Indoor air quality. Chapter 5. At a glance. Indoor air quality 47

Chapter 5

Indoor air quality

At a glance

Household fuel-burning is a significant contributor to both ambient and indoor air pollutant concentrations. Suspended particulate concentrations were found to be orders of magnitude above recommended health limits, and concentrations of fine particulates were even higher in dwellings where wood was burned as a fuel. Ample evidence from local and international studies reveals that household fuel-burning of coal and wood can have serious adverse effects on health. Indoor air pollution from coal-burning has been established as one of the risk factors for the development of acute respiratory illnesses (ARIs). Additional sources of indoor air pollution include building materials and furnishings, deteriorated asbestos-containing insulation; wet or damp carpets; cabinetry or furniture made of specific pressed wood products; central heating and cooling systems and humidification devices; pesticides; solvents and cleaning agents, paints;

animals; moulds, dust mites, and other biological sources; and environmental (third party) tobacco smoke.

5.1 INDOOR AIR QUALITY WITHIN FUEL-BURNING HOUSEHOLDS ... 48

5.2 INDOOR POLLUTANT SOURCES (OTHER THAN FUEL-BURNING) ... 49

Indoor air quality 47

compounds found to exceed recommended health limits (Scorgie et al., 2001; Taljaard, 1998).

Ample evidence from local and international studies reveals that, when coal and wood are burned indoors other than in structured fireplaces with adequate smoke extraction, household fuel-burning can have serious adverse effects on health (Terblanche et al., 1992; Terblanche & Pols, 1994; Mathee & von Schirnding, 2003; Ehrlich and Kalkoff, 1998; Taljaard, 1998; Scorgie et al., 2001). Indoor air pollution from coal-burning has been established as one of the risk factors for the development of acute respiratory illnesses (ARI). Epidemiological data indicate that ARIs are a leading cause of death among black South African children, and their mortality rate from ARI is reported to be 270 times greater than for children in western Europe (Terblanche et al., 1993). When correlated for socio-economic status, age, and gender, the risk of upper respiratory infection (URI) in winter among rural populations exposed to coal and/or wood cooking and heating fires was found to be four times higher than the risk among electricity users (Terblanche et al., 1992).

Exposures to indoor CO concentrations were found to be up to 180% higher in coal-burning households compared to wood-burning ones within the Vaal Triangle (Terblanche et al., 1995). Data collection and exposure analysis during indoor air pollution studies (in the Qalabotjha Synthesis study [Scorgie et al., 2001]) indicated that CO (which can be lethal in high concentrations) contributed significantly to acute

5.1 INDOOR AIR QUALITY WITHIN FUEL-BURNING HOUSEHOLDS

Household fuel-burning is a significant contributor to ambient air pollutant concentrations, as well as to high concentrations indoors that have been associated with significant adverse impacts on people’s health.

Several studies have been conducted to quantify indoor air pollutant concentrations within fuel-burning households (Terblanche et al., 1993; Terblanche &

Pols, 1994; Terblanche et al., 1995; Taljaard, 1998;

van Niekerk & van Niekerk, 1999; van Niekerk &

Swanepoel, 1999). Ranges in air pollutants recorded within coal-burning households are summarized in Table 5.1. Suspended particulate concentrations were found to be orders of magnitude above recommended health limits, and concentrations of fine particulates were even higher in wood-burning dwellings. Although outdoor sulphur dioxide (SO 2 ), carbon monoxide (CO), and nitrogen dioxide (NO 2 ) concentrations within fuel- burning residential areas have not generally been found to exceed ambient air quality guidelines of the past, violations of health standards occur from indoor exposures to these pollutants ¹ .

Indoor volatile organic compound (VOC) monitoring programmes have also been undertaken. In the same way as criteria pollutants, indoor VOC concentrations varied substantially, depending on the households’

fuel-burning practices, with concentrations of various

ABBREVIATIONS: CO, carbon monoxide; NO

, nitrogen dioxide; SO

, sulphur dioxide; PM

, particulate matter less than 10 μm in diameter.

a

These air quality limits, issued by the World Health Organization (2000), were recommended for adoption in South Africa by Standards South Africa (SANS 1929:2005).

Table 5.1: Ranges of air pollutant concentrations recorded indoors within South African households during coal-burning for cooking and/or space-heating

(Terblanche et al. 1994; Taljaard, 1998; van Niekerk & van Niekerk 1999; van Niekerk & Swanepoel, 1999) Pollutant Air quality limits

Synopsis of range of indoor air pollutant

concentrations measured within households during coal burning (over 1–24-hour averaging periods) CO 30 mg/m³ for 1-hour exposure

10 mg/m³ for 8-hour exposure

25–50 mg/m³

NO

0.2 mg/m³ for 1-hour exposure 0.01–5 mg/m³ SO

0.125 mg/m³ for 24-hour exposure 1–3 mg/m³ Total particulate

matter

0.075 mg/m³ for 24-hour exposure (given by SANS 1929:2005 for PM

)

0.1–4.2 mg/m³

The burning of wood and coal indoors is of concern due to the high exposure to pollutants emitted by these fuels.

Photography: Hot Tomato Communications

and were therefore considered to pose unacceptable health risks. In assessing irritation associated with organic compounds, effects on the eyes, dermal system, and pulmonary system were taken into account. Particulate matter, rather than organic compounds, were found to be primarily responsible for irritation in the pulmonary system. Potential irritation to the eyes and dermal system were associated with exposures to organic compounds, ³ and health risks associated with the eyes and the pulmonary-cardiovascular systems occurred as a result of exposures to SO 2 .

5.2 INDOOR POLLUTANT

SOURCES (OTHER THAN FUEL- BURNING)

Many researchers who study indoor air quality believe that – even in households that do not burn fuel – overall exposure to air pollutants is greater indoors than outdoors (EPA, 1998), the reason being that there are various other sources of indoor emission and many people spend most of their time indoors (in houses, offices, schools, and shops, for example). Inadequate ventilation can raise indoor pollutant levels by not allowing the entry of outdoor air, which would dilute emissions from indoor sources, and by not allowing health risk, and that chronic health problems were a

likely consequence of particulates in the air, as well as volatile compounds such as benzene, hexane, carbon tetrachloride, and tetrachloroethylene (Taljaard, 1998).

The “Birth to Ten” research project, initiated by the Medical Research Council in 1990, aimed to assess the environmental, economic, psycho-social, and biological determinants of health, development, and well-being in a cohort of 3 275 children from birth to the age of ten years in Soweto and parts of Johannesburg (von Schirnding & Mokoetle, 1993).

The study found that 50% of children who lived in homes with an open fire experienced respiratory symptoms such as sneezing or a runny/stuffy nose, in contrast to 24% of children who lived in homes without open fires. Over half (54%) of the respondents reported that children had experienced colds and chest illness with high frequency since birth. Runny noses (53%), sneezing (38%), and a productive cough ² (28%) were among the most frequently reported symptoms of ill health. Ear infections (8%), bronchitis/bronchiolitis (5%), pneumonia (4%), and allergies (4%) were among the most frequently reported health problems diagnosed by a doctor since the birth of the child. By about the age of 14 months, 4% of the children in the study had been admitted to hospital for a chest illness.

Health risks associated with exposure to household coal-burning were quantified in the Qalabotjha Synthesis study (Scorgie et al., 2001).

The risks were calculated for each individual fuel- appliance combination considered by South Africa’s Atomic Energy Corporation (AEC) (Britton, 1998), b a s e d o n p r e d i c t e d a m b i e n t a i r p o l l u t a n t concentrations (that is, using dispersion simulations and the AEC’s 1998 emission factors as a basis).

Health risks have also been calculated for actual above-normal as well as normal coal combustion periods, based on ambient air quality data measured by the AEC during the Qalabotjha macro-scale experiment (Sowden, 1998) and indoor air quality measurements made by the CSIR during the same study (Taljaard, 1998). Cancer risks arising from bituminous coal-burning in both braziers and stoves were calculated to be greater than 1:10 000 for the haematopoietic, hepatic, and pulmonary systems,

2. A productive cough is one that produces phlegm, as opposed to a dry cough which does not.

3. ‘Organic compound’ defines material in terms of chemistry; ‘particulate’ and ‘aerosol’ defines material in terms of its physical state.

Indoor air quality 49

the pollutants to escape out of doors. Elevated temperatures and humidity levels can also increase indoor pollutant emissions.

Sources of indoor air pollution include building materials and furnishings, as diverse as deteriorated asbestos-containing insulation; wet or damp carpets;

cabinetry or furniture made of specific pressed wood products (a significant source of formaldehyde emissions); central heating and cooling systems and humidification devices; (radon gas from uranium in soil or rock on which buildings may be constructed);

pesticides; solvents and cleaning agents, paints;

animals, moulds, dust mites, and other biological sources; and environmental (third party) tobacco smoke.

Environmental tobacco smoke (ETS) – or ‘passive smoking’ – has received considerable public attention in recent years. Tobacco smoke comprises a complex mixture of over 4 000 chemical compounds, and includes respirable particles, CO, NO ₂ , nicotine, formaldehyde, ammonia, and hydrogen cyanide. Many of these are listed as toxins or carcinogens. The US Environmental Protection Agency (EPA, 1992) has classified ETS as a known human (Group A) carcinogen and estimates that it accounts for about 3 000 lung cancer deaths per year among non-smokers in the USA. Comparable statistics are unavailable for South Africa.

It is hoped that the risk of exposure to ETS in South Africa has been dramatically reduced as a result of legislation that restricted smoking in public places, confining it to purpose-designed smoking rooms with independent ventilation to the outside (Tobacco Products Control Amendment Act, [No. 12 of 1999]). A survey by the Department of Health in 1998 showed that 42% of men (over the age of 15) and 11% of woman (over the age of 15), 10% of adolescents aged 15–19 years were smokers (Department of Health, 1998). The total annual consumption of cigarettes in the country has decreased since the 1990s.

Asbestos contributes to both indoor and ambient air pollution. Asbestos mining has ceased, but exposure to airborne asbestos fibres continues, primarily by non-occupational exposure of communities using asbestos material for affordable housing, and persistent exposure in the vicinity of abandoned and unrehabilitated asbestos mine works. A study for the Department of Housing in 2001 found that asbestos materials are still widely used in affordable housing, particularly in KwaZulu-Natal, and the Eastern and Western Cape (Fridge, 2002). Problems are also associated with the use of asbestos-containing minerals for road construction. Inhalation exposure to asbestos fibres is associated with a range of pulmonary diseases, primarily asbestosis (mesothelioma-type lung cancer).

It is hoped that the risk of exposure to

environmental tobacco smoke in

South Africa has been dramatically reduced as a result

of legislation that restricted smoking in

public places

Indoor air quality 51