The article lists five power tools that should not be used indoors, including drills, oscillating multi-tools, sanders, and saws, which can pose a safety risk. These tools can be safely used in both home and garage, but should only be used outdoors or in an indoor garage. Using these tools in a closed space can cause carbon monoxide poisoning or an accidental fire, and other power tools may cause damage to the interior. Wood chippers, particularly those with high-powered models, use sharp blades to transform wood into chips or fine mulch quickly and pose a potential injury risk. However, these tools can also pose a significant risk due to their high production of sawdust and high exhaust fumes. If you use a wood chipper indoors, it's difficult to filter out the sawdust faster than the wood chip creates it, leading to a major fire risk and potential for carbon monoxicosis, lung cancer, chronic obstructive lung disease (COPD), and decreased lung function. For heavy DIY renovations, concrete saws can be useful, but consider the dust created by these saws causing silicosis and lung disease, potentially leading to increased lung disease and increased breathing. Angle grinders are among the most difficult power tools for beginners due to a learning curve and potentially causing injury.