It's not a good idea to have a wide array of flammable substances stored in an area that also houses the heating and cooling equipment (HVAC). Some of the containers could be open or in poor shape allowing for strong odors to build up in this small space. HVAC equipment commonly burns natural gas as the heat source which could create a major problem if combined with volatile organic compounds (VOCs). In addition, if these products are not sealed properly, the fumes from the products could be pulled into the ventilation system that is responsible for distributing fresh air through the building. These pollutants could quickly become responsible for indoor air quality issues. Play it safe! If this is the case in your building, please find a better location for the supplies.
Also, consider that children are naturally curious and much more sensitive to pollutants in the environment. You can protect children from exposure and accidental poisoning by locking up your household cleaners, pesticides, paint thinners and other chemicals in a more appropriate area. Household products can be safe and effective when stored properly. And when it is time to buy more, consider green or organic options. Now there are many green products on the market that work just as well without those harmful chemicals.
It is a simple fact of life that things get dirty and we need cleaners, solvents, powders, sprays and the like to stay on top of it all. Many of these chemicals carry warnings and cautions on how to properly store them. Large varieties of these products are petroleum based and have warnings stating that they are flammable and/or poisonous. People have come up with some strange, and even dangerous, storage places.