deviation 60.7
Sample Variance 3689.2
Range 202.0
Minimum 16.0
Maximum 218.0
Confidence Level (95%) 26.3
Figure 5.1 Graph showing PM2.5 concentrations (µg m-3) in households near the landfill site
5.4.3 Spirometry
Spirometry was conducted in children from the 23 households randomly selected for PM2.5
sampling. Spirometric lung function data are summarized in Table 5.3. From a subset of 23 children age between 6 and 12 years, all children were able to perform spirometry successfully.
From those, only two respiratory outcomes were observed (35% with “normal” lung function test whilst 65% had “restrictive” test results. None of the children had a “constrictive” result. A mean of FEV1% was 82% (median of 82%, standard deviation of 41), a mean FVC of 75%
(median of 75%, standard deviation of 17), and a mean FEV1/FVC of 115% (median of 115%, standard deviation of 8). Evaluation of lung function at the individual level showed that 65%
of the children have an impaired lung function (FVC < 80%) of the predicted value. Forty-eight percent of children had FEV1 less than 80% of predicted, although no values were less than 60% of predicted. The common lung function impairment was of restrictive type characterized by the decrease in FVC to less than 80%. Airflow obstruction characterized by the decrease in FEV1/FVC to less than 70% of the predicted value was not found. A combination of both types of lung function decrement was also not found in children. Of all children, only 35% had normal lung function.
Table 5.3 Spirometric lung function measurements
Variable Male Female Total
Body mass index; mean (SD)
Height (mm) 1380 (±110) 1410 (±110) 1380 (±110)
Weight (kg) 32 (±31) 39 (±13) 33 (±22)
Age (years) 9 (±2) 10 (±2) 10 (±2)
% Predicted spirometric lung volumes in millilitres; Mean (SD)
FVC 66 (±20) 76 (±15) 75 (±17)
FEV1 76 (±60) 88 (±17) 82 (±41)
FEV1/ FVC 117 (±10) 115 (±6) 115 (±8)
Frequency of lung function patterns (%)
Normal 2 (9) 6 (26) 8 (35)
Restrictive 7 (30) 8 (35) 15 (65)
Constrictive 0 0 0
5.4.4 Correlations between PM2.5 and lung function.
Associations between 24 hour average PM2.5 concentration measured at homes and lung function conducted in children are presented in Table 5.5. Associations showed little or no heterogeneity for FEV1/FVC and PM2.5 concentration. The indirect correlation coefficient of 0.18 (r %predicted FEV1/FVC. PM2.5 concentration = -0.18) or indirect coefficient of determination of 0.0324 was observed (r2%predicted FEV1/FVC. PM2.5 concentration = 0.0324). However, associations of PM2.5
concentration and FVC or FEV1 were more heterogeneous. A strong association was observed between the % predicted FVC and PM2.5 concentration with a negative correlation coefficient of -0.60 (r%predicted FVC. PM2.5 concentration = -0.60) of a coefficient of determination of 0.36 (r2%predicted FVC. PM2.5 concentration = 0.36). Also, a moderate association between PM2.5 and FEV1 was observed. The results presented an indirect coefficient correlation of -0.41 (r%predicted FVC. PM2.5 concentration = -0.41) or an indirect coefficient of determination of 0.1681 (r2%predicted FEV1. PM2.5 concentration = 0.1681).
Most associations were negative, suggesting decreases in lung function of children with increasing exposure to PM2.5. Overall, there were statistically significant negative associations between FEV1 and PM2.5 levels. Similarly, we estimated statistically significant negative associations for FVC and PM2.5 levels. Table 5.4 presents PM2.5 concentration from all 23 participating households and respiratory outcomes from 23 children who participated in the lung function testing (spirometry), and Table 5.5 shows a Spearman’s correlation between PM2.5 and respiratory outcomes, respectively.
Table 5.4 Results of PM2.5 concentration and children’s respiratory outcomes
ID Age Gender Ethnic group
% Predicted FVC
% Predicted FEV1
%Predicted
FEV1/FVC Respiratory results
PM2.5
level (µg m-3)
1 8 Female Indian 81 93 117 Normal 21
2 7 Female Indian 84 88 106 Normal 22
3 10 Female African 99 109 112 Normal 19
4 11 Female African 98 110 115 Normal 24
5 10 Female African 84 93 113 Normal 28
6 8 Male African 89 95 106 Normal 16
7 12 Male Indian 120 261 137 Normal 27
8 12 Female African 99 112 116 Normal 22
9 9 Female Indian 75 88 118 Restrictive 64
10 12 Female Coloured 76 85 113 Restrictive 29
11 12 Female African 56 66 118 Restrictive 73
12 9 Female African 65 64 100 Restrictive 48
13 9 Female Indian 60 71 119 Restrictive 171
14 10 Female Indian 64 64 101 Restrictive 218
15 11 Female African 64 74 117 Restrictive 157
16 8 Female African 67 72 110 Restrictive 43
17 10 Male African 52 61 118 Restrictive 90
18 12 Male African 59 64 108 Restrictive 126
19 7 Male Indian 65 75 115 Restrictive 157
20 6 Male Indian 65 77 119 Restrictive 63
21 9 Male Indian 79 82 103 Restrictive 157
22 9 Male African 77 92 119 Restrictive 64
23 12 Male African 53 63 119 Restrictive 120
Table 5.5 Correlation between PM2.5 concentration and lung function outcomes
Predicted % FVC
Predicted % FEV1
Predicted % FEV1/FVC
PM2.5
concentration (µg m-3)
% Predicted FVC 1
% Predicted FEV1 0.83 1
%Predicted FEV1/FVC 0.27 0.62 1
PM 2.5 concentration (µg m-3) -0.60 -0.41 -0.18 1