• Breathing
• Tobacco smoke
• Combustion sources

• Cause sleepiness and even headaches; dizziness and nausea at high levels.

• Ensure sufficient ventilation and fresh air supply

• Combustion sources, e.g. cooking stoves with open flame
• Vehicle exhaust
• Tobacco smoke

• Cause headaches, nausea, fatigue, rapid breathing, chest pain; even be fatal at high levels

• Avoid combustion in indoor environments
• Provide local exhaust when cooking
• Switch off engines when idling
• Maintain sufficient ventilation

• Combustion sources, e.g. cooking stoves with open flame
• Office equipment, e.g. photocopiers and laser printers
• Tobacco smoke

• Cause irritation to the eyes, skin and respiratory system; sometimes trigger allergic reactions

• Clean and vacuum frequently
• Avoid combustion in indoor environments
• Provide local exhaust for polluting sources
• Maintain sufficient ventilation
• Use portable air purifiers

• Combustion sources, e.g. cooking stoves with open flame
• Vehicle exhaust
• Tobacco smoke

• Cause irritation to the eyes and respiratory system

• Avoid combustion in indoor environments
• Provide local exhaust when cooking
• Switch off engines when idling
• Maintain sufficient ventilation

• Office equipment, e.g. photocopiers, laser printers and fax machines
• Air purifiers with high-voltage discharge components

• Cause irritation to the eyes and respiratory system; impair the lungs at high levels

• Isolate any ozone-emitting equipment with a local exhaust system

• Composite wood products, e.g. furniture
• Paints and adhesives
• Building materials such as urea-formaldehyde foam insulation
• Tobacco smoke
• Incense burning

• Cause irritation to the eyes and respiratory system; impair the lungs at high levels

• Select wooden furniture with low-formaldehyde emission
• Use paints and adhesives with low emission
• Air out new furniture
• Maintain sufficient ventilation
• Avoid incense burning indoors

• New furniture
• Renovation materials, e.g. paints and solvents
• Consumer and aerosol products, e.g. cleaning agents, disinfectants, pesticides, cosmetics and fragrance products
• Dry-cleaned clothes
• Tobacco smoke

• Cause irritation to the eyes, nose and throat
• Cause headaches, dizziness, and visual disorders
• Some VOCs are carcinogens

• Use no- or low-emission furniture and renovation materials
• Reduce use of VOC-containing consumer products and aerosol products
• Air out new furniture
• Maintain sufficient ventilation
• Avoid smoking indoors

• Concrete building materials containing granite

• Increases the risk of lung cancer

• Use sealant or wallpaper to cover up concrete materials
• Maintain sufficient ventilation

• Dirty filters and ducting in air-conditioners and ventilation systems
• Growth is accelerated by inadequate ventilation and damp and dusty environments

• Cause sneezing, watery eyes, coughing, shortness of breath, dizziness, lethargy, fever, and digestive problems; trigger allergic or asthmatic reactions

• Clean ventilation system and replace filters regularly
• Keep premises clean and dry (relative humidity <70%)
• Maintain good hygiene and ventilation
• Vacuum regularly

• Grow rapidly on organic matters under wet and warm conditions

• Trigger allergic reactions, e.g. headaches, sneezing, runny nose, red eyes and skin rashes

• Keep premises clean and dry (relative humidity <70%)
• Fix water leakage/seepage problems
• Clean up mould patches promptly
• Clean ventilation system and replace filters regularly
• Vacuum regularly

• Smoking

• Cause respiratory irritation and adverse effects on the cardiovascular system
• Increase the risk of lung cancer

• Avoid smoking indoors