Expresión y motivación de la finalidad de la entrada

The noise data collection followed a consistent methodology described in chapter 5. This had already been used in other noise studies conducted by the LNEC, Division o f Acoustics.

The number o f noise samples collected indoors and outdoors were 220. Two simultaneous measurements in two contiguous rooms needed to be taken for 143 cases. Mean insulation factors were computed using the simultaneous noise measurements (indoors and outdoors) for each window type, considering the same fa9ade o f building. The mean insulation factors were used as correction factors in the Leq dB(A) SP file. This is because during the SP experiment we have told the household to consider for the other flat options presented that all characteristics not mentioned (this includes of course the same window types) were the same as in his/her present flat. The mean insulation factors for each building and window type are represented in Appendix 3. These were computed considering the average of the simultaneous noise measurements (indoors and outdoors, at each floor level) for the same exposed fa9ade (standard deviation o f the mean is less than 2dB(A)).

Considering the buildings surveyed in the vicinity of each road segment, Table 6.5 shows the range of variation of the noise levels measured indoors and at the exterior fatjade.

Table 6.5: Range of Indoor and Outdoor Noise M easurem ents, Leq dB(A) M ain road

Segment

Number o f Observations

Indoors Min , Max

Outdoors M in, Max

1.1 113 26.6, 45.7 51.7, 74.9

1.2 23 31.5, 61.5 61.5, 75.9

2.1 ¹¹¹ 23.4, 46.1 57.2, 73.2

2.2 ¹¹¹ 25.1,45.4 54.2, 72.5

3 54 21.9,49.5 58.2, 75.9

Table 6.5 shows a wide variation between the indoor and outdoor noise levels. The measures segmented by floor number are presented in Appendix 3. The WHO guidelines values for dwellings indoors are between 30 to 35 dB(A), a threshold for moderate annoyance and speech intelligibility during the daytime and evening period. Considering the noise measurements taken indoors, 243 cases (59%) had noise levels indoors of greater than 35 dB(A).

6.3 S O C IO -E C O N O M IC C H A R A C T E R IS T IC S O F T H E H O U S E H O L D A N D S E N S IT IV IT Y T O N O IS E

The sample o f households had the characteristics as follows:

Gender of the Household Representative - 257 females (62.4%) and 155 males (37.6%). The effect of gender will be tested in section 6.4, considering the number o f hours that normally a male spends home in comparison to a female. In Lisbon females tend to arrive at home much earlier in comparison to their male partners, as a result of their professions and childcare. Most SP CAPI interviews were conducted after 5:30pm, as this was the time period that most households have indicated they were at home and able to be interviewed.

Age o f the Respondent - There was no respondent on the last age category (>75), so the sample is not representative of this age group. The age group from 30 to 49 represents 56.8%

of the sampled households (Figure 6.1). The number o f respondents who refused to refer

Figure 6.1: Age group o f the household representative.

Education Level o f the Respondent - The sampled area had a high percentage o f graduate respondents (45.4%), and this fact might explain the high acceptability of the SP Noise computer survey. The number o f cases o f missing information is 40 (9.7%). The segmentation o f sample with regards to education is represented in Table 6.6.

Table 6.6: Education Levels o f the Respondent.

Education Level Number o f cases (%)

Primary School ⁸ (1.9%)

Secondary School 72(17.5% )

Technical 20 (4.9%)

Polytechnic or Bach. 32 (7.8%)

Graduate 187 (45.4%)

Posgraduate Master Level 11 (2.7%)

PhD or equivalent 3 (0.7%)

Employment status — The analysis shows that 68.5% o f the sampled households have a full­

time employment (Figure 6.2). The number of cases with missing information was 40.

Student ■

Unemployed-

Part-time Public Ad.*

Part-time Private 0?

Retired'

Housework ■

Full-Time Public Ad-

Full-time Private 0:

0.0 10.0 20.0 30.0 40.0

% of total sampled households

Figure 6.2: Em ployment status of the household representative.

Household Net Income (units: xlOOO Escudos per month, 1999 prices) - lhe distribution of households by the various income categories is represented in Figure 6.3. Group 1, the very low income less than the minimum wage salary is not represented. The number of households who did not want to state their income was 82 (19.9%).

Number of People by Household - The mean value o f the sample is 3.14 (range from 1 to 7).

Number o f People who live permanently in the flat — The mean value o f the sample is 2.99 (range from 1 to 7).

Number of children per household — The number of households without children living as a couple or alone were 183 (44.4%), 112 (27.2%) had 1 child, 82 (19.9%) had 2 children, 16 (3.9%) had 3 children and 2 (5%) had 5 children. The number o f cases with missing information was 17 (4.1%). This disaggregate information will be used to compute the adjusted household income, considering household composition

l i

]

32.3

“ i--- 1—

G roups(103 Escudos per Figure 6.3: Distribution of households by income categories.

Health status of the household (all members) - This variable was considered as an indicator

Table 6.7: Health Status of the Household.

Member

-(*) Most frequent answer was asthma and respiratory related diseases.

Awareness of the Negative Impacts of noise on health -This is also an indicator for sensitivity to noise. Householders who are aware of the negative impacts of noise on health may be more sensitive to noise in comparison to those who are not, and may have higher preferences for quiet. In the sample, 130 (31.6%) households said to be aware o f the negative

impacts of noise on health, whereas 272 (6 6%) gave negative answers. The number of observations with missing information was 10 (2.4%).

Number o f motorized vehicles per household - Only 31 (7.5%) o f the respondents said they had no car. The distribution o f cases is as follows: one car per household in 146 cases (35.4%, being 31% gasoline), 2 cars per household in 192 cases (46.6%), 3 cars per household in 30 cases (7.3%) The other 13 cases (3.1%) said to have a motorcycle and at least a car.

Number o f Years Living at the flat - Considering the length o f residence as an indicator of the experience of the respondent related to the qualitative attribute being valued (quiet indoors), it is represented in Figure 6.4 the wide variety of experiences covered. Overall, 196 households (4 7.6%) said to live in the site for a number of years equal or greater than five.

The number of cases with missing information is 6 (1.5%).

6.4 E X P O S U R E T O T R A F F IC N O IS E