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Health impacts of airborne pollutants

The indoor air may contain several airborne pollutants of biological and microbiological origin that can cause health effects among people who are exposed to them. Germs may be spread among people via breathing or touching surfaces on which these pollutants settle, generally attached to dust. Humans can generate indoor bioaerosols directly. Germs are generally brought in by sick people and spread through schools via activities such as talking, sneezing and coughing. The flu virus, for example, spreads when people breathe in infected droplets that have been released into the air by coughing or sneezing (a strong sneeze can spread droplets up to 6 metres!). Coughing or sneezing into your hands can also facilitate the spread of germs if you subsequently touch smooth surfaces such as doorknobs, handles, computer keyboards or mobile phones. Washing your hands properly with mild soap and water will help to stop the spread of germs.

Typical symptoms related to bioaerosols

Other pollutants, such as allergens from plants and animals and mould spores may be present in the indoor environment and cause health effects among people suffering from allergies. Even if allergenic plants and pets are not present in the school building, pollen and fur or dander can be brought in attached to clothing.  In sensitive individuals, when indoor allergens are inhaled through the nose and into the lungs they cause allergic reactions such as itchy eyes, running nose, sneezing or skin rashes. They may also trigger breathing difficulties in people with allergic asthma. Allergic and toxic reactions may also be due to spores, cells, fragments and volatile organic compounds emitted into the indoor air from fungal and bacterial growths.

Characteristics of mould

Moulds feed on decomposing dead organic material (cellulose, lignin, dirt) and some synthetic materials such as adhesives, pastes and paints. Our indoor environments also contain food for mould such as wood products, gypsum board (drywall), wallpaper and dust. Although mould does not obtain nutrients from inorganic materials such as concrete, plastic, glass and metal, it does grow on the organic dirt or dust layer present on these surfaces. According to the WHO Guidelines for Indoor Air Quality: Dampness and Mould, the presence of many biological agents in the indoor environment is due to dampness and inadequate ventilation. The most obvious signs of a mould problem are green, brown, orange or even black spots. However, there are other, less obvious, signs, such as cracked or peeling paint, discolouration, recurrent “soot” or black streaks, bulging walls, or a musty, damp smell. Climate change is likely to influence indoor dampness and mould as a consequence of damage to school buildings from more frequent heavy rain and changes in building ventilation for hotter temperatures.

Mould-related symptoms

The colour of the mould is determined by its type and is influenced by many factors. A musty smell is an indication of microbial growth even when there is no visible mould. Indoor microbial growth and dampness have been associated with a number of respiratory problems, including:

  • Coughing and wheezing
  • Infections such as aspergillosis
  • Allergic diseases, including allergic asthma and bronchitis
  • Non-specific non-inflammatory complaints, such as eye and skin irritation, fatigue, headaches, nausea and vomiting.

The WHO guidelines therefore suggest that dampness is a strong and consistent indicator of the risk of asthma and respiratory symptoms (e.g. coughing and wheezing). Some moulds receive moisture from the air when the relative humidity is above 60 percent, or may grow when surfaces are sufficiently damp, as in the case of leaking pipes or water intrusion after heavy rain. Many researchers have pointed out how the influence of climate change and extreme weather events will facilitate mould growth, thus enhancing the risk of health effects among building occupants but also among workers and volunteers during the demolition or renovation of buildings following hurricanes, typhoons, tropical storms and flood damage.

The main teaching session will focus on encouraging hygiene measures among students and improving their awareness of the significance of dampness and mould. The children can be encouraged to follow a few simple dos and don’ts in order to improve the quality of the air in their classroom.